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Excessive use of inorganic fertilizers disrupts soil nutrient balance and leads to soil degradation and a decrease in biodiversity. In contrast, bio-fertilizers enhance soil structure and fertility and promote plant growth and sustainable agriculture development. Therefore, this study focused on a rotation system of winter wheat and summer maize and aimed to explore the effects of applying chemical fertilizer (NPK) and bio-fertilizer (BF) in the winter wheat season on the sustainable soil development of current wheat and subsequent maize. Before sowing winter wheat four fertilization treatments were, respectively CK (100% NPK at 750 kg ha−1), A (60% NPK at 450 + 20% BF at 150 kg ha−1), B (60% NPK at 450 + 40% BF at 300 kg ha−1), and C (60% NPK at 450 + 60% BF at 450 kg ha−1), conducted. The results showed that treatment A (60% NPK + 20% BF) replacing the NPK at 300 kg ha−1 with BF at 150 kg ha−1 significantly soil nutrient contents, enzyme activity, and microbial metabolic activity. The study also found a positive correlation between soil parameters (total nitrogen, alkaline nitrogen, available phosphorus, organic matter, urease, and alkaline phosphatase in the winter wheat and maize cropping season). Furthermore, the soil microbial composition showed significant enrichment of Proteobacteria, Acidobacteria, Actinobacteria, and Firmicutes, and variations among treatments. Moreover, the application of biofertilizer enhanced the diversity of soil fungi species, particularly during the winter wheat season. This study highlights the importance of integrating biofertilizers with NPK fertilizer for agricultural system conversion and promoting agricultural production and sustainability. [ABSTRACT FROM AUTHOR]

Ever-increasing nitrogen fertilizers have posed extreme pressure on the environment for the winter wheat-summer maize rotation system in the North China Plain. Controlled-release fertilizer can be expected to serve as the nutrient-efficient and environment-friendly approach. The available nutrients are applied at controlled rates or concentration levels required for the crop growth in the soil while maintaining the nutrients for a longer period. The controlled-release fertilizers can be considered as an effective measure to improve crop yield and nitrogen use efficiency. This study aims to explore the impacts of one-time fertilization of controlled-release blended fertilizer on the crop yield, greenhouse gas emissions (GHGs) and nitrate residues in the winter wheat-summer maize rotation system. A field experiment was conducted with the summer maize cultivar of Zhengdan 958 and the winter wheat cultivar of Jimai 22. Five treatments were performed on both winter wheat and summer maize, including no nitrogen control (CK), farmers' conventional nitrogen application (FFP), optimized nitrogen application (OPT), CRU1 (the blending ratios of coated urea and traditional urea on winter wheat and summer maize were 5:5 and 3:7, respectively), and CRU2 (the blending ratios of coated urea and traditional urea on winter wheat and summer maize were 7:3 and 5:5, respectively). A comparison was then made on the yield, GHGs, and soil nitrate nitrogen residues among different treatments. The results showed that the nitrogen application significantly improved the single-season and annual crop yield in the wheat-maize rotation system (P<0.05). CRU1 and CRU2 treatments increased the summer maize, winter wheat, and annual yields by 1.4%-3.0%, 1.9%-3.4%, and 1.6%-3.1%, respectively (P>0.05), compared with FFP. Nitrogen application also significantly increased the annual emissions of soil N2O and CO2 in the wheat-maize rotation system (P<0.05). The annual accumulation of N2O emissions from soil treated with CRBF1 and CRBF2 was significantly reduced by 27.7%-34.6%, compared with FFP treatment (P<0.05). The nitrogen also increased the annual global warming potential (GWP) of the wheatmaize rotation system (P<0.05). The annual GWP of CRBF1 and CRBF2 treatments decreased by 4.2% and 5.7%, respectively, compared with FFP treatment. There was a significant difference in the CRBF2 treatment (P<0.05). The application of nitrogen reduced the annual greenhouse gas emission intensity (GHGI) of the wheat-maize rotation system. The annual GHGI of CRBF1and CRBF2 treatments decreased by 5.6% to 8.6%, respectively, compared with FFP treatments (P>0.05). CRBF1 and CRBF2 treatments were also reduced by 30.6%-34.3% (P<0.05) for the nitrate nitrogen residues in the 100-200 cm soil layer, indicating the lower risk of nitrate nitrogen leaching. In summary, the controlled-release blended fertilizer can be expected to reduce the GHGs and soil nitrate nitrogen residues for the high crop yield. The finding can provide the data and theoretical support for the highly efficient application of nitrogen fertilizer in the winter wheat-summer maize rotation system. [ABSTRACT FROM AUTHOR]

Reducing the nitrogen (N) application rate and improving water-use efficiency (WUE) are extremely important for sustainable agricultural development in wheat–maize rotation systems in the North China Plain (NCP). We conducted a three-year experiment to investigate the effects of the N application rate on the water-use characteristics of wheat–maize rotation systems in the NCP. The experiment consisted of four N application rates: 250, 167, 84, and 0 kg hm−2, denoted by N3, N2, N1, and N0, respectively. The results showed the following: For the 0–60 cm soil layer, N deficiency could lead to reduced soil water use (SWU) in wheat seasons, but in maize seasons, N deficiency showed no significant effects on SWU in the 0–60 cm layer. For the 60–140 cm soil layer, N deficiency could lead to reduced SWU in wheat seasons, but in maize seasons, the effects of N deficiency on SWU in the 60–140 cm layer varied with the SWC in the 0–60 cm layer. Throughout the three-year experiment, the evapotranspiration (ET), leaf area index (LAI), yield, and WUE of plants receiving low N treatments decreased with the growing season due to the negative effects of low N treatment (N1 and N0) on the soil. The LAI, total ET, grain yield, and WUE were all positively correlated with each other for both wheat and maize. Considering grain yield and WUE, a single-season N application rate of 167 kg hm−2 (N2 treatment) in the NCP could meet the growth needs of the wheat–maize rotation system. [ABSTRACT FROM AUTHOR]

Emissions of nitrous oxide (N2O), a potent greenhouse gas, from farmland have been recognized to be affected by soil pH and nitrogen (N) fertilizer application. However, the interactive effects of soil pH and N fertilizer type on N2O emissions and their influencing mechanism are poorly understood. A field experiment was conducted to elucidate the impacts of synthetic fertilizer and manure on soil properties and N2O fluxes along a soil acidity gradient (soil pH = 6.8, 6.1, 5.2, and 4.2) in the Huai River Basin, and a lab incubation experiment was performed to understand the underlying mechanisms of changed N2O flux. Low soil pH inhibited the ammonia-oxidizing bacteria abundance and thereby reduced the N2O production by nitrification under both synthetic fertilizer and manure application. The N2O production by denitrification was also reduced with declining soil pH, likely due to the decreased nirS and nirK abundances, and lower NO3−. However, low soil pH reduced the nosZ abundance and increased (nirS + nirK)/nosZ ratio, resulting in the increased N2O/(N2O + N2) ratio. Finally, with the decreased nitrification and denitrification, soil N2O emission was significantly reduced with declining soil pH regardless of fertilizer types. Compared with synthetic fertilizer, manure application increased soil nutrients (total N, dissolved organic C, and NO3−), nirK abundance, and (nirS + nirK)/nosZ ratio in the soils with pH of 5.2 and 4.2, thereby promoting N2O production by denitrification and N2O/(N2O + N2) product ratio in acidic soils. Consequently, soil N2O emission was increased with manure application in acidic soils. This study provides novel insight and improves our understanding of how soil pH regulates nitrification, denitrification, and N2O emissions from soils amended with chemical fertilizer and manure, which gives guidance on developing N management strategies for sustainable production and N2O mitigation in acid soils. [ABSTRACT FROM AUTHOR]

Facing the multiple objectives of increasing production, carbon sequestration, and nitrogen reduction in farmland, optimizing straw and nitrogen fertilizer management to achieve a balance between grain production and ecological safety in the wheat-maize rotation system has become increasingly critical and urgent. This study conducted a five-year field experiment in the Guanzhong Plain of China from 2017 to 2021 to investigate the effects and synergistic regulatory mechanisms of straw disposal methods (straw return, no-straw return) and nitrogen application rates (0, 150, 225, 300 kg ha−1) during the maize season on soil greenhouse gas (GHG) emissions, crop yield, and soil organic carbon (SOC) and soil toatl nitrogen (STN) content. The results showed that under the scenario of no-straw return, fertilization increased soil nitrous oxide (N 2 O) emissions by 35.9–64.0 %, and annual total crop yield by 16.4–22.8 %; however, under the straw return scenario, the increase in soil N 2 O emissions due to fertilization decreased to 26.7–62.0 %, while the yield increase rose to 19.5–25.9 %. The interaction effect between straw return and nitrogen application was significant, with straw return boosting the contribution rate of nitrogen application to yield (2.2–4.4 %) and simultaneously reducing the contribution rate of nitrogen application to N 2 O emissions (3.0–27.5 %). The study also indicated that the yield-increasing effect of straw return continued to increase with the duration of straw return, with the contribution rate to yield reaching 9.9 % after three years of continuous straw return, while the contribution rate of nitrogen application to yield increased by an average of 3.0 % per year. This suggests that there is significant potential for coupling straw return with reduced nitrogen application. Straw return combined with nitrogen fertilizer increased SOC content by 7.9–40.1 % and 3.7–12.5 %, STN content by 1.0–22.8 % and 6.1–13.9 %, respectively, compared to sole nitrogen application and sole straw return. Pathway analysis indicated that straw return combined with nitrogen fertilizer mainly enhanced soil carbon-nitrogen sequestration, improved fertilizer utilization efficiency and crop nutrition levels, reduced net global warming potential (GWP) and greenhouse gas intensity (GHGI), and synergistically regulated to increase yield while reducing GHG emissions. The study highlights that straw return lowers the threshold for nitrogen application levels, suggesting that regulating nitrogen application levels between 224 and 256 kg ha−1 during the maize season, and maintaining a nitrogen application level of 195 kg ha−1 during the wheat season, is beneficial for long-term stable production and emission reduction in the wheat-maize rotation system farmland. • Straw return enhances the contribution of nitrogen fertilization on yield. • Straw return reduces the nitrogen application's contribution to N 2 O emissions. • The positive impact of straw return on yield continued to enhance over time. • Straw return can significantly broaden the range of fertilization threshold. [ABSTRACT FROM AUTHOR]

Excessive application of synthetic fertilizer has resulted in serious soil degradation and significant greenhouse gases (GHGs) fluxes in farmlands. Partial organic substitution for synthetic fertilizer was considered as a possible strategy for sustainable agricultural development, but its potential effects on soil quality, GHGs emissions, and crop productivity remain unclear. A field experiment across 3-year was conducted to evaluate the responses of soil quality, nitrous oxide (N 2 O), carbon dioxide (CO 2), and methane (CH 4) emissions, and crop yields to different ratios of organic fertilizer (OF) to synthetic fertilizer (SF). Six treatments were included: non-fertilization (CK); total SF; total OF; 15 %, 30 %, and 45 % organic substitution (LO, MO, and HO). Soil cumulative N 2 O emission was decreased with increasing organic substitution ratios, mainly attributing to the reducing soil NH 4 + content. However, organic substitution increased soil CO 2 and CH 4 emissions due to the high manure-driven C input, consequently promoting global warming potential (GWP). Meanwhile, soil organic C, total N, P, available P, K, and C-acquisition enzyme activities were increased with organic substitution, resulting the higher soil quality index (SQI) under HO and OF. HO enhanced the annual yield of wheat and maize by 7.2 % and 13.0 % compared with SF and OF, respectively. The positive relationship between crop yield and SQI indicated that the yield-enhancing effect with partial organic substitution was mainly attributed to the improved synchronization in nutrient supply and soil fertility. Overall, partial organic substitution, especially 45 % organic substitution represents a viable strategy to improve soil quality and crop productivity while mitigating N 2 O emission in wheat-maize rotation systems. However, organic substitution promoted the GWP through stimulating soil CO 2 and CH 4 emissions. Further investigations of optimize fertilization managements are still needed to reduce manure-induced CO 2 and CH 4 emissions to achieve higher climate change mitigation. [Display omitted] • Organic substitution increased soil CO 2 and CH 4 emissions while reducing N 2 O emission. • HO and OF improved the SQI through increasing soil biochemical properties. • HO increased annual yield of wheat and maize compared with SF and OF. • Crop yield was positively related to the SQI. [ABSTRACT FROM AUTHOR]

In a wheat/maize rotation system, nitrogen (N) accounts for a large proportion of basal fertilizer, but soil N loss and the resulting environmental risk simultaneously exist worldwide. This study applied different urease/nitrification inhibitors together with basal fertilizers and investigated their effects on soil N level and grain yield. Six N stabilizing combinations consisted of two urease inhibitors (HQ and NBPT) and three nitrification inhibitors (DCD, DMPP, and Nitrapyrin). The treatments supplied with urease/nitrification inhibitors reduced, to some degree, the conversion rate of N H 4 + into N O 3 − , and kept N H 4 + content higher in surface soils for a longer time. Compared to CK, A1 treatment supplied with 1.5% HQ + 4% DCD well-maintained the levels of soil alkali-hydrolyzable N and N H 4 + . For example, alkali-hydrolyzable N and N H 4 + contents at 0–20 cm soil layer under A1 were increased by 8.59–41.6% and 8.15–14.5% more than CK, respectively. Based on the entire growth period of wheat and maize rotation, urease/nitrification inhibitors improved soil available N in surface soils but did not prevent N H 4 + and N O 3 − leaching, especially in the intensive rainfall season. The combinations of HQ and DCD or Nitrapyrin significantly enhanced crop yield. Specifically, crop yields under A1 and A3 (1.5% HQ + 0.25% Nitrapyrin) were 16.3% and 14.3% higher than CK, respectively. The N stabilizing combinations also promoted N intake and transport at every growth stage. The maximum N accumulation was increased by 27% under A1, when compared to CK. The treatments supplied with urease/nitrification inhibitors also achieved higher apparent N recovery efficiency, N agronomic efficiency, and N partial factor productivity. Consequently, the combinations of urease/nitrification inhibitors could improve N availability at 0–40 cm soil layer, which in turn improved N use efficiency of wheat and maize. The results suggested that the two urease/nitrification inhibitor combinations, 1.5% HQ + 4% DCD (A1) and 1.5% HQ + 0.25% Nitrapyrin (A3), were optimal N stabilizing agents and worthy of further study. [ABSTRACT FROM AUTHOR]

Accurate estimation of crop evapotranspiration (ET) is essential for the efficient utilization of agricultural water resources, crop production enhancement, and sustainable agricultural development. However, direct measurement of ET is highly expensive, intricate, and time-consuming, highlighting the imperative of establishing a novel model to accurately estimate ET in agricultural ecosystems. To address the above problems, this study proposed a novel model (GWA-CNN-BiLSTM), which incorporates Grey Wolf Algorithm (GWA), Convolutional Neural Network (CNN), and Bidirectional Long Short-Term Memory network (BiLSTM) as a hyperparameter adjuster, feature extractor, and regression component, respectively, to estimate ET built upon various input combinations comprising net solar radiation (R n), vapor pressure deficit (VPD), average air temperature (T a), soil water content (SWC), and leaf area index (LAI) about winter wheat-spring maize rotation system during 2012–2020 in the Loess Plateau. Besides, following a comparative assessment within GWA-CNN-BiLSTM, Convolutional Bidirectional Long Short-Term Memory network (CNN-BiLSTM), BiLSTM, Long Short-Term Memory network (LSTM), and Shuttleworth-Wallace (SW) models, the results revealed that GWA-CNN-BiLSTM under varied inputs obtained the superior performance, ranging from 0.562 to 0.957 in determination coefficient (R2), 8.4–41.5 % in relative root mean square error (RRMSE), 0.349 mm d−1 to 1.521 mm d−1 in mean absolute error (MAE), −3.26 % to 14.11 % in percent bias (PBIAS), and 0.820–1.091 in regression coefficient (b 0), respectively. Moreover, while the accuracy of BiLSTM over LSTM was evident, its performance was notably improved by the incorporation of the CNN module. Additionally, LSTM-type models under complete input combination present better precision than SW by 29.7−51.4 % in R2, 44.2−76.1 % in RRMSE, and 33.6−63.4 % in MAE, respectively. Furthermore, the accuracy of all models under varied inputs exhibited excellence in winter wheat compared to spring maize, and corresponding improvements ranged 1.4−4.3 % in R2, 5.1−20.1 % in RRMSE, and 3.1−17.9 % in MAE, respectively. Besides, the meteorological factors (R n , VPD, T a) proved to be the most important inputs for ET estimation in winter wheat and spring maize. Wherein the importance of SWC exceeded that of LAI in winter wheat, while the opposite trend was observed in spring maize. In brief, GWA-CNN-BiLSTM is the highly recommended model to estimate ET of winter wheat-spring maize rotation system under diverse input data scenarios in the Loess Plateau, which can facilitate to offer valuable assistance in regional agriculture water management decisions. • The Long Short-Term Memory (LSTM) type models surpassed Shuttleworth-Wallace. • The Grey Wolf Algorithm improved LSTM-type model performance as a hyperparameter adjuster. • ET estimation accuracy of wheat excelled over maize under the same input scenarios. • Meteorological factors were key for both crops, with soil moisture exceeding leaf area index in wheat but reversing in maize. [ABSTRACT FROM AUTHOR]

Fertilization mode affects soil quality and ecological health. The effects of four fertilization regimens on lignocellulose content, readily degradable carbohydrate decomposition, and potential microbial functions in the topsoil of a wheat--maize rotation system between 2012 and 2017 were investigated. The fertilization regimens of control (control NFNB), high chemical fertilizer (HCF), high biochar plus low chemical fertilizer (HBLCF), and biochar-based fertilizer (BBF) were compared on soil fundamental properties, microbial structure, and potential function in soil carbohydrate degradation based on metagenome analysis. The diversity of carbohydrate-active enzyme genes in the topsoil microbial consortia in the four trials was primarily distributed within the ten ecologically most dominant phyla. Application of BBF was associated with the lowest decline in total nitrogen and P2O5 (2012-2017: 6.5% and 28.1%, respectively) and the most effective carbohydrate decomposition (2015-2017: 67.0% for cellulose and 59.9% for readily degradable carbohydrate). Carbohydrate transport and metabolism accounted for 6.0% of reads assigned functional classification under the BBF regimen. These findings reveal the ecologically functional diversity of topsoil microorganisms and suggest BBF application as a promising strategy for sustainable agriculture and beneficial to soil health. [ABSTRACT FROM AUTHOR]

• Hydrus-1D model provides an alternative approach for estimating deep percolation in a flood-irrigated field. • Penman-Monteith formula is an important parameter in coupled Hydrus-1D and CROPWAT. • Hydrus-1D in combination with CROPWAT can optimum amount of water required to meet the crop water demand in the field. • CROPWAT model can improve irrigation scheduling in a flood-irrigated field under flood irrigation conditions in dry climates. Demand for irrigation water has been steadily increasing in arid regions where intensification of crop production is supported by flood-irrigation. An assessment of irrigation performance, water productivity, and irrigation schedules is critical to water conservation in dry climates. In this study, we conducted a field experiment to compare soil water balance in a flood-irrigated wheat-maize rotation system during the growing season of 2015–2016. We then modeled the soil water balance and improved irrigation strategies by coupling Hydrus-1D with the CROPWAT model, and using evapotranspiration calculated from climatic data. The calibrated Hydrus-1D model was used to simulate the temporal and spatial variation of evapotranspiration and deep percolation based on measured soil water distribution of soil profiles in the unsaturated zone. Results showed that using soil hydraulic parameters from inversion modeling can simulate soil water flow in multi-layer soil during a crop growing season. Simulation results indicated that about 36.6 and 40.6% (478.6 and 680.1 mm) of total water input in 2015 and 2016, respectively, was consumed by evapotranspiration. Furthermore, simulated deep percolation amounted for approximately 32.3 and 42.9% (403.9 and 696.6 mm) of the total amount of irrigation water in 2015 and 2016, respectively. These results indicated that only a small proportion of irrigation water was used by crops for transpiration. In addition, irrigation performance indicators such as relative water supply, relative irrigation supply, depleted fraction, and overall consumed ratio values indicated poor performance of irrigation practices in the study area. Particularly, crop yields did not increase with increases in irrigation water in flood-irrigated fields during the last ten years. Results of the CROPWAT model indicated that combinations of a fixed irrigation depth and timing, of 40 mm every 10 days, and 50 mm every 10 days were reasonable for wheat and maize, respectively, given the sandy soil in the study area. The improved irrigation strategies will limit water irrigation loss to 20% without significant effects on crop yields. This study provides an alternative approach for estimating deep percolation and crop water requirements supporting management efforts in water conservation in dry climates. [ABSTRACT FROM AUTHOR]

Graphical abstract The cumulative N 2 O emissions of CK, C1, C2, and SR treatments during the maize/wheat growing seasons of 2013–2014 (a) and 2014–2015 (b). Highlights • Low doses of biochar addition increased N 2 O emission. • High doses of biochar addition reduced N 2 O emission. • Biochar increased soil pH and the abundances of ammonia oxidizers and denitrifying genes. • Straw return increased N 2 O emission. • Application of biochar, instead of straw return, is a more optimum agricultural strategy in the wheat-maize system. Abstract To evaluate long-term effects of biochar addition and straw return (SR) on N 2 O fluxes in wheat-maize rotation system, a 2-year field experiment following a 7-year biochar addition and SR was investigated in an intensively managed agricultural soil in the North China Plain (NCP). Four treatments were included: 1) no biochar addition (CK); 2) biochar treatment with 4.5 t ha−1 yr−1 (C1); 3) biochar treatment with 9.0 t ha−1 yr−1 (C2); and 4) all the wheat/maize straw return (SR). The results showed the annual cumulative N 2 O emissions from C1 treatment were increased by 15.9–16.5%, while C2 treatment suppressed the annual cumulative N 2 O emissions by 22.8–26.3%. In comparison, straw return suppressed N 2 O emissions by 13.4–43.6% in the wheat season but increased N 2 O emissions remarkably by 45.3–53.9% in the maize season. Biochar addition enhanced the copies of AOA, AOB, nirK , nirS , and nosZ genes, while straw return decreased the copies of AOB, nirK , nirS , and nosZ genes at the high N 2 O emission period in the maize season. The production of N 2 O in the maize season was mainly driven by the AOB and nosZ genes, and by AOB gene in the wheat season. These results suggest that application of 9.0 t ha−1 yr−1 biochar is a more optimum agricultural strategy for reducing N 2 O emission in the wheat-maize system. [ABSTRACT FROM AUTHOR]

Biochar application to agricultural fields is an effective carbon sequestration measure that has the potential to reduce N 2 O emissions and increase soil water holding capacity. However, the interaction mechanisms of biochar under deficit irrigation on N 2 O emissions remain unclear. A two-year field experiment is conducted in the Guanzhong Plain, China, in order to quantify the effects of biochar and deficit irrigation on N 2 O emissions from winter wheat–summer maize crop rotation and to investigate the potential mechanisms of nitrification and denitrification. According to the combination of biochar application and actual evapotranspiration-based irrigation scheduling, four treatments are designed (B 1 W 100 : biochar 30 t·ha−1 + ET; B 1 W 80 : biochar 30 t·ha−1+ 0.8 ET; B 0 W 100 : no biochar + ET; B 0 W 80 : no biochar + 0.8ET). The soil N 2 O flux, soil physical and chemical properties, and key functional gene abundance related to N 2 O emissions in nitrification and denitrification at different growth stages are investigated and discussed. Results show that the interaction between deficit irrigation and biochar significantly reduces soil N 2 O emissions. During the wheat and maize season, the application of biochar reduces the N 2 O emissions by an average of 12.9% and 15.2%, respectively. Deficit irrigation also reduces the N 2 O emissions by an average of 17.4% and 15.5%, respectively. Pearson correlation analysis shows that soil N 2 O is significantly correlated with soil water-filled pore space during the phase with intense N 2 O emissions. Soil functional gene abundance is determined at different growth stages for both wheat and maize. Maximum soil denitrification functional gene abundance is observed at the time when wheat and maize enter the stage of their peak growth at the jointing stage. With biochar addition and deficit irrigation, the abundance of nirK and nosZ genes increases and AOB amoA genes decreases. These results suggest that biochar with deficit irrigation is a better solution to reduce N 2 O emissions from agricultural soils. • The interaction of deficit irrigation and biochar reduce N 2 O emissions from wheat-maize rotation croplands. • A sudden increase in N 2 O emissions after irrigation, with soil water-filled pore space (WFPS) as the main regulator. • Deficit irrigation and biochar addition reduced AOB gene abundance and increased nirK and nosZ gene abundance. [ABSTRACT FROM AUTHOR]

A unilateral increase in the nitrogen (N) fertilizer application depth reduces gaseous N losses in agricultural systems, however, it elevates N leaching risk. Research addressing how to better balance and optimize N emissions and leaching losses under deep placement fertilization measures remains notably limited. This study attempted to optimize the spatial distribution of N fertilizer in different soil layers to reduce total N losses and further enhance crop productivity. A two-year winter wheat-summer maize rotation experiment was conducted in the Loess Plateau during 2021–2022 and 2022–2023, and a quantitative N balance calculation framework was used to precisely estimate the variations in N losses and N surplus resulting from different single-deep fertilization (CU8, CU16, and CU24, N fertilizer was single placed in the 8, 16, and 24 cm soil layer) and layered fertilization treatments (CU2–1–1, CU1–2–1, and CU1–1–2, N fertilizer placed in the 8, 16, and 24 cm soil layer according to different proportions). The results indicated that, in comparison to the single-deep fertilization, the layered fertilization treatments increased winter wheat and summer maize yields by 4.4–21.3 % and 11.4–21.8 % (P < 0.05), N use efficiency (NUE) increased by 11.1–67.9 % and 32.3–71.0 % (P < 0.05), respectively. The single-deep fertilization struggles to meet the early growth nutrient requirements of winter wheat and summer maize (NNI < 0.95), in contrast, layered fertilization maintained optimal N nutrition status across all growth stages in wheat and maize (1.05 > NNI > 0.95); Singular increase in N fertilizer application depth reduced gaseous N losses significantly while raising N leaching risk, however, the corresponding total N losses (sum of N 2 O emissions, NH 3 volatilization, and N leaching) did not decrease; Specifically, compared with single-deep fertilization, total N loss and N surplus of layered fertilization were reduced by 15.5–37.1 % and 12.2–22.2 %, and the net economic benefits (NEB) were increased by 7.1–33.0 % (P < 0.05). Consequently, layered fertilization further optimizes the single deep fertilization measure in terms of crop production and environmental conservation, and represents an environmentally friendly and economical N fertilization practice. • Layered fertilization showed higher yield by remedy the N deficiency in single-deep fertilization. • Increasing N application depth reduced gaseous N losses and inevitably caused the N leaching. • Layered fertilization preferably balance the up-downward movement in N footprint. • N fertilizer proportion optimization in deep soil effectively reduces soil N surplus. • Layered fertilization has higher net economic benefit and is a cleaner production measure. [ABSTRACT FROM AUTHOR]

Comprehending the mechanisms underlying the response of water productivity to changing climate is essential for developing effective strategies that can maintain sustainable agricultural productivity and ecological stability amidst water scarcity and climate change. This study aimed to clarify the effects of climate and associated biologic and abiotic factors on the net water productivity (NWP) in the winter wheat—summer maize rotation system within the North China Plain (NCP), through integrating spatial-temporal pattern analysis, the Optimal Parameter-based Geographical Detector model, Random Forest, and Structural Equation Modeling. Despite climate warming and water scarcity, the NWP in the vast majority of rotation systems within the NCP exhibited an increasing trend between 2000 and 2019, which was anticipated to persist in the future. From 2000–2019, the impact of climate on the NWP exerted a fluctuating diminishment, besides the influence of WS. It is essential to add adaptive strategies that can cope with WS fluctuation in future management, to better tackle climate variability. Apart from direct effects, meteorological factors indirectly induced NWP variation primarily by influencing edaphic moisture dynamic and crop growth factors. In the paths underlying the effect of climate change on NWP, positive and negative effects coexisted. Edaphic moisture within the 40–100 cm layer played an important role in affecting NWP throughout rotation systems. To sustainably improve NWP, it was advisable to adopt deeper-rooting crop varieties in conjunction with moderate deficit irrigation and improving topsoil water retention capability. Overall, we incorporated soil and crop factors into the framework of climate impact research, providing a systematic elucidation for the mechanisms through which climate change affects NWP. Additionally, the conclusions were based on a continuous spatiotemporal framework that accounted for the geospatial heterogeneity of variables, thereby giving conclusions ample regional universality. • Soil & crop factors can help clarify mechanisms underlying climate's effect on NWP. • Despite warming and water scarcity, NWP increased and is expected to persist in future. • Impact of climate variability on NWP in wheat-maize rotation is diminishing. • Soil moisture at 40–100 cm depth is important for sustaining NWP. [ABSTRACT FROM AUTHOR]

Graphical abstract The application of controlled release fertilizer (CRF) slowed down the nitrate migration in the soil profile, and reduced the apparent N loss in the wheat-maize rotation. N accumulated below the root zone in the 40–60 cm soil layer was at a high risk of migrating deeper in the soil profile. Highlights • N accumulated below the root zone in the 40–60 cm soil layer was at a high risk of loss by leaching. • The 40–60 cm soil layer was the most sensitive one to monitor to determine NO 3 − leaching risk. • Controlled released fertilizer reduced NO 3 − in the soil, slowing its migration to the deep soil. Abstract Reducing nitrogen (N) fertilizer input into the soil is needed by a crop production and environmental pollution control. A field experiment using a wheat-maize rotation system was conducted in North China Plain (NPL) to evaluate agronomic performance and the reduction of nitrate accumulation. The trial consisted of three replicates of five treatments: no nitrogen (CK), recommended N rate (REC) (180 and 210 kg ha−1 N fertilizer as urea for wheat and maize, respectively), same amount N in the form of controlled release fertilizer (CRF), with addition of duck manure to achieve the same total N rate as REC (80% REC + DM) and conventional fertilization (CF) (315 and 270 kg ha−1 N fertilizer as urea for wheat and maize, respectively). During the continued fertilization of the rotation system, the CRF application had an equal yield, N use efficiency (48%) and residual N (175 kg ha−1) but decreased the estimated N loss (18 kg ha-1) when compared to REC (72 kg ha-1). N accumulated below the root zone in the 40–60 cm soil layer was at a high risk of migrating deeper in the soil profile. Application of CRF could effectively reduce the nitrate N accumulating in the soil, slowing down the rate of nitrate migration to the deep soil. [ABSTRACT FROM AUTHOR]

【Objective】The present study was used to determine the effects of stabilized urea on crop yield, soil nitrogen supply capacity, crop nitrogen uptake and nitrogen efficiency of wheat-maize rotation system in Central Sichuan Basin. 【Method】There were six experimental treatments including no nitrogen（ CK）, single basal application of urea( UB100 %), conventional urea treatment( UD100 %), nitrification inhibitor treated urea( DMPP100 %), reduced rate of conventional urea treatment( UD75 %) and reduced rate of nitrification inhibitor treated urea( DMPP75 %).【Result】The annual yield of total nitrification inhibitor treated urea( DMPP100 %) was 3. 99 % higher than that of conventional urea treatment( UD100 %). The annual apparent nitrogen recovery of DMPP100 %was 9. 09 percentage points higher than UD100 %, an increase of 7. 59 percentage point in wheat season and 9. 76 percentage point in maize season. The annual nitrogen uptake under DMPP100 % treatment was 20. 22 % higher than that of UD100 % treatment, 14. 34 % higher in wheat season and 23. 62 % higher in maize season. The nitrate concentration of the DMPP treated soil was lower than the urea treated soil in the prophase of crop growth. The plant nitrogen uptake was higher in plants receiving DMPP100 % than urea in the later stages of wheat and maize growth（ after florescence）. 【Conclusion】As in this case, use of the stabilized urea can produce good crop yield, and increase nitrogen acquisition of crops to enhance N fertilizer use efficiency in late growing stages. [ABSTRACT FROM AUTHOR]

Highlights • Double-blank row mulching pattern could maximize yields of wheat and maize corporately. • Soil evaporation during the two crops' seasons could be inhibited greater under double-blank row mulching pattern. • The pattern of double-blank row mulching provided alternate planting rows and fallow soils as cover. Abstract Mulching techniques have been widely used in dryland regions in northern China. It is necessary to develop water-saving cultivation techniques in irrigation regions in northern China to relieve water scarcity. Planting and mulching on separate rows has been widely used to improve wheat yield and involves a pattern of a double row of planting and a blank row of mulching. However, whether the mulching pattern during the wheat season can be applied to the wheat-maize system to increase the yield of both crops and to reduce the use of irrigation water remains unclear. Three mulching practices (conventional planting (CP), conventional planting with mulching (CPM) and double-blank planting with mulching (DPM)) during the wheat season were conducted to verify the potential roles of DPM in increasing wheat and maize yields, improving soil temperature and enhancing water storage under the DPM practice. The results show that the DPM practice significantly increased the efficiency spike number, aboveground biomass and grain yield (7.8% higher than CP and 11.3% higher than CPM) of wheat. The heat conservation effect of the DPM practice was stronger in the early stage of growth and was more effective in minimizing fluctuations in soil temperature in the wheat season compared with CPM. The development and yield of maize that was sowed in the mulching lines of DPM were less improved, although the amount of aboveground biomass at the maturity stage was higher. Additionally, the soil temperature of the maize season under DPM showed a narrowing trend of changes during the early stage with slight effects in the middle stage and a resumption of heat conservation in the late stage. Compared with CP, both mulching patterns decreased soil evaporation during the two crops' seasons by an average 5.3% in CPM and 7.8% in DPM, which is particularly evident when the crops' leaf area index was low. Therefore, the DPM pattern could more effectively optimize soil temperature and water storage. Furthermore, this pattern may have positive effects on the yields of winter wheat and on reducing the soil water requirement of the maize season. [ABSTRACT FROM AUTHOR]

Soil degradation is a common phenomenon in smallholder farmlands in Asia and Africa. To mitigate soil degradation and the subsequent elevation in agricultural productivity, it is crucial to improve soil quality using a low-cost and time-saving organic fertilization technique. Although the soil quality index (SQI) has been widely used to assess and monitor soil quality in degenerative farmlands, studies comparing SQI calculation methods are rare. The specific objectives of this study were to (1) compare the differences in SQIs calculated using principal component analysis, factor analysis, discriminant analysis, partial least squares discriminant analysis (PLS-DA), and hierarchical clustering; (2) analyze the effects of organic fertilization on soil quality in smallholdings; and (3) determine the correlations among organic fertilizer rate, soil quality, and crop yield. We analyzed 37 soil physical, chemical, and biological properties under three organic fertilization groups [high organic fertilizer group (HOF), low organic fertilizer group (LOF), and no organic fertilizer group (NOF)] as potential soil quality indicators by using multiple assessment methods in the wheat-maize rotation system in Quzhou County, North China Plain, China. SQIs calculated using PLS-DA and the nonlinear scoring method had the best discrimination ability. Compared with the NOF group, the HOF and LOF groups exhibited an increase in SQIs by 6.93–36.99% and 3.98–26.76%, respectively. The high rate of application of organic fertilizers improved soil quality and enhanced crop yield. Moreover, soil quality was positively correlated with crop yield. These results confirmed the feasibility of using organic fertilizers for soil quality improvement and implied PLS-DA to be an effective method for selecting the minimum dataset for soil quality assessment. [Display omitted] • The PLS-DA with the nonlinear scoring method is the best SQI tool. • The SQ in the HOF group is the highest among the three organic fertilization groups. • High input level of organic fertilizers increases soil quality and crop yields, simultaneously. [ABSTRACT FROM AUTHOR]

Inefficient irrigation practices have hindered crop yields, wasted irrigation water resources, and posed threats to groundwater levels and agricultural sustainability. This study evaluated different irrigation strategies for a winter wheat-summer maize rotation system to identify sustainable practices for maintaining yields while reducing groundwater depletion. A two-year field experiment was conducted, implementing three optimized irrigation strategies during the winter wheat season: I-4 (irrigated until the soil water content (SWC) of the 40 cm soil layer reaches 60% of field capacity (FC), I-6 (irrigated until the SWC of the 60 cm soil layer reaches 80% FC), and a rainfed (R) as control. Irrigation was repeated when the SWC dropped to the specified level. No irrigation level was used during the summer maize season, except for irrigation after sowing that ensuring the normal emergence of maize. WHCNS (Water Heat Carbon Nitrogen Simulator) model was developed to simulate soil water dynamics, field water consumption, and yield of both crops. The result indicated WHCNS model accurately simulated water dynamics, consumption, and grain yield. Compared to R treatment, the I-4 treatment significantly increased annual crop yield by 19.83%–28.65% (p < 0.05), while maintaining similar crop water productivity. Furthermore, the I-4 treatment achieved comparable yields to the I-6 treatment, but with a 33.91% reduction in irrigation water use, resulting in a 33.46% increase in crop water productivity and a 90.53% increase in irrigation water productivity. From a sustainable perspective, the I-4 treatment effectively reduced field water losses and maintained relatively high soil water storage, particularly in the topsoil, which was beneficial for the early growth of subsequent crops. The R treatment greatly contributed to groundwater recharge when precipitation was sufficient, while it led to severe yield losses. Overall, under the condition of annual rotation planting systems, the I-4 treatment sustainably maintained yields with less irrigation, decreasing groundwater consumption. This approach could conserve regional water resources and groundwater table while upholding agricultural productivity and achieving system sustainable water use. [Display omitted] • WHCNS model simulated soil water dynamics, field water consumption, and yield well. • I-4 reduced irrigation water by 33.91% and increased water productivity by 33.46%. • I-4 maintained topsoil moisture, beneficial for subsequent crops. • Water-saving irrigation use less groundwater, achieving sustainable agriculture. [ABSTRACT FROM AUTHOR]

Organic fertilizer can alleviate soil degradation. While numerous studies have explored the immediate impacts of organic fertilizer on soil properties and crop production, the legacy effects of organic fertilizer addition remain less understood. This research investigated the subsequent effects of organic fertilizer addition during the winter wheat season on soil microbial community structure, co-occurrence networks, soil function, and summer maize yield from 2018 to 2020. Six fertilization treatments were implemented as chemical nitrogen fertilizer (N) alone or combined sheep manure and nitrogen fertilizer (SMN) at low, medium, and high fertilization levels during the winter wheat season, with only N fertilizer applied during the maize season. The findings revealed significant variations in bacterial and fungal community structures between the SMN and N treatments. The SMN treatments increased the relative abundance of Proteobacteria, Actinobacteria, and Bacteroidetes and decreased the relative abundance of Rokubacteria, Acidobacteria, Gemmatimonadetes, Chloroflexi, and Nitrospirae compared to the N treatment. The SMN treatments had higher fungal network connectivity and lower mean path distance and modularity than the N treatment, resulting in heightened sensitivity of fungi to environmental changes. The legacy effects of organic fertilizer changed the functional potential of the N and C cycles, with keystone taxa such as Proteobacteria, Actinomycetes, Acidobacteria, Gemmatimonadetes, Bacteroides, and Ascomycota significantly correlating with functional genes related to the C and N cycles. Surprisingly, no significant differences in summer maize yield occurred between the SMN and N treatments. However, the random forest model revealed that the SMN treatments had significantly higher explanatory power of soil microbial community structure for maize yield (74.31%) than the N treatment (13.07%). These results were corroborated in subsequent studies and underscore the legacy effects of organic fertilizer addition on soil microbial communities. This research offers valuable insights into organic fertilizer use for enhancing soil quality and sustaining agricultural productivity. [Display omitted] • Stronger response of fungal networks to organic fertilizer legacy than bacteria. • Organic fertilizer legacy changed the functional potential of N cycle and C cycle. • Keystone taxa significantly correlate with genes related to the C and N cycles. • No significant difference in yield occurred between organic fertilizer legacy and N. [ABSTRACT FROM AUTHOR]

Croplands play a vital role in regional carbon budgets. We hypothesized that biophysical factors would be important for soil respiration in a wheat-maize rotation cropping system. Soil CO 2 efflux was measured using the closed chamber method, and net CO 2 exchange between the cropland and the atmosphere obtained by the eddy covariance technique in a winter wheat-summer maize double cropping system over four years (Oct 2002–Oct 2006). In addition to soil temperature, soil respiration was controlled by leaf area index and soil moisture in the wheat field and soil moisture in the maize field. Temperature sensitivity ( Q 10 ) of soil respiration was 2.2 in the wheat and maize growing seasons. In the wheat field, the Q 10 value during the sowing–returning green period (4.9) was more than that during the returning green–ripening period (2.0). On a monthly time scale, soil respiration was controlled by gross primary productivity in the wheat field, indicating that soil respiration was coupled with ecosystem photosynthesis. Annual soil respiration was 825 ± 73g C m −2 in the wheat–maize rotation system in 2003–2006. Over a 4–year average, soil respiration was 355 ± 50 g C m −2 in the wheat growing season and 470 ± 67 g C m −2 in the maize growing season, which accounted for 43% and 57% of the annual value respectively. At an annual time scale, soil respiration contributed to 72% of ecosystem respiration in the winter wheat–summer maize double cropping system. [ABSTRACT FROM AUTHOR]

Biochar amendment in soil has the potential to sequester carbon, improve soil quality and mitigate greenhouse gas (GHG) emission in agriculture, but the impact of biochar amendments on dissolved organic matter (DOM) properties of soils in the fertilized agro-ecosystem has received little research attention. This study performed a long-term field experiment to assess the influence of biochar amendments (different addition rate: 4 t ha −1 and 8 t ha −1 ) on DOM characteristics in soils in wheat-maize rotation system in Loess Plateau of China by exploiting fluorescence excitation-emission spectrophotometry and parallel factor analysis (EEM-PARAFAC). Our results showed that the content of soil DOM was significantly influenced by the addition of biochar, and the higher biochar addition markedly increased the mean concentration of dissolved organic carbon (DOC) (from 83.99 mg kg −1 to 144.27 mg kg −1 ) in soils under the same fertilizer application. Three identified fluorescent components (fulvic acid-like, humic acid-like and tryptophan-like) were found, and fluorescence intensity of those components (especially humic-like material) was enhanced with the increasing DOC in the biochar treatments but the composition of DOM was not changed. These findings would be beneficial to understand the biochar's effects and processes in decreasing GHG emissions from soils. [ABSTRACT FROM AUTHOR]

Highlights • Optimized fertilization and irrigation increase N and water utilization rate. • Lower N application and soil moisture reduce the N2O emission. • WFA and LCA method can be used to evaluate water consumption in northern China. Abstract Excessive nitrogen (N) application and shortage of water are the major obstacles to sustainable agricultural development in the high-yielding regions of the North China Plain. New cropping systems need to be created that use integrated management practices to improve the utilization of nitrogen and water and to reduce the emissions of greenhouse gases. We conducted a 4-year (2011–2015) field experiment in Huantai county using three cropping treatments: local farmers' conventional practices (FP), recommended farming management (REC), and no N fertilization (CK). The study revealed that, the mean annual grain yield of FP and REC was both 16.5 Mg ha−1 which was higher than CK (7.9 Mg ha−1). In comparison with FP, the REC treatment showed N fertilizer and groundwater input reduced by 43% and 28% with increasing of 79.3% and 61.7% of N use efficiency (NUE) and irrigation water use efficiency (IWUE), respectively. The REC treatment demonstrated consistently lower N 2 O emissions (36% on average) compared with the FP treatment. The annual net global warming potentials of the REC and CK treatments were 37% and 73% lower, respectively, than that of the FP treatment. The water footprint of the REC treatment was 30% (the Water Footprint Assessment method) to 37% (the Life Cycle Assessment method) less than that of the FP treatment. These results indicate that REC is a promising and feasible treatment for ensuring environmentally friendly, and energy-efficient sustainable agriculture in the high-yielding regions of the North China Plain. [ABSTRACT FROM AUTHOR]

Straw return plays an important role in reducing the use of chemical fertilizer, promoting soil carbon sequestration, thus maintaining soil fertility and alleviating environmental pollution. To examine the effects of straw return on soil bacterial communities, quantitative PCR and high-throughput sequencing approaches were used to analyze the bacterial abundance and community structures at the depths of 5–25 cm and 25–45 cm in the soils under six-year continuous straw return and removal treatments in Langfang, Hebei, the North China Plain. As a result, straw return had no effects on soil chemical properties, bacterial abundance, richness or diversity at both soil depths. In contrast, vertical distributions of available nitrogen and available potassium were affected. Similarly, straw return also changed the vertical distributions of Proteobacteria and Chloroflexi. Principal coordinate analysis based on weighted UniFrac distance matrix indicated a moderate separation of the bacterial community in the soil treated with straw return from that with straw removal at 5–25 cm depth, but they were not distinctly distinguished at 25–45 cm depth. T-test identified increased abundance of Candidatus Latescibacteria in the soil under straw return treatment at 5–25 cm depth but no differentially abundant phyla at 25–45 cm depth was found. These results suggested a selection effect from the six-year continuous straw return treatment and the soil bacterial communities were moderately changed. [ABSTRACT FROM AUTHOR]

Irrigation water requirement (Iwr) and soil moisture (SM) are two essential metrics that guide scientific irrigation and agricultural water-saving practices. Although they have been extensively studied in the North China Plain (NCP), an exploration into their spatial-temporal coupling pattern remains absent. Here, the spatial-temporal coupling pattern underlying the variations of Iwr and SM across the winter wheat–summer maize rotation system within the NCP was elucidated from a geographic perspective, by developing a geo-statistic framework that integrated the global spatial autocorrelation, spatial hot-spot technique, geographically weighted regression, and the optimal parameters-based geographic detector. From 2000–2019, the Iwr and SM exerted a distinct geospatial heterogeneity. Winter wheat demonstrated a spatially descending gradient in Iwr from north to south, while the pattern in summer maize Iwr varied greatly across periods. Generally, winter wheat had a higher Iwr, while the geospatial pattern of summer maize Iwr displayed a greater variability. Spatial pattern of SM in 0–100 cm soil horizon exhibited an approximately inverse trajectory to that of Iwr, while SM in 100–200 cm horizon demonstrated a spatial staggered pattern. In most cases, there existed a notable negative coupling between Iwr and SM at 0–100 cm depth, but not universal at 100–200 cm. Nonetheless, a pronounced reciprocal enhancement mechanism between SM of two layers was confirmed. Between 2000 and 2019, a geospatial decoupling trend was detected between Iwr and SM throughout the NCP. Despite remaining universality, the pattern of high irrigation demand induced by soil moisture deficit was being weakened. Given these, climate-adaptive water-saving strategies were updated, which provide a new implication for regional agricultural water-saving practice and sustainable production. • Coupling of irrigation water requirement (Iwr) and soil moisture (SM) was captured. • A geospatial decoupling trend between Iwr and SM was detected. • Interaction between SM of two soil horizons on the Iwr was confirmed. • Climate-adaptive agricultural water-saving strategies were updated. [ABSTRACT FROM AUTHOR]

Reactive nitrogen gas (Nr) originating from the soil is highly susceptible to the influence of agricultural water and fertilizer management practices, making it a critical gas that can substantially contribute to atmospheric pollution. Understanding the emission patterns of Nr in the surface soil under reclaimed water (RW) irrigation is essential for guiding RW irrigation practices and informing policies aimed at reducing Nr emissions. In this study conducted in Beijing, North China, field sites were selected with different irrigation management strategies and corresponding fertilizer application methods. The two types of irrigation water quality comprised RW irrigation and groundwater (UW) irrigation, whereas the two fertilizer types utilized were calcium ammonium nitrate with a high nitrate nitrogen content and ammonium sulfate with ammonium nitrogen. Nr emissions and concentrations in the soil profile (0–30 cm depth) were monitored throughout key agricultural events, including cultivation, irrigation, fertilization, and harvest, spanning the period from 2020 to 2021. It is observed that RW irrigation effectively reduces cumulative ammonia (NH 3) emissions compared to groundwater (UW) treatment. However, it results in increased concentrations of nitrous oxide (N 2 O) (12.33%−73.82%) and nitric oxide (NO) (13.74%−36.59%) in the soil within the depth range of 0–30 cm. Of particular importance is the notable increase in the abundance of soil denitrifying and ammonia-oxidizing archaea (AOA-amoA) genes due to RW irrigation, indicating the potential for elevated N 2 O and NO emissions. Furthermore, it is noteworthy that the soil Nr emissions and concentrations are more strongly affected by nitrogen type rather than water quality. Conversely, the inclusion of nitrate has proven to be effective in mitigating N 2 O and NO emissions in RW-irrigated farmland. • Reclaimed water irrigation increases the N 2 O and NO concentration in surface soil. • Reclaimed water irrigation can reduce soil cumulative NH 3 emissions. • Reclaimed water irrigation can lead to an increase in soil NO 2 - accumulation after fertilization. • Nitrate fertilizer has the potential to mitigate active gaseous nitrogen emissions in the soil. [ABSTRACT FROM AUTHOR]

• The IAV of NEP for wheat and maize differed in response to vegetation phenology. • Different effects of phenological metrics and abiotic factors on the IAV of NEP. • NEP max and CUP dominated the IAV of NEP for wheat and maize, respectively. • There were positive correlations between the NBP of wheat and maize and NEP. Investigating the response of net ecosystem productivity (NEP) to phenological variation for crop ecosystems is important for deeply understanding the impact of climate change on agriculture. However, its main controlling mechanisms have not been well understood for rotation cropland ecosystems. Using a 16 year (2003–2018) eddy covariance flux observation in a typical wheat-maize rotation system in the North China Plain (NCP), we explore the potential of carbon flux phenology (CFP) and abiotic factors in interpreting the interannual variability (IAV) of NEP. The results showed that the NEP of the wheat season (NEP wheat) was significantly controlled by the carbon uptake period (CUP), the end date of CUP (ECUP) and the peak value of NEP (NEP max). The increase in spring temperature reduced soil water content (SWC) in the wheat season, leading to shorter CUP, earlier ECUP and lower NEP max. However, NEP of the maize season (NEP maize) was mainly affected by CUP, the start date of CUP (SCUP) and NEP max. ECUP and CUP were negatively correlated with air temperature (T a) and soil temperature (T s) of the maize season, and NEP max had a significant negative correlation with mean summer temperature (MT su) and T a. In addition, we found that NEP max contributed the most to the IAV of NEP wheat (63%). However, CUP showed the most contributions in maize ecosystems, interpreting 30% IAV of NEP maize. When considering the export of harvested biomass, the wheat season carbon budgets were close to neutral of 21±26 g C m−2, the maize season was a carbon source of 102±18 g C m−2, and the whole year behaved as a carbon source of 129±41 g C m−2 during our study period. The study provides important insights into the response of carbon budget of cropland ecosystems to vegetation phenology shifts in the North China Plain under future climate change. [ABSTRACT FROM AUTHOR]

The nitrogen environmental endurance and optimal nitrogen input rate of wheat/maize rotation system on yellow sloping soil were studied by the field experiment with six nitrogen rates( 0,90,120,150,180,and 240 kg·hm-2) during wheat growth period and six nitrogen rates( 0,146,195,244,293 and 390 kg·hm-2) during maize growth period under high residual nitrogen in yellow sloping soil to explore high and stable yield of crops and environmental friendly nitrogen application rate in wheat / maize rotation system and reduce environmental pollution from agricultural fertilization in yellow soil area. Results: The grain yield and total nitrogen accumulation in plants show a first rising and then declining trend with increase of nitrogen rate. The yield of maize and wheat may reduce when nitrogen application rate in maize and wheat is up to 210.9 and 150.9 kg / hm2 respectively. The residual mineral nitrogen in yellow sloping soil is NO3--N mainly and its residual amount and soil nitrogen apparent surplus rate( SNASR)are significantly related with nitrogen application rate. The maize yield is 4 067.5- 4 131.9 kg / hm2 and total accumulated NO3--N in yellow sloping soil with 0-100 cm depth is 146.9-151.3 kg / hm2 when nitrogen application rate is 102.2-120.0 kg / hm2 in maize. The wheat yield is 1354.6-1395.7 kg / hm2 and total accumulated NO3--N in yellow sloping soil with 0-100 cm depth is 141.1-153.4 kg / hm2 when nitrogen application rate is 93.0-113.2 kg / hm2 in wheat. The yield of maize and wheat can reach 95.0%- 96.5% and 95.0%-97.9% of their maximum yield respectively when nitrogen application rate in maize and wheat is 102.2- 120.0 and 93.0- 113.2 kg / hm2 separately. Therefore,the suitable nitrogen application rate of wheat /maize rotation system is 102.2- 120.0 kg / hm2 in maize and 93.0- 113.2 kg / hm2 in wheat under the high residual nitrogen in yellow sloping soil considering yield,nitrogen use efficiency and environmental influence overall respectively. [ABSTRACT FROM AUTHOR]

No-tillage has become a universal management system to conserve soil water and sustain soil productivity in dryland agriculture. However, no-tillage in a long-term may produce some undesirable soil characteristics. An occasional tillage operation has been used as a mean to manage some of the defects that have emerged in NT farming systems. This study was to explore the effect of sub-soiling at different frequencies in a no-tillage farming system of an annual cropping system of winter wheat-spring maize rotation on Loess Plateau. The study consisted of three tillage practices: NT (no-tillage were applied every year), NT/ST (no-tillage were applied in first year and rotated with sub-soiling in second year), NT/NT/ST (no-tillage were applied in first two year and rotated with sub-soiling in third year). The study began in 2007 on a former spring maize field with conventional tillage and lasted for three-year rotation cycles by 2016. In ten years, for the soil physical properties, NT/ST rotation significantly decreased soil bulk density, and increased soil porosity and amount of macroaggregates (>0.25 mm) when compared to NT ( P < 0.05). For water storage, NT with ST rotations (NT/ST & NT/NT/ST) increased the soil water storage in the fallow periods. Moreover, NT/ST rotation produced higher average grain yields, WUE and economic profit in the winter wheat-spring maize cropping system when compared to NT over the ten years. However, the soil organic matter (SOM) and total N under NT with ST rotations (NT/ST & NT/NT/ST) were lower than it for NT. For this long-term experiment, NT provided a better soil nutrient condition, NT/NT/ST and NT/ST rotation showed a better effect on soil water storage in fallow. For the comprehensive productivity, NT/ST rotation showed a balanced soil properties and crop production effect among three tillage treatments. In the winter wheat-spring maize cropping system, NT/ST rotation enhanced soil physical and chemical properties and increased yield and water holding capacity of soil. We predict that the NT/ST rotation will be of great significance in promoting the development of rain-fed conservation farming in the Loess Plateau of China. [ABSTRACT FROM AUTHOR]

The North China Plain (NCP) is an intensive agricultural area and ammonia (NH 3) emission hotspot in China. Urgent mitigation actions are needed to reduce its environmental impact. A field trial was conducted, and results combined with a synthesis of existing data to assess the NH 3 loss and mitigation potentials in a wheat-maize double-crop rotation, a dominant crop production system in the NCP. Ammonia volatilization losses from N fertilizer applied to summer maize and winter wheat were 9.1% and 5.0%, respectively, based on the data synthesis, and were significantly affected by fertilizer application method and N fertilizer type. From the field trial, optimized reduction in N application rate, compared with conventional practice, had great efficiency for NH 3 mitigation. Despite their high NH 3 reduction potential, the higher input costs associated with the use of controlled-release fertilizers, replacement of urea with calcium ammonium nitrate or inclusion of double inhibitors (urease and nitrification inhibitors) with urea limited their applicability from an economic perspective. The inclusion of a urease inhibitor with urea achieved over 70% reduction in NH 3 emission and also gave a significant improvement in grain yield, net income and N use efficiency. Future adoption of NH 3 mitigation options in the NCP should focus on establishing a reduction target and consider the cost-benefits of simultaneous implementation of multiple mitigation techniques. [Display omitted] • Placement of fertilizer and fertilizer types significantly influence NH 3 emissions. • High cost of fertilizer amendment compromised economic benefits. • Using urease inhibitor showed good economic and environmental performance. [ABSTRACT FROM AUTHOR]

Straw retention (SR) and organic fertilizer (OF) application contribute to improve soil quality, but it is unclear how the soil microbial assemblage under organic amendments mediate soil biochemical metabolism pathways to perform it. This study collected soil samples from wheat field under different application of fertilizer (chemical fertilizer, as control; SR, and OF) in North China Plain, and systematically investigated the interlinkages among microbe assemblages, metabolites, and physicochemical properties. Results showed that the soil organic carbon (SOC) and permanganate oxidizable organic carbon (LOC) in soil samples followed the trend as OF > SR > control, and the activity of C-acquiring enzymes presented significantly positive correlation with SOC and LOC. In organic amendments, bacteria and fungi community were respectively dominated by deterministic and stochastic processes, while OF exerted more selective pressure on soil microbe. Compared with SR, OF had greater potential to boost the microbial community robustness through increasing the natural connectivity and stimulating fungal taxa activities in inter-kingdom microbial networks. Altogether 67 soil metabolites were significantly affected by organic amendments, most of them belonged to benzenoids (Ben), lipids and lipid-like molecules (LL), and organic acids and derivatives (OA). These metabolites were mainly derived from lipid and amino acid metabolism pathways. A list of keystone genera such as stachybotrys and phytohabitans were identified as important to soil metabolites, SOC, and C-acquiring enzyme activity. Structural equation modeling showed that soil quality properties were closely associated with LL, OA, and PP drove by microbial community assembly and keystone genera. Overall, these findings suggested that straw and organic fertilizer might drive keystone genera dominated by determinism to mediate soil lipid and amino acid metabolism for improving soil quality, which provided new insights into understanding the microbial-mediated biological process in amending soil quality. [Display omitted] • Organic fertilizer had more potential to change microbiota assembly than straw. • The microbial network robustness in OF was greater than that in SR. • The assembly of microbiota motivated keystone taxa to mediate soil metabolism. • Amending soil quality mainly by regulating soil lipids and amino acids metabolism. [ABSTRACT FROM AUTHOR]

High-input agriculture in China has successfully increased crop productivity in the past decades, but at a significant environmental cost. It is essential to improve management strategies to mitigate greenhouse gas (GHG) emissions and other environmental costs, while maintaining grain yields. However, there is a lack of studies to evaluate mitigation strategies under long-term climate variability. This paper combines field experimental data and soil–plant systems modeling to investigate the potential for improving water and nitrogen management of a wheat–maize double cropping system in North China Plain. The APSIM model was calibrated against the data and then applied to simulate crop yield and N 2 O emissions from soil in response to irrigation and nitrogen inputs. Our results show that the N fertilizer rate and irrigation amount under the local farmer practice could be reduced by 28% and 14% without sacrificing crop yield. This in turn led to a reduction in GHG emissions by 31%, mainly attributed to the decrease in emissions from the production and transportation of N fertilizer and direct N 2 O emissions from soil. Additionally, the results indicate that the direct N 2 O emissions from soil was positively correlated with N inputs, implying an increasing emission factor (N 2 O produced per unit of N input) with N application rates. It is concluded that potential exists to optimize N fertilizer rate and irrigation amount to reduce GHG emissions while still maintaining crop yield in the agro-ecosystems in North China Plain. [ABSTRACT FROM AUTHOR]

Abstract: Life cycle assessment (LCA) method was used to examine the environmental impact of wheat-maize rotation system emphasizing double high in Quzhou County. The LCA considered the entire system, from raw material extraction to grain production, in arable farming to produce 1 ton each of winter wheat and summer maize. Results indicated that double high agriculture could improve the yield of winter wheat and summer maize by 6.84% and 9.80% respectively, while decreasing the demand for non-renewable energy resources by 13.18% for winter wheat, and 17.45% for summer maize. In the double high production system, N and P fertilizer application was decreased by 5.23% and 7.79% for winter wheat production, and 2.37% and 56.54% for summer maize production. Less use of fertilizers in the winter wheat-summer maize production system decreased global warming, acidification, and aquatic eutrophication potentials. In the double high system, farmers decreased pesticide use by 10.64% for winter wheat and 19.57% for summer maize, thus reducing their potential evaporation, leaching, and surface run-off to environment. In addition, the double high agriculture decreased the heavy metal release to soil as a result of lower use of P fertilizers. In conclusion, the double high agriculture could decrease global warming, acidification, aquatic eutrophication, human toxicity, aquatic eco-toxicity, and soil eco-toxicity potentials as well as life cycle environmental impact index of winter wheat-summer maize production system. The practice in Quzhou County showed that double high system of winter wheat-summer maize production could increase food production while protecting environmental quality and conserving natural resources, and is thus applicable to North China Plain. [Copyright &y& Elsevier]

Excessive N fertilization causes the deterioration of soil microbiome. It is therefore imperative to explore the response of the microbial community in excessively N-fertilized soil to reduce subsequent N supply (RCN) and organic fertilization (OF). Hence, this study used an excessively N-fertilized plot to conduct field experiment of wheat and maize rotation over four years to assess the effects of RCN and OF on soil physicochemical and biochemical properties and bacterial diversity and community structure. RCN significantly decreased soil nitrate (NO 3 −-N) concentration, potential nitrification rate and sucrase activity, and alleviated soil acidification. OF exerted a slight influence on soil physicochemical and biochemical properties tested here. Neither RCN nor OF affected bacterial diversity, whereas RCN changed community structure by enriching beneficial taxa (relying on the ratio of RCN), such as Actinobacteria (phylum level), and Streptomyces , Kribbella , Gaiella , Gemmatimonas (genus level), etc. The concentration of NO 3 −-N was the only soil variable significantly driving bacterial community structure. The complexity and connectivity of bacterial co-occurrence network were enhanced by RCN and only slightly affected by OF. Overall, by reversing soil N enrichment, RCN had a more positive impact on bacterial community relative to OF in the over-fertilized plot. By providing an insight into soil microbial ecology, our findings suggested that moderately reducing subsequent N supply should be a prior management option for soil amendment in high-input grain production system. Nevertheless, the long-term effects of RCN and OF on soil microbiome require further investigation. [Display omitted] • Effect of RCN and OF on bacterial community in an excessively N-fertilized soil was assessed. • RCN affected bacterial community structure strongly. • RCN improved bacterial community structure by reversing soil N enrichment. • RCN enhanced complexity and connectivity of bacterial co-occurrence network. • RCN should be as a prior soil management option in high N input agroecosystem. [ABSTRACT FROM AUTHOR]

Deep-injected straw incorporation (DI-SI) is a novel soil tillage and straw management, which allowed for the formation of maize straw layer structure in the subsoil (20–38 cm) in wheat-maize rotation systems. However, little is known about how DI-SI affects soil physicochemical and enzymatic processes, as well as crop productivity. Therefore, we conducted a field experiment during 2018–2020 in the North China Plain to determine whether DI-SI would improve soil structure, nutrients, enzyme activities, and crop yield. Three treatments were included: straw removal (SR), conventional straw incorporation (SI), and DI-SI. The results showed that DI-SI improved soil structure and water retention through decreasing the bulk density and penetration resistance in 20–40 cm soil layer. DI-SI significantly increased soil organic C (67.5%), total N (61.3%), and available nutrients (i.e. NO 3 -, NH 4 +, dissolved organic C) compared with SI in the subsoil (20–40 cm), while no differences were detected among straw managements in the topsoil (0–20 cm). This was mainly attributed to the accumulation of microbial biomass C and C-, N-acquisition enzymes in the straw layers, which promoted the straw decomposition and nutrient release. Finally, with the combined effects of soil ecological processes, DI-SI significantly increased the grain yields of wheat and maize by 12.0% and 11.8% compared with SI in the second year, respectively. Our study suggested that deep placement of straw would better promote the utilization of crop residue for farming, and deep-injected straw incorporation represents a viable strategy to improve subsoil physical, chemical, and biological processes, and subsequently crop productivity in wheat-maize rotation systems. [Display omitted] • DI-SI improves soil structure and water retention through decreasing the bulk density. • DI-SI considerably increases the SOC, TN, and available nutrients in the subsoil. • DI-SI stimulates microbial and C-, N-acquisition enzymes activities in the straw layers. • Wheat and maize yields were increased under DI-SI, especially in the second year. [ABSTRACT FROM AUTHOR]

Soil microbes and nematodes are important components of soil biota that strongly affect agricultural productivity and sustainability. Currently, our knowledge on the response of soil biota to agricultural management is restricted. This study aimed to identify the relationship between microbial and nematode communities and explore the resource path that flows within the soil micro-food web under different fertilization practices in a winter-wheat/summer-maize rotation system. The experiment was a randomized complete block design with three replicates for each treatment that included unfertilized control; inorganic N, P and K fertilizer (NPK); NPK plus manure; and NPK plus maize straw. Soil samples were taken at a 0–20 cm depth when wheat and maize were harvested. The results showed that organic manure or maize straw combined with NPK fertilizers had positive effects on the soil microbial and nematode communities. For example, the incorporation of straw increased the fungal biomass. Long-term inorganic fertilization might restrain nematode biomass accumulation especially in fungivorous nematodes. The analysis of the metabolic footprints of nematodes suggested that the incorporation of straw could enhance the carbon resource flow into the soil food web by enhancing nematode biomass. Structural equation modeling analysis suggested that the bottom–up control from the microbial community to the nematode community was more obvious in the wheat season in comparison with the maize season. In addition, a relatively stronger predation relationship was found between omnivores–predators and bacterivores rather than fungivores. Our study suggests that organic management combined with NPK fertilization could effectively enhance the association between microbial and nematode communities, while a crop rotation system with maize may have a negative influence on the structure of the soil micro-food web. [ABSTRACT FROM AUTHOR]

Modelling approaches have already been used to quantitatively assess the trade-offs between crop yield and N 2 O emissions as impacted by management practices. However, the model's performance in terms of predicting N 2 O emissions was mainly assessed against total emissions per growing season or year, which may reduce accuracy in modelling due to the uncertainties in total emissions estimated using the manual (static) chamber method. Here, a comparison between optimizations for Agricultural Production Systems sIMulator (APSIM) with total N 2 O emissions and daily N 2 O emissions was conducted. We further used the validated model to develop simple surrogate models for estimating total N 2 O emissions in different years and target potential opportunities to reduce N 2 O emissions while still maintaining the grain yield under long-term climatic conditions. Five parameters relating to denitrification and nitrification were optimized using differential evolution algorithm for global optimization based on two-year field experimental data at Huantai site in North China Plain, and comprehensive simulation experiments were further conducted under long-term climate variability in an irrigated wheat–maize rotation system. The method of Levenberg-Marquardt was implemented to fit simple surrogate models for estimating total N 2 O emissions in different years, and Analysis of Variance was used for model comparison. APSIM model optimized with daily N 2 O emissions could better simulate soil N 2 O and nitrate dynamics than that optimized with total N 2 O emissions. We obtained the posterior distributions of five key parameters to which N 2 O emissions are sensitive, and demonstrated that original model using default parameters could underestimate the rate of nitrification and denitrification and the subsequent N 2 O emissions. Total N 2 O emissions increased exponentially with nitrogen application rate and mean temperature, and IPCC (1% emission factor) could underestimate whole-year N 2 O emissions when N rate was higher than the optimized nitrogen rate for crop production. We also found that there was potential to optimize nitrogen fertiliser rate to reduce N 2 O emissions while still maintaining crop yield in the irrigated wheat–maize rotation system. This study demonstrated the necessity of optimization with daily N 2 O emissions in improving model accuracy, and the posterior distributions of five parameters relating to N 2 O emissions offered reference range for future model improvement and applications. [Display omitted] • Crop yield and soil N 2 O emissions were studied using a modelling approach. • APSIM could more accurately model soil N 2 O and nitrate dynamics when five related parameters were optimized with daily N 2 O emissions. • Posterior distributions of five parameters controlling N 2 O dynamics were obtained. • Total N 2 O emissions increased exponentially with N rate and mean temperature. • N rate could be reduced by 19% without sacrificing crop yield, which in turn led to a reduction of N 2 O emissions by 34%. [ABSTRACT FROM AUTHOR]

Highlights: [•] Nitrogen loss in runoff was primarily nitrate-nitrogen. [•] In leachate, nitrogen loss was equal parts nitrate-nitrogen and ammonium-nitrogen. [•] Runoff accounted for more than two-thirds of inorganic nitrogen loss through water. [•] Using control-release nitrogen fertilizer would decrease nitrogen loss. [•] Incorporation of wheat straw to the soil would decrease nitrogen loss. [Copyright &y& Elsevier]

Excessive nitrogen (N) application results in substantial losses, as N fertilizers are wasted along with the loss of reactive N (Nr), thereby posing substantial threats to both human and ecosystem health. Nitrification inhibitors (NI) and urease inhibitors (UI) have the potential to reduce Nr loss as well as improve grain yields. However, comprehensive benefit assessments of these inhibitors from an environmental and economic perspective, including insights into the mechanisms of N fertilizer reduction, are lacking. Conducting a two-year study of a wheat-maize rotation system, urea (Ur), NI, UI, and joint inhibitors (UI + NI, UN) was established at three N rates (N1: suboptimal rate, N2: recommended rate, and N3: farmers' rate), including a N fertilizer-lacking site (N0) as a control. N fertilizer increment stimulated foreground Nr loss, and increased field Nr loss through NH 3 volatilization, N 2 O emissions, and NO 3 − leaching. There was seasonal variation in the Nr loss pathway between the maize and wheat seasons, and NO 3 − leaching only occurred during the maize season. Compared with farmers' N practice (N3Ur), N reduction and inhibitor application decreased field Nr losses by 10.9–85.2%. The efficiency of inhibitors also varied seasonally, and UI exhibited higher efficiency in the wheat season while UN in the maize season. N reduction and inhibitor application decreased the NDC by 18.4–83.1%, where N1UN and N1UI exhibited higher efficiency. Compared with N3Ur, N1Ur had a risk of yield reduction (7.6–13.9%), with N1UN and N1UI exhibiting no significant difference. The use of suitable inhibitors effectively compensated for the increase in NDC and reduction in yield under the N1 rate. Moreover, N1UN obtained the highest net economic benefits (NEB) in the maize season while N1UI in the wheat season. The combination of N1UN for maize season and N1UI for wheat season as optimizing N management, which improved the NEB by 24.7% on average compared with the farmers' N practice in the wheat-maize rotation. This optimizing N management for minimal environmental damage and maximum economic benefits could be conducive for sustainable, intensive wheat-maize cropping systems in the North China Plain. [Display omitted] [ABSTRACT FROM AUTHOR]

Drip fertigation is beneficial to improve crop grain yield (GY), water productivity (WP) and nitrogen use efficiency (NUE), but it is not clear whether drip fertigation can improve economic benefit and how much water and nitrogen should be applied for wheat-maize rotation system in semi-humid and drought-prone regions. A two-year (2018–2020) winter wheat-summer maize rotation field experiment (including twelve drip fertigation treatments (complete combination design of three irrigation (RF: rain-fed, DI: deficit irrigation, 75% ET c , and FI: full irrigation, 100% ET c) and four nitrogen levels (N0: no nitrogen, N1: 85 kg ha−1 for wheat and 90 kg ha−1 for maize, N2: 170 kg ha−1 for wheat and 150 kg ha−1 for maize) and N3: 255 kg ha−1 for wheat and 210 kg ha−1 for maize)) and a conventional practice (Con)) was conducted to explore the response of GY, NUE, WP and net income to different water and nitrogen levels in the Guanzhong Plain of China. The results showed that water and nitrogen application levels had significant effects on GY, NUE, WP and net income of winter wheat and summer maize. For winter wheat, DIN2 (the combination of irrigation and nitrogen) achieved the highest GY (9.2 t ha−1, two-year average), WP (2.11 kg m−3) and net income (11 839 CNY ha−1). For summer maize, the highest GY (11.1 t ha−1), WP (2.32 kg m−3) and net income (14 859 CNY ha−1) were observed at DIN3, RFN3 and DIN2, respectively. For winter wheat-summer maize rotation system, the highest GY (20.2 t ha−1, winter wheat + summer maize, two-year average) and net income (26 698 CNY ha−1) were observed at DIN2; and the highest WP of 2.15 kg m−3 was obtained at RFN3, but had insignificant difference with DIN2 (2.13 kg m−3) (P > 0.05). Therefore, deficit irrigation coupled with 320 kg N ha−1 (170 kg ha−1 for wheat, 150 kg ha−1 for maize) was considered as the best drip fertigation strategy for achieving high GY, WP and net income in winter wheat-summer maize rotation system. Moreover, the response surface methodology was used to determine the optimal water consumption and nitrogen application rate based on binary quadratic regression analysis. The results showed that the GY and net income can synchronously achieve 95~100% maximum values when the water consumption ranged from 434 to 496 mm and 458–500 mm, and the nitrogen application rate ranged from 165 to 211 kg ha−1 and 187–250 kg ha−1 for winter wheat and summer maize, respectively. ● Drip fertigation increased crop grain yield (GY), water productivity and net income. ● The optimal drip fertigation strategy for highest GY and net income was derived. ● Response surface methodology was used to determine optimal water and nitrogen rates. [ABSTRACT FROM AUTHOR]

Abstract: Agricultural production plays an important role in affecting atmospheric greenhouse gas concentrations. Field measurements were conducted in Quzhou County, Hebei Province in the North China Plains to quantify carbon dioxide (CO2) and nitrous oxide (N2O) emissions from a winter wheat–maize rotation field, a common cropping system across the Chinese agricultural regions. The observed flux data in conjunction with the local climate, soil and management information were utilized to test a process-based model, Denitrification–Decomposition or DNDC, for its applicability for the cropping system. The validated DNDC was then used for predicting impacts of three management alternatives (i.e., no-till, increased crop residue incorporation and reduced fertilizer application rate) on CO2 and N2O emissions from the target field. Results from the simulations indicated that (1) CO2 emissions were significantly affected by temperature, initial SOC, tillage method, and quantity and quality of the organic matter added in the soils; (2) increases in temperature, initial SOC, total fertilizer N input, and manure amendment substantially increased N2O emissions; and (3) temperature, initial SOC, tillage, and quantity and quality of the organic matter added in the soil all had significant effects on global warming. Finally, five 50-year scenarios were simulated with DNDC to predict their long-term impacts on crop yield, soil C dynamics, nitrate leaching losses, and N2O emissions. The modelled results suggested that implementation of manure amendment or crop residue incorporation instead of increased fertilizer application rates would more efficiently mitigate GHG emissions from the tested agro-ecosystem. The multi-impacts provided a sound basis for comprehensive assessments on the management alternatives. [Copyright &y& Elsevier]

This research investigated the N 2 O fluxes and community compositions of nitrifiers and denitrifiers in a winter wheat-summer maize rotation system on the North China Plain. The experiment included three treatments: 1) a control treatment (CK); 2) biochar at 10.0 t ha–1 yr−1 (C); and 3) organic fertilizer at 7.5 t ha−1 yr−1 (M). The application of biochar reduced the cumulative N 2 O emissions by 47.7% and 62.2% in the maize and wheat seasons, respectively, compared with those of the CK treatment. Organic fertilizer increased the cumulative N 2 O emissions by 311.1% in the maize season and had no significant effects on them in the wheat season. Organic fertilizer reduced the cumulative N 2 O emissions by 39.8% in the nonfertilizer period of the maize season. The cumulative N 2 O emissions in the maize season accounted for 75.2–90.0% of the annual emissions among all the treatments. Biochar and organic fertilizer affected soil N 2 O emissions mainly by changing soil denitrifiers. In the maize season, the lower abundances of Candidatus Nitrosoarchaeum (AOA- amoA), Nitrosomonas (AOB- amoA), Mesorhizobium (nirK), Magnetospirillum (nirS) and Halomonas (nirS) may result in lower N 2 O emissions in the biochar treatment, and organic fertilizer had a similar influencing mechanism on N 2 O emissions during the nonbasic fertilizer and nontopdressing periods of the maize season. In the wheat season, the dominant genus Alicycliphilus (nosZ) was the major contributor to decreasing N 2 O emissions in the biochar treatment, while there was no biomarker related to N 2 O emissions in the M treatment. The soil pH, NO 3 −-N content and water-filled pore space (WFPS) were the key factors shifting the community compositions of nitrifiers and denitrifiers in this study. The application of biochar could be a better practice to improve saline-alkali soil with lower N 2 O emissions. These findings will improve our understanding of the nitrifiers and denitrifiers response to biochar and organic fertilizer. [Display omitted] • Both biochar and organic fertilizer had potential to reduced N 2 O emissions. • The reduction of N 2 O was related to AOA, AOB, nirK / nirS and nosZ -type denitrifiers. • The two additives had similar mechanism on N 2 O in non-fertilization stage of maize. • Soil pH was the key factor affecting nitrifiers and denitrifiers communities. [ABSTRACT FROM AUTHOR]

The winter wheat-summer maize rotation system is one of the most successful intensification agricultural systems in China, but low and unstable grain yield (GY) and high soil nitrate-N leaching caused by erratic precipitation and inefficient management of irrigation and fertilization have attracted wide attention. A two-year (2018–2020) field experiment was carried out to evaluate the effects of four water and nitrogen management strategies (a conventional irrigation and fertilization (CK) and three drip fertigation treatments (rain-fed: RF, deficit irrigation: DI and full irrigation: FI)) on soil water, soil nitrate-N residual, GY, water productivity (WP), nitrogen use efficiency (NUE) and net income in a winter wheat-summer maize rotation system. The results indicated that water and nitrogen management strategies had significant effects on soil water content in the 0–320 cm soil profile. More than 90 mm soil water in the 0–320 cm soil layer was consumed by winter wheat, and the soil water consumption followed the order of RF > DI > CK > FI. The soil water consumption can be replenished by irrigation and precipitation during the summer maize season, but the soil water in 180–260 cm under RF was significantly lower than that in the other treatments, which could not be fully replenished. There was no significant difference in the nitrate-N residual in the 0–180 cm soil layer among the treatments at harvest, but the nitrate-N residual rate of CK (less than 40% and 30% at winter wheat and summer maize harvest) was significantly lower than that of drip fertigation (more than 50% and 40% at winter wheat and summer maize harvest) in the 0–60 cm soil profile, but significantly higher than that in the 60–180 cm soil profile. These results indicate that drip fertigation had a lower risk of nitrate leaching compared with CK treatment. GY and NUE of DI and FI treatments were significantly higher than those of CK and RF treatments, but DI used 25% less irrigation water than FI, resulting in higher WP. The WP of DI was increased by 6.8–7.4% and 4.2–16.0% for winter wheat and summer maize compared with FI, respectively. From the perspective of winter wheat-summer maize rotation system, the two-year average net income of DI was increased by 2.8%, 37.9% and 59.9% compared with FI, RF and CK, respectively. Therefore, deficit irrigation with nitrogen fertigation was recommended as a sustainable fertigation strategy for achieving higher grain yield, nitrogen use efficiency, water productivity and net income and reducing the risk of soil nitrate-N leaching in the winter wheat-summer maize rotation system. ● More than 90 mm soil water in 0–320 cm soil layer was consumed by winter wheat. ● The soil water of RF could not be fully replenished by precipitation. ● Drip fertigation increased the soil nitrate-N residue of 0–60 cm soil profile. ● Deficit irrigation with nitrogen fertigation achieved higher GY, WP and NUE. [ABSTRACT FROM AUTHOR]

• The compensatory effect (CE) under plastic mulching (PM) had a time window. • Crop apical meristem emergence can be the reference terminal time for the CE. • CE disappeared due to no soil temperature increases around wheat regreening stage. • For summer maize, CE did not last by the unfavorable delayed senescence under PM. • Compensatory coefficient can be calculated by inflection points of logistic equation. Plastic film mulching (PM) has a compensatory effect on crop growing degree days by increasing soil temperature. However, only few studies addressed the question whether a terminal time for the compensatory effect window exists and if it exists how it can be quantified. The objective of this study was to use the logistic equation to describe the cumulative crop plant height and to quantify the compensatory effect. Crop apical meristem emergence was used as the reference for the terminal time of the compensatory effect window. A three-year field experiment (2013–2016), conducted under continuous PM in a typical winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) rotation on the Loess Plateau, Northwest China, indicated that the logistic equation performed well in representing and quantifying the compensatory effect of PM. The compensatory effect of PM reached a plateau during winter wheat growing seasons due to the lack of increased soil temperature during regreening stage, and during summer maize growing seasons due to unfavorably delayed senescence. The terminal time can be estimated during winter wheat and summer maize growing seasons from thermal time nodes at the maximum slope (t 2) and second inflection point (t 3), respectively. The compensatory coefficients could be estimated by thermal time intervals of (0, t 1) and (t 1 , t 2)in winter wheat growing seasons and thermal time internals (0, t 1), (t 1 , t 2), and (t 2 , t 3) in summer maize growing seasons, respectively. Compensatory coefficients tended to increase with maize plant development. The minimum data requirement using a logistic equation to calculate compensatory coefficients includes data for staged plant height and mean daily air temperature. [ABSTRACT FROM AUTHOR]

Biochar application is considered an effective method of reducing nitrous oxide (N 2 O) emissions in soil. However, the mechanism and temporal effect of different doses of biochar on N 2 O emissions is still obscure. Here, we conducted a two-year field experiment to test the effects of different input amounts and frequencies of biochar on soil N 2 O emissions in North China. Biochar was applied in six different treatments in a winter wheat and summer maize rotation system: applications of 0 t/ha biochar (C0), 2.25 t/ha biochar (C1), 4.5 t/ha biochar (C2), 9 t/ha biochar (C3), and 13.5 t/ha biochar (C4) each year, and a single application of 13.5 t/ha biochar (CS) in the first year. The results showed that biochar could inhibit N 2 O emissions, reaching 20.6% to 60.1% in the wheat season and 18.1% to 39.4% in the maize season. The inhibitory effect of biochar on soil N 2 O emissions was dependent on amount and time. C3 had the best results in the wheat season, although its inhibitory effect in the maize season was not as good relative to C4 due to the lower biochar application. In addition, CS significantly reduced (27.7%) the cumulative N 2 O emissions in the first year, although the inhibitory effect disappeared in the second year. Biochar increased the nosZ gene copy numbers and promoted a reduction of N 2 O in the soil via the denitrification process. In conclusion, the inhibition of N 2 O emissions during denitrification is an important factor for reducing soil N 2 O emissions by biochar, and the inhibition of biochar is influenced by the input amount and time. Unlabelled Image • Biochar could reduce soil N 2 O emissions through regulating denitrification. • The inhibit effect of biochar on N 2 O emissions decreased with the time. • The nosZ gene and the soil NO 3 −-N were the main factors affecting N 2 O emissions. [ABSTRACT FROM AUTHOR]

Water shortage and excessive chemical fertilizers application result in low soil water and nutrient availability and limit crop production in the Loess Plateau of Northwest China. Ammoniated straw incorporation with N fertilization may be an efficient strategy to maintain agricultural sustainability. However, the interactive effects of straw incorporation and N fertilizer on the biomass water use efficiency (WUE) in the winter wheat–summer maize rotation system remain unclear. A 3-year field experiment was conducted to evaluate the effects of combining ammoniated straw incorporation and N fertilizer on soil water, biomass yield and biomass water use efficiency (WUE) in an annual summer maize (Zea mays L.)—Winter wheat (Triticum aestivum L.) rotation system. There were three treatments: (i) long straw (5 cm) mulching with N fertilizer (CK), (ii) long straw with N fertilizer plowed into the soil (LP), and (iii) ammoniated long straw with N fertilizer plowed into the soil (ALP). Compared with the CK treatment, LP and ALP led to a similar soil water storage capacity. ALP improved summer maize biomass yield and winter wheat biomass yield at the jointing-maturity stage. ALP improved summer maize WUE at the ten-leaf collar-tasseling stage and winter wheat WUE from the tillering stage to the maturity stage. Also, the ALP treatment increased the total water use efficiency (TWUE) of winter wheat by 4.1–22.0%. Overall, ammoniated straw incorporation produced the most favorable biomass yield and WUE in the summer maize—Winter wheat rotation system in the Loess Plateau of China. [ABSTRACT FROM AUTHOR]

The wheat–maize rotation system in the North China Plain (NCP) has a large amount of crop straw. However, improper crop straw management and blind fertilization lead to nutrient imbalance and accelerated nutrient loss from the soil, ultimately leading to nutrient deficiency affecting the wheat–maize rotation system. In order to explore the effects of nutrient deficiency on the yield and nutrient use efficiency of wheat and maize, the experiment was conducted in a randomized complete block design consisting of five treatments with three replicates for each treatment: (1) a potassium fertilizer deficiency and appropriate nitrogen and phosphate fertilizer treatment (NP); (2) a phosphate fertilizer deficiency and appropriate nitrogen and potassium fertilizer treatment (NK); (3) a nitrogen fertilizer deficiency and appropriate phosphate and potassium fertilizer treatment (PK); (4) an adequate nitrogen, phosphorus, and potassium fertilizer treatment (NPK); and (5) a no-fertilizer treatment (CK). The results showed that, compared with CK, the yields of wheat and maize treated with NPK were increased by 21.5% and 27.5%, respectively, and the accumulation of the dry matter of the wheat and maize was increased by 42.5% and 57.3%. In all the deficiency treatments, the NK treatment performed better in terms of yield compared to the NP and PK treatments, while the NP treatment demonstrated a greater increase in dry matter accumulation. The NPK treatment significantly improved the nitrogen use efficiency (NUE) and nitrogen harvest index (NHI) of the wheat and maize, which resulted in higher nitrogen accumulation in the NPK treatment, and the NP treatment was the best among the other nutrient deficiency treatments. The inorganic nitrogen content showed a similar trend. In conclusion, nutrient deficiency can severely restrict crop growth. Nitrogen deficiency can significantly reduce crop yields. Phosphorus deficiency had a greater impact than potassium deficiency in terms of nutrient absorption and accumulation. Therefore, nitrogen fertilizer application should be emphasized in crop rotation systems, with moderate increases in phosphorus fertilizer application. This practice can effectively improve the nutrient deficiency under the wheat and maize rotation system in the NCP and complete a rational fertilization system. [ABSTRACT FROM AUTHOR]

Straw return with chemical fertilizers is integral to improving soil quality and the sustainability of agricultural production. However, little is known about how straw return with chemical fertilizer application affects CO2 emissions and carbon pools from the perspective of nutrient stoichiometry. We conducted a 2‐year (2020–2021) field experiment in a wheat–maize rotation system in silty clay loam to study the effects of straw return and fertilizer application on CO2 emissions, soil carbon pools and yields by applying stoichiometry. A split‐plot experimental design was used (straw was main treatment, and fertilizer was the split‐plot treatment). The treatments were no straw return + no fertilizer (S0W), no straw return + mineral nitrogen fertilizer (S0N), no straw return + mineral nitrogen and phosphorus fertilizer (S0NP), straw return + no fertilizer (SW), straw return + mineral nitrogen fertilizer (SN) and straw return + mineral nitrogen and phosphorus fertilizer (SNP). The results indicated that, compared with S0W, the SNP treatment significantly increased soil organic carbon (SOC) storage by 17% and 13% in the 0–20 cm and 20–40 cm soil horizons, respectively. Additionally, compared with S0W, the SNP and SN treatments significantly increased the annual cumulative CO2 emissions by 85% and 41%, respectively. Furthermore, the SNP and SN treatments significantly increased the annual yield by 61% and 38%, respectively, compared with S0W. Our results indicated that straw and fertilizer inputs reduced the C:Nimbalance in the topsoil (0–20 cm), with fertilizer inputs showing a more pronounced effect. However, straw incorporation increased the C:Nimbalance in subsoil (20–40 cm). Redundancy analysis (RDA) and structural equation models (SEM) suggested that 0–20 cm carbon‐phosphorus ratio (C:P) and nitrogen‐phosphorus ratio (N:P) could be significant predictors of annual yield and CO2 emissions. In conclusion, straw and fertilizers enhanced soil nutrient effectiveness and reduced carbon mineralization in favour of SOC storage. However, the input of exogenous materials (straw and fertilizers) disrupted the soil ecological stoichiometric balance and stimulated microbial activity, leading to increased CO2 emissions. Overall, this study provides theoretical guidance and scientific support for the green development of agriculture. [ABSTRACT FROM AUTHOR]

The global phosphate (P) rock shortage has become a significant challenge. Furthermore, the misalignment between crops, soil, and P usage exacerbates P rock wastage in agriculture. The distinctions among various types of phosphorus fertilizers influence the phosphorus cycle, which subsequently impacts biomass, the number of grains per ear, the weight of a thousand grains, and, ultimately, the overall yield. In a four-year field experiment conducted from 2017 to 2021, we assessed the impact of various P fertilizer types on crop yield in a continuous wheat–maize rotation system. Prior to planting the crops, P fertilizers were applied as base fertilizers at a rate of 115 kg P2O5 ha−1 during the wheat season and 90 kg P2O5 ha−1 during the maize season. Additionally, nitrogen (N) was applied at rates of 120 kg ha−1 for wheat and 180 kg ha−1 for maize. The P fertilizers used included ammonium dihydrogen phosphate, ammonium polyphosphate, calcium–magnesia phosphate, ammonium phosphate, and calcium superphosphate. Urea was used as the N fertilizer with a split application—60% at planting and 40% at the jointing stage for wheat or the V12 (twelve leaf collar) stage for maize. The results showed that different P fertilizers increased the average yield of wheat and maize by 21.2–38.0% and 9.9–16.3%, respectively. It was found that ammonium polyphosphate, calcium superphosphate, and monoammonium phosphate were more suitable for application in a summer maize–winter wheat rotation system on loess soil. [ABSTRACT FROM AUTHOR]