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Background: Standing root biomass stocks are larger in the perennial grain intermediate wheatgrass (IWG; Thinopyrum intermedium [Host] Barkworth and Dewey) than annual spring wheat (Triticum aestivum L.). However, previous studies have not separated root growth from root decomposition, which presents a significant gap in our understanding of how roots can contribute to soil organic carbon (C) accrual or other soil properties through time. Methods: We used paired sequential coring and root ingrowth cores to measure standing root stock, new root production, root decomposition, and decomposed root C and N from 0 to 15 cm soil depth of 1‐year‐old IWG (IWG‐1), 2‐year‐old IWG (IWG‐2), and annual spring wheat. Results: Standing root stock was 3.2–6.5 and 6.3–9.9 times higher in IWG‐1 and IWG‐2 than wheat. Total root production was 1.7 times greater in IWG‐1 than IWG‐2. Conversely, root decomposition almost doubled from 1.39 to 2.43 kg m−3 between IWG‐1 and IWG‐2. Conclusions: In IWG, decreased root production and increased root decomposition with stand age suggest a change in growth strategy that could reduce the contribution of root‐derived C to stabilized soil C pools as IWG stands age. [ABSTRACT FROM AUTHOR]

Soil organic carbon was measured after surface application of equal C amounts from various C sources to fallow soil or a winter wheat crop for five consecutive years. Municipal biosolid produced the largest gain, followed by manure and alfalfa (Medicago sativa L.) foliage. Wheat (Triticum aestivum L.) straw, sucrose, and wood sawdust were not different than no addition. These effects were additive to and independent from the effect of fallow soil versus cropped soil. Soil cropped to winter wheat increased in C comparable to the biosolid application or to plots planted to perennial grass. Measurements 4, 6, and 12 years after a return to normal farming practices produced no change in relative or quantitative differences. These results illuminate the durability of above‐ and below‐ground contributions to soil C. Core Ideas: Increased soil organic carbon (SOC) produced by crop roots or amendments is still present 12 years later.The effect of wheat straw and sucrose on SOC was not significant, but biosolids, manure, and alfalfa increased SOC.Five years of wheat or perennial grass produced a substantial gain in SOC compared to fallow. [ABSTRACT FROM AUTHOR]

Legume inclusion into cropping systems has been proposed to maintain high crop yields while offering multiple environmental benefits. However, the effect of legumes as pre-crop on subsequent wheat yield and soil has not been well explored. Thus, a 7-year field experiment was used to determine the interactive effects of mineral fertilization and legumes (peanut, mung bean, soybean, adzuki bean) inclusion on wheat productivity and soil quality. Our results showed that legume inclusion led to a higher wheat yield advantage (52% on average) than maize–wheat rotation under no fertilization but the advantage decreased to 26% with fertilization. All legume–wheat rotation systems supported stable wheat production, where a stronger effect was observed after peanut than after maize. Meanwhile, the wheat yield under legume–wheat systems was more resistant (i.e., less variability in the yield after ceasing fertilization) and more resilient (i.e., recovering more quickly after fertilizer re-application) relative to maize-wheat. Furthermore, soil ecosystem multifunctionality increased by 0.8 times in the topsoil while maintaining soil organic carbon stocks, even with low C and N inputs under legume–wheat. Interestingly, we also observed a positive correlation between wheat yield and soil ecosystem multifunctionality. In conclusion, legume inclusion as a sustainable practice can optimize crop yields by enhancing soil multifunctionality while maintaining soil organic carbon stocks, particularly for integration into low-yielding agroecosystems. [ABSTRACT FROM AUTHOR]

High soil pH constrains the availability of many plant nutrients including phosphorus (P). Sulfur (S) application to soil is a commonly used method to reduce the soil pH in the plant root zone, increase the availability of nutrients and thus obtain a higher yield. However, the particle size of the S is the most important factor in decreasing the soil pH. This study aimed to investigate the effect of different doses of micronized S application (0, 125, 250, and 375 kg ha−1) on the chemical properties of calcareous soil and the yield and nutrient contents of two wheat cultivars (Burgos and Zhivago). The results indicated that soil pH and CaCO3 content of soil decreased with increasing doses of S application. Soil organic carbon content slightly increased with all S applications in Burgos wheat variety. The highest increase was recorded in the 375 kg ha−1 S application, but no significant difference was determined in the Zhivago variety. The available Cu content in soil varied between 3.43 and 3.55 mg kg−1, Fe content was between 13.86 and 14.93 mg kg−1, Mn content was between 22.73 and 25.65 mg kg−1, and Zn content was between 0.53 and 0.62 mg kg−1. The results revealed that soil pH and CaCO3 content decreased with liquid micronized S applications, however, the effect of S applications on exchangeable cations and heavy metal content was not significant. [ABSTRACT FROM AUTHOR]

Returning crop residue can increase soil organic matter content, and residue quality has an influence over the rate of their turnover. However, there is a lack of information concerning the biochemical transformations of organic compounds of N and C present in the crop residues during subsequent crop growth. In this study, the contents of organic N and C fractions in soils obtained using acid and alkaline hydrolysis under two crop rotations (faba bean vs. wheat rotation) were investigated. Black fallow served as a control. The mean total N increased in the order: black fallow, wheat rotation, faba bean rotation, total C and SOM were higher in the cropped soils than in black fallow. Hydrolysable-N (1-step acid hydrolysis) reached 83.7% total N, amino acid-N and threonine+serine-N were the highest in faba bean rotation and the lowest in black fallow, ammonia-N and aminosugar-N were lower in black fallow than in cropped soils. Hydrolysable-N (2-step sequential fractionation) reached 85.3% total N and significant differences were noted between the cropped soils and black fallow, with respect to both the N and C contents. 15N was mainly accumulated in the N soluble and easily hydrolysable N compounds, and these fractions were greater in cropped soils than in black fallow. N in the humic compounds increased from black fallow to faba bean rotation. A PCA analysis showed that crop rotation and soil sampling terms had a substantial influence over cluster formation. An ANOSIM test revealed significant dif­ferences between the crop rotation and term treatments. The results indicated that soil with faba bean rotation is richer in N compounds than soil with wheat as a forecrop and this may result in a reduction in N fertilizers for the succeeding crop. [ABSTRACT FROM AUTHOR]

The aim of the study was to investigate the impact of phosphorus (P) dose application effects on bread wheat (Triticum aestivum) yield, mineral nutrients concentration and soil C (C) and nitrogen (N) concentration. From 1998to date, the same soil plots (200 m2) have been fertilized regularly with the same P fertilizer doses, namely 0 (PO), 50 (P50), 100 (P100), 200 (P200) kg P2O5 ha−1 as triple superphosphate (TSP). For the current study, fertilization was done 1 week before seed planting in 2013. Wheat yield increased with increasing P dose applications under long-term field conditions. Compared to the control treatment, 50, 100 and 200 P2O5 ha−1 application significantly increased wheat yield by 60%, 85% and 138%, respectively. Agronomic efficiency decreased with P-level increases. Indigenous root infection results and number of spore count decreased due to increasing P fertilizer application. With increasing fertilizer doses, soil organic C and N increased as well. It was concluded that since plants grow better with high P doses application, it may have a positive impact on organic matter (OM) remaining in the soil and increased soil C and N concentration. [ABSTRACT FROM AUTHOR]

Purpose: The main goal of this study was to determine if ancient wheat varieties could store more carbon than modern ones in the presence or absence of inputs, due to a likely bigger and deeper root system and a slower mineralization rate. Methods: We conducted a field experiment with four modern and four ancient varieties (released before 1960 and often grown without inputs), with and without chemical inputs (nitrogen, herbicide and fungicide taken as a single factor). Root morphology was assessed by image analysis, potential catabolic activities of fructose, alanine, citric acid by MicroResp™ and overall CO2 emissions by incubating soil and roots from each modality for 60 days. Results: The breeding type did not affect root traits, substrates respiration nor CO2 emissions in our environmental conditions. The application of inputs did not affect root traits but influenced the respiration of specific substrates and CO2 emissions. The most noticeable response was due to the "breeding type x inputs" interaction: inputs increased CO2 emissions from soil and root tissues of ancient varieties by 19%, whereas no effect was observed for modern varieties. Conclusion: Taken together, our results did not support the hypothesis that ancient varieties could be more performant than modern ones in storing carbon in our experimental conditions. Increased CO2 emissions by ancient varieties in the presence of inputs showed that ancient and modern varieties differed in their phenotypic plasticity. [ABSTRACT FROM AUTHOR]

Improving soil organic carbon (SOC) has been considered as a "win-win way" for ensuring high crop productivity and mitigating chemical N input. Improving SOC can achieve higher wheat yield and simultaneously improve nitrogen (N) productivity (defined as kg grain produced per kg total N input from both indigenous and applied N). Two treatments were tested for improving SOC level. The manure treatment involved applying manure for 6 successive years, and the EM treatment involved adding peat and vermiculite once, both combined with optimized in-season N management. The performance of these two systems were compared with a traditional farming system (Control, where only straw was returned each season). N fertilizer input under all three treatments was optimized by in-season N management and was increased by 90.1% and 48.1% under EM and Manure treatments, respectively, as compared with Control. The average wheat yield for the EM and Manure treatments was 9.1 and 9.2 Mg ha–1, respectively, across all three years, which was 18.8% and 19.7% higher, respectively, than that of the Control treatment (7.7 Mg ha–1). The average chemical N application rates for the EM and Manure treatments were 139 and 146 kg ha–1, which were 24.9% and 21.1% lower than those of the Control treatment, respectively. The N productivity was 15.1% and 14.9% which was higher under Manure and EM treatments than that of the Control treatment. The high yield and N productivity were attributed to improved aboveground dry matter and N uptake by wheat, with optimal soil N supply of the root zone. The higher stem number and weight seen in individual plants with increasing SOC resulted in larger spikes and grains at harvest. Our results determined that increasing SOC combined with optimal N management achieve low chemical N input and higher grain yield by increasing productive stems and grains per spike for improving wheat individual growth. [ABSTRACT FROM AUTHOR]

Retention of crop biomass is widely recommended to improve soil organic carbon (SOC). However, the magnitude of contribution of above‐ground residues and below‐ground roots from C3 and C4 crops to SOC is unclear.Data from a 10‐year field experiment and a 60‐day laboratory incubation were synthesized to identify the respective contribution of C3 (e.g., wheat) and C4 (e.g., maize) residues and roots to SOC, as well as its underlying mechanisms under no‐till (NT) using 13C labelling trace in wheat‐maize rotations.The field experiment showed that residue retention significantly increased SOC accumulation, and SOC derived from wheat was 126.0% higher than that from maize. Conversion to NT promoted SOC derived from wheat and thus accumulated 17.6% higher SOC stock compared with plough tillage (PT) under residue returning at 0–20 cm soil depth (p < 0.05). The data from laboratory incubation revealed the mechanisms that lower priming effects at 0–10 cm depth decreased total mineralization by 91.8% after inputs of wheat residues and roots compared with that of maize residues and roots, especially under NT compared with PT. Priming effects were negatively correlated with enzyme activities associated with the C recycle, SOC, and total nitrogen (TN) contents (p < 0.01). NT increased enzyme activities, SOC, and TN contents and thus reduced priming effects and improved residual carbon.Synthesis and applications. These results suggested that wheat may contribute more to SOC accumulation than maize, and carbon increment efficiency in farmland could be enhanced by considering the crucial roles of C3 crops in SOC accumulation. NT practice sustains the benefits of C3 crops to SOC sequestration in the upper soil depths. [ABSTRACT FROM AUTHOR]

Soils with high organic carbon (SOC) have been shown to enhance crop yields while minimizing climate-induced losses. However, the resilience impacts and mechanisms by which high SOC enhances crop performance have not been fully explored. Here, eight-year rotations of winter wheat and summer maize managed with chemical fertilizer input alone (CF) or with cattle manure (OM) or with peat and vermiculite (PV) were conducted, and various soil properties were measured alongside crop growth, nitrogen (N) uptake, and grain yield, with seasons categorized as dry or normal based on precipitation amounts. The OM and PV treatments increased SOC by 57% and 78% relative to the CF, respectively, and improved soil nutrient availability and the soil quality index. Soil moisture content in the 0–30 cm layer increased by 3.5–26.6%, but was less influenced in the 30–90 cm soil layers. Annual yield of wheat plus maize increased by 13% and 12% in OM and PV compared to the CF, and the yield sustainability index increased by 29% and 17%. Yield gains were more pronounced in dry compared to normal seasons, ranging from 19% to 28% and 12–15% for wheat. At least in part, the relative advantages of OM and PV treatments under drying conditions were associated with accelerated growth and N uptake rate from sowing to stem elongation for wheat and maize. Among the factors influencing yield in the present study, soil moisture exerted the greatest positive total effect on yield. Overall, the results highlight that enhanced SOC resulting from combined application of organic amendments and mineral fertilizer was positively associated with yield by promoting soil quality and water availability, with a more pronounced benefit under water-limited conditions. [Display omitted] • Improved soil quality and moisture enhance wheat and maize yield and stability. • Combined inorganic fertilizer and organic amendments increased soil moisture in the 0–30 cm but not in deeper layers. • Better soils with high SOC enhanced wheat and maize yield and stability during dry seasons. • Accelerated vegetative growth and nutrient uptake by high SOC contributed to productivity resilience. [ABSTRACT FROM AUTHOR]

Straw return is an effective measure to promote sustainable agriculture by significantly improving soil fertility. At present, few studies have been conducted on the most effective carbon enhancing management measures for various crops. Therefore, we conducted a meta-analysis using data collected from 184 literature sources, comprising 3297 data sets to analyze the carbon increase effects of straw returning in three main crops (rice, maize, and wheat) in China and to explore the influence mechanism of natural factors, soil properties, straw return measures, and cropping systems on the carbon enhancement effect. The study showed that straw return significantly increased soil organic carbon and the rate of increase was higher for wheat at 15.88% (14.74%–17.03%) than for rice at 12.7% (11.5%–13.91%) and maize at 12.42% (11.42%–13.42%), with varying degrees of improvement in other soil physicochemical properties. Natural factors have the greatest impact on the carbon increasing effect of rice fields, reaching 28.8%, especially at temperature between 10 °C and 15 °C, less than 800 mm precipitation, low latitude, and short frost-free period. Maize and wheat are most affected by soil properties, reaching 41% and 34.5% respectively. Furthermore, field management practices also play a pivotal role, organic carbon increasing obviously was observed when the C/N ratio of exogenous nutrients is bigger than 20 with the low initial organic matter. Shallow tillage and less than 7.5 t hm−2 straw returning with 3–10 years to the field are ideal for rice and maize. Crop rotation, especially in drylands, increased soil organic carbon more significantly than continuous. The results of our analysis can provide valuable insights into the effect of straw return on carbon increase. In the future, the soil carbon can be improved by adopting rational cropping patterns and straw return measures with taking into account climate and soil characteristics for different crops. [Display omitted] • The effects of straw return on soil organic carbon in three major crops were studied using meta-analysis. • SOC levels significantly increased for rice, maize, and wheat after straw return. • The impact of natural factors, soil properties, straw return measures, and cropping systems varied for different crops. • The increase in SOC for rice was largely influenced by natural factors, while for maize and wheat by soil properties. [ABSTRACT FROM AUTHOR]

Post-harvest crop residues are the main carbon source for arable lands. The aim of this research was to determine the amount and portion in the phytomass of post-harvest crop residues of major crops and carbon, which is input to soil with them. For this purpose, samples of winter and spring wheat, barley, oats, and soybean were taken in five farms of Kursk, Ryazan, and Samara oblasts and in the Chuvash Republic in 2019–2021. The ratio between plant fractions—roots, stubble, stems, leaves, chaff, and grain—was calculated. Post-harvest residues (roots and stubble) of cereal and leguminous crops account for 1/4–1/5 of the dry phytomass: the stubble portion is 1/6–1/10 of the mass and the share of roots does not exceed 10%. The portion of productive part (grains and chaff) is 1/2–1/3, and that of by-products (stems and leaves) is 1/3 for cereals and 1/2 for soybean. The amount of carbon input to the plow layer with root residues decreases in the sequence: winter wheat (569 kg C/ha) > spring wheat (508 kg C/ha) > barley (503 kg C/ha) > oats (488 kg C/ha) > soybean (204 kg C/ha). The stubble of field crops is an additional carbon source for the soil, the amount of which is directly proportional to the plant height: 419 kg C/ha for spring wheat, 405 kg C/ha for winter wheat, 281 kg C/ha for oats, 232 kg C/ha for soybean, and 135 kg C/ha for barley. Regression equations of the dependence of the amount of stubble and root residues on grain yield were calculated for winter wheat. [ABSTRACT FROM AUTHOR]

In the context of climate change, soil is a major pool of stable carbon on earth, yet knowledge on soil carbon turnover is limited. The difference in 13C/12C content observed between C3 and C4 plant crops has been widely used to distinguish the sources of soil organic carbon under continuous monoculture, but not in C3–C4 rotations. We studied the stability of the δ13CSOC content and the effect of no tillage, conventional tillage, and rotary tillage in 4 soils sampled at 0–5, 5–10, and 10–20 cm depth, in 2018–2019 in a field with long-term history of wheat (C3) and maize (C4) rotations. We also analyzed the results from the literature. The results show that the δ13CSOC is not statistically affected by the sampling date, thus allowing to use this method to distinguish C3 and C4 plant contributions in rotations. Moreover, no-tillage favored the preservation of wheat carbon, and this preservation was accentuated at 10–20 cm depth. δ13CSOC is also affected by fertilization and irrigation. The literature confirmed that wheat-derived carbon is better preserved that maize-derived carbon, on the average. [ABSTRACT FROM AUTHOR]

Policy and market incentives are rapidly expanding to promote soil organic carbon (SOC) sequestration in global croplands. Evidence suggests that long-term increases in SOC can influence both crop yield and nitrogen (N) fertilizer requirements, with the potential to help address two important sustainability challenges. However, increases in SOC may also trigger higher soil nitrous oxide (N 2 O) emissions, which would represent an important tradeoff for climate change mitigation. We tested the hypothesis that long-term increases in SOC are associated with higher crop yields and fertilizer N use efficiency (NUE), but at the cost of higher N 2 O emissions. Wheat was grown in two soils (SOC low and SOC high) under three N fertilizer rates (0, 100, and 200 kg N ha−1) in a mesocosm experiment. Soils were obtained (0–25 cm) from a 22-yr field experiment on no-till and cover cropping in California. Results indicate that total biomass and grain yield were higher for SOC low than SOC high at 100 kg N ha−1 but not the other N levels. Crop N uptake was also 28% greater for SOC low at 200 kg N ha−1, resulting in higher overall NUE. Soil N 2 O emissions increased for SOC high by 25–112% compared to SOC low , likely due to long-term changes in labile C and N pools, microbial activity, and soil structure influencing porosity and gas diffusion. While there are well-documented crop and environmental benefits from enhancing SOC in agricultural soils, results from this study suggest that changes in soil N 2 O emissions should be considered to accurately determine net GHG emission reductions. • Soil N 2 O emissions increased 25–112% with long-term soil carbon sequestration • Crop yields were not higher with increased SOC • Crop nitrogen uptake and nitrogen use efficiency decreased with increased SOC • Elevated N 2 O emissions presented a tradeoff for net GHG emission reductions [ABSTRACT FROM AUTHOR]

There is increasing interest in perennial crops to build soil carbon (C), but the mechanisms underlying soil C accrual in perennial croplands remain unclear, especially over time in the first years of perennial crop growth. To address this gap, research is needed that directly tracks intra-annual C fluxes through crop-microbial-soil pools, evaluating the capacity of perennial crops to build soil C over intra-decadal time periods. We conducted a 13C isotope-tracer study to compare within-season C uptake and crop-microbial-soil C partitioning patterns between 1-year-old (IWG-1) and 2-year-old (IWG-2) stands of a novel perennial grain crop, intermediate wheatgrass (IWG; Thinopyrum intermedium (Host) Barkworth and Dewey). We compared these to a common annual grain crop, spring wheat (Triticum aestivum L.). Crop shoots, roots, soil, and soil respired-C were sampled ten times over a 90-day chase period. We also measured the incorporation of recently assimilated 13C into soil microbial biomass (13C PLFA) and functional groups over the first 7 days post-label application. Overall, IWG-1 assimilated almost 1670 mg 13C m−2 during the study period, nearly twice that of IWG-2 or wheat, but neither IWG system retained significant amounts of new C in soil. Rather, a higher proportion of assimilated new C was retained in IWG-1 in root tissues (14%) and arbuscular mycorrhizal fungi when compared to other cropping systems, while IWG-2 retained almost 50% of total assimilated C in aboveground crop tissues. We expect the shift from new C retention in belowground root-mycorrhizal networks to aboveground tissues is associated with a shift from an acquisitive to conservative growth strategy that occurs between the first and second IWG production years. The observed shift in C partitioning patterns and potential change in growth strategy limited the allocation and retention of new C in soil as IWG aged, adding valuable context to our understanding of why perennial grain crop establishment seldom leads to significant carbon gains in the first several years following establishment. • 13C-CO 2 labelling revealed age-related changes in perennial grain C partitioning • 1st-year perennial grain retained new C in roots, but little new C retained in soil • Sharp decline in new C uptake and belowground retention in 2nd-year perennial grain • Changes in primary microbial consumers of new C observed between 1st- and 2nd-year [ABSTRACT FROM AUTHOR]

Wheat plays a crucial role in Morocco's food security, economic stability, and livelihoods of farming communities. Assessing key vegetation indices (as yield predictors), along with understanding potential yield, yield gap, and major determinants for this gap at regional and national scales, is vital for improving food security with resilience in variable climatic conditions. Analysing the yield gap and its causes during drought and optimal weather conditions can reduce crop failure risks and enhance productivity specially in variable rainfed production systems. This study aimed to develop scalable methodology to predict field- and landscape-level yield and yield gaps for wheat and their underlying causes examplifying Morocco's rainfed production environment combining remote sensing, machine learning, and ground information. By analysing six vegetation indices (EVI2, CGVI, MSR, NDVI, OSAVI, and RVI) derived from Sentinel-2 satellite imagery (10 m resolution) over three successive growing seasons (2018–2019, 2019–2020, and 2020–2021), the study employed advanced vegetation index models for accurate prediction of wheat yields and yield gaps at plot and on a larger regional scale within the Rabat-Sale-Kenitra region. To identify the determinants of yield gap, climate and soil datasets were merged with crop management information and the random forest model was fine-tuned and assessed for each season and cumulatively. The findings highlighted that RVI, GCVI, and NDVI vegetation indices were particularly effective in predicting wheat yields, showing the highest R2 and the lowest prediction errors (RMSE). Such predictive methodologies are crucial for policymakers to proactively plan and mitigate risk minimization and adaption plans at regional and national levels. The models predicted rainfed potential yields of 5.99, 1.53, and 4.66 t ha−1, with corresponding yield gap of 3.38, 0.73, and 1.58 t ha−1 for the seasons of 2018/2019 (favorable); 2019/2020 (drought) and 2020/2021 (favorable), respectively. Across three periods, critical factors determining yield include soil moisture, total rainfall during the crop growing period, evapotranspiration, and soil texture and carbon content. To minimize drought risks and maximize benefits during variable rainfall conditions, it is essential to implement pre-season drought forecasts, customize seeding dates based on soil moisture, adopt technologies that enhance soil moisture retention, and utilize climate-adapted farming practices in the semi-arid and arid rainfed regions. • Predicting yield gap and determinants is essential for improving resilience. • RVI, GCVI, NDVI, OSAVI, and EVI2 are top indicators for wheat yield prediction. • Yield gap of wheat varies from 1.53 to 5.99 t ha−1 in rainfed areas. • Soil moisture, rainfall and crop management are yield determinants in rainfed area. • Drought forecasting and tailored agronomy based on soil moisture are imperative. [ABSTRACT FROM AUTHOR]

Combining ability effects for yield related traits can serve as selection criteria to pursue breeding for optimal biomass allocation in wheat (Triticum aestivum). The objective of this paper is to provide information based on a retrospective quantitative genetic analysis on combining ability studies of wheat for yield and yield‐related traits to predict potential genetic gains achievable in improving biomass allocation for drought tolerance and soil carbon storage. The study compares data on the general combining ability and specific combining ability effects of wheat for yield and related traits under optimum and drought stressed conditions from 40 studies around the world. Days to heading (DTH), plant height (PH), number of tillers per plant (TN), kernels per spike (KPS), 1,000‐kernel weight (TKW), shoot biomass (SB), and grain yield (GY) exhibited wide variation for general combining ability (GCA) and specific combining ability effects. Progeny performance increased by 14.30 and 4.04% for SB and GY, respectively, compared with parental values under optimum water conditions. Number of tillers and SB exhibited positive associations with GY (.45 ≤ r ≤.85, p <.05) under both water conditions. Meta effect sizes for drought stress were negative. The highest meta‐effect sizes were calculated for DTH (−4.5) followed by SB (−2.0), whereas KPS (−1.25) had the lowest. The genetic gains for PH, SB, and other yield components showed that divergent crosses involving complementary parents could enhance biomass allocation patterns in wheat. This could be used as a basis for improving biomass allocation to roots. Core Ideas: There is sufficient genetic variation in wheat genotypes for manipulating biomass allocation.The number of kernels per spike is stable under varying moisture conditions.Shoot biomass and grain yield expression are severely confounded by drought.Aboveground traits are important for indirect selection of root traits. [ABSTRACT FROM AUTHOR]

The effect of conservation tillage on soil organic carbon (SOC) sequestration and crop production is controversial in semi‐arid areas. In addition, fertilisation is another essential factor affecting soil carbon pool and crop yields. We sought to explore the changes of SOC pool and crop productivity after optimising fertilisation and tillage. An 11‐year field experiment on the Loess Plateau in China was conducted to evaluate the effects of (i) fertilisation (balanced fertilisation, low fertilisation, conventional fertilisation) and (ii) tillage (no‐tillage, subsoiling, ploughing) on input‐C, SOC stocks, labile C fractions, C pool management index (CMI) and wheat yield. SOC stock accumulation at 0–35 cm depth under balanced fertilisation increased by 59% compared to conventional fertilisation due to the larger amount and stabilisation efficiency of input‐C. Simultaneously, balanced fertilisation increased labile C contents and CMI at 0–10 cm depth. For tillage, no‐tillage and subsoiling improved input‐C and its stabilisation efficiency, and increased SOC stocks compared to ploughing. Balanced fertilisation combined with no‐tillage or subsoiling produced greater SOC stocks at 0–35 cm depth compared to other treatments. No‐tillage increased labile C contents and CMI at 0–10 cm depth, while subsoiling increased labile C contents and CMI at 0–10 and 35–50 cm depths. Wheat yield and sustainable yield index (SYI) were positively correlated with SOC, and the effect of SOC contributed to SYI largely through indirect effects of dissolved organic C and particulate organic C. Wheat yield and SYI were increased by optimising fertilisation and tillage, and the greatest yield was under balanced fertilisation combined with the subsoiling treatment. Our findings suggested that balanced fertilisation combined with subsoiling was an effective practice for increasing SOC sequestration, soil quality, wheat yields and had great potential application on the Loess Plateau in China. Highlights: C sequestration under conservation tillage and fertilisation are controversial in semi‐arid areas.Balanced fertilisation promoted SOC sequestration in no‐tillage and subsoiling treatments.Subsoiling improved soil quality at 0–10 and 35–50 cm depths due to the greater SOC and labile C.Subsoiling was superior to no‐tillage and ploughing in maintaining crop productivity. [ABSTRACT FROM AUTHOR]

Afforestation of less productive, risky and degraded agricultural land is one of the methods which is recommended for practical agriculture to increase the carbon sequestration. In this study, we have attempted to determine the effect of afforestation of agricultural land (warm, mildly dry climatic region of the Czech Republic) on the soil organic carbon (Cox) concentrations in the mineral soil. Two soil types (Haplic Chernozem and Haplic Cambisol) were afforested. Both an indirect estimation (loss-on-ignition method) as well as chromsulfuric acid mixture oxidation were used to determine the organic carbon content in the soil samples and the methods were compared. In the case of the Haplic Chernozem, the Cox concentration at a depth of 0-10 cm after 1-3 years of afforestation with pedunculate oak or Scots pine significantly decreased (P < 0.01 and P < 0.004, respectively) with the stand age. Similar to the case of the Haplic Chernozem, the Cox concentration in the Haplic Cambisol also significantly decreased in the variants with Scots pine (P < 0.003) or a mixture of forest tree species (P < 0.006); no significant (P > 0.05) decrease was found in the case of a mixture of forest tree species on the Haplic Chernozem or with Douglas fir on the Haplic Cambisol. Significantly higher (P < 0.05) Cox concentrations were typically found in the case of 1-year-old stands compared to 2-year-old or 3-year-old stands. A higher Cox loss than the quantity of residues returned to the soils may be the reason the soil Cox concentration significantly (P < 0.00001 and P < 0.000001) decreased for the control agricultural plots (Haplic Chernozem and Haplic Cambisol). The carbon stock in the upper 10 cm of the 5-year-old stands was higher on the Haplic Chernozem and lower on the Haplic Cambisol compared to the control agricultural plots. [ABSTRACT FROM AUTHOR]

Nitrogen (N) is the prime nutrient for crop production and carbon-based functions associated with soil quality. The objective of our study (2012 to 2019) was to evaluate the impact of variable rates of N fertilization on soil organic carbon (C) pools and their stocks, stratification, and lability in subtropical wheat (Triticum aestivum)—mungbean (Vigna radiata)—rice (Oryza sativa L) agroecosystems. The field experiment was conducted in a randomized complete block design (RCB) with N fertilization at 60, 80, 100, 120, and 140% of the recommended rates of wheat (100 kg/ha), mungbean (20 kg/ha), and rice (80 kg/ha), respectively. Composite soils were collected at 0–15 and 15–30 cm depths from each replicated plot and analyzed for microbial biomass (MBC), basal respiration (BR), total organic C (TOC), particulate organic C (POC), permanganate oxidizable C (POXC), carbon lability indices, and stratification. N fertilization (120 and 140%) significantly increased the POC at both depths; however, the effect was more pronounced in the surface layer. Moreover, N fertilization (at 120% and 140%) significantly increased the TOC and labile C pools when compared to the control (100%) and the lower rates (60 and 80%). N fertilization significantly increased MBC, C pool (CPI), lability (CLI), and management indices (CMI), indicating improved and efficient soil biological activities in such systems. The MBC and POC stocks were significantly higher with higher rates of N fertilization (120% and 140%) than the control. Likewise, higher rates of N fertilization significantly increased the stocks of labile C pools. Equally, the stratification values for POC, MBC, and POXC show evidence of improved soil quality because of optimum N fertilization (120–140%) to maintain and/or improve soil quality under rice-based systems in subtropical climates. [ABSTRACT FROM AUTHOR]

Hyperspectral remote sensing technology can be used to monitor the soil nutrient changes in a rapid, real-time, and non-destructive manner, which is of great significance to promote the development of precision agriculture. In this paper, 225 soil samples were studied. The effects of different water treatments on soil organic carbon (SOC) content, and the relationship between SOC content and spectral reflectance (350–2500 nm) were studied. 17 kinds of preprocessing algorithm were performed on the original spectral (R), and the five allocation ratios of calibration to verification sets were set. Finally, the model was constructed by partial least squares regression (PLSR). The results showed that the effects of water treatment on SOC content were different in different growth stages of winter wheat. Results of correlation analysis showed that the differential transformation can refine the spectral characteristics, and improve the correlation between SOC content and spectral reflectance. Results of model construction showed that the models constructed by second-order differential transformation were not good. But the ratio of standard deviation to the standard prediction error (RPD) values of the models were constructed by simple mathematical transformation (T0–T5) and first-order differential transformation (T6–T11) can reach more than 1.4. The simple mathematical transformation (T0–T2, T4–T5) and the first-order differential transformation (T6–T10) resulted in the highest RPD in mode 5 and mode 2, respectively. Among all the models, the model of T7 in mode 2 reach the highest accuracy with a RPD value of 1.9861. Therefore, it is necessary to consider the data preprocessing algorithm and allocation ratio in the process of constructing the hyperspectral monitoring model of SOC. [ABSTRACT FROM AUTHOR]

Quantifying changes in soil biochemical properties is important in understanding the response to soil management practices. Our objectives were to evaluate the single and combined effects of three different crop rotations (maize (Zea mays)‐soybean (Glycine max) (2 years), maize‐soybean‐oat (Avena sativa) (3 years), maize‐soybean‐oat‐winter wheat (Triticum aestivum) (4 years)), and two winter cover‐type (cover crop and no cover crop) managements under long‐term conventional‐till (CT) and no‐till (NT) systems on water‐extractable carbon and nitrogen fractions, microbial biomass carbon (MBC) and enzymatic activities. The experimental site under silty clay loam in southeastern South Dakota was sampled before planting in early spring, after planting in early summer, and during the maize grain‐filling stage in early autumn of 2017, from the surface 0–7.5‐cm depth in 2017. In general, the cover crops had 9, 17 and 19% higher geometric mean of enzyme activities than the no‐cover‐crop plots at pre‐planting, after planting and the grain‐filling stage of maize, respectively. Although there were not many differences between "NT vs. CT" and "2‐year vs. 3‐year vs. 4‐year rotation" treatments, additive effects between "tillage and cover crops" and "rotation and cover crops" were observed. The MBC and β‐glucosidase activity were 31 and 54% higher, respectively, with cover crop vs. no cover crop under 4‐year rotation after planting of maize. Similarly, significant interactions between "cover crop and tillage" for hot water‐extractable nitrogen and urease activity at pre‐planting, and β‐D‐glucosidase after planting of maize, were observed. At the grain‐filling stage, the hot water‐extractable contents were significantly greater under cover crop as compared to the no‐cover‐crop plots. Furthermore, this study also concluded that seasonal fluctuations are important for understanding the management impacts on soil carbon fractions and biochemical properties. Highlights: Soil microbial properties responded differently to tillage, rotation and cover crops during the maize growing season.Residues produced by cover crops during winter fallow impacted soil functioning and interacted with other management factors (rotation and tillage system).Rotation impacted the carbon availability after planting, whereas tillage affected the enzyme activities.Winter cover crops influenced labile soil organic matter (SOM) and enzymatic properties after 4 years. [ABSTRACT FROM AUTHOR]

Long-term agricultural research with annual and perennial cropping systems provides significant insight into the carbon sequestration potential of agriculture in the East Mediterranean region of Anatolia. This study explored the effect of different application rates of phosphorus (P) fertilizer on the storage and quality of soil organic carbon (SOC) and soil CO2 flux to assess the relationship between SOC and P application. The study was based on the hypothesis that long-term P fertilization can affect carbon sequestration in soil and impact soil CO2 flux. The objectives of the present study were to: (i) analyze the effect of long-term inorganic chemical P fertilization on SOC content and (ii) estimate the effect of long-term P fertilization on CO2 flux. Under crop rotation, corn (Zea mays L.) and wheat (Triticum aestivum L.) (CW system) were exposed to four fertilizer doses (0, 50, 100, and 200 kg ha−1), which were repeated annually over 20 years. During plant growth, bare soil and treated soil CO2 fluxes were determined several times. The results demonstrated that P fertilizer did not have a direct impact on the SOC of the summer-maize growing season and had a positive impact on SOC during the winter-wheat growing season. P fertilization levels have positive impact on atmospheric CO2 capture and increased SOC content. [ABSTRACT FROM AUTHOR]

The performance of DNDC (DeNitrification-DeComposition) and RothC (Rothamsted Carbon model) in simulating soil organic carbon (SOC) storage in soils under rice (Oryza sativa L.) – wheat (Triticum aestivum L.), maize (Zea mays L.) – wheat and cotton (Gossypium hirsutum L.) – wheat cropping systems was evaluated on field and regional scale. Field experiments consisted of N, NP, NK, PK, NPK, FYM, N + FYM, NPK + FYM, and control (UF) treatments. DNDC and RothC over-estimated SOC storage by 0.35–1.16 Mg C ha−1 (6–21%) in surface layer with manure application, compared with inorganic fertilizer treatments by 1.01–1.16 Mg C ha−1 (14–18%). Although RothC only slightly over-estimated SOC stocks, DNDC provided a better match for measured versus simulated SOC stocks (R2 = 0.783*, DNDC; 0.669*, RothC, p <.05). Model validation on independent datasets from long-term studies on rice–wheat (R2 = 0.935**, DNDC; R2 = 0.920**, RothC, p <.01) and maize–wheat (R2 = 0.895** for DNDC and R2 = 0.967** for RothC, p <.01) systems showed excellent agreement between measured and simulated SOC stocks. On a regional scale, change in SOC storage under Scenario 1 (NPK) was significant up to 8 years of simulation, with no change thereafter. In Scenario 2 (NPK + FYM), DNDC simulated SOC storage after 10 years was 2.0, 0.4, and 1.4 Mg C ha−1 in three systems, respectively. Amount of C sequestered in silt + clay fraction varied between 0.31 and 0.97 kg C 10 years−1 (Mg silt + clay)−1 under Scenario 1, and between 0.78 and 2.67 kg C 10 years−1 (Mg silt + clay)−1 under Scenario 2. [ABSTRACT FROM AUTHOR]

BACKGROUND: An irrigation regime is an important factor in regulating soil CO2 emissions from wheat fields. Deficit irrigation can be applied easily in the fields and has been implemented in northwest China. Previous studies have mainly focused on the effects of deficit irrigation on crop yield and quality. Studies on its environmental impacts are sparse. RESULTS: Soil CO2 fluxes from deficit‐irrigated fields were lower than those from full irrigation (CK) during most of the growing season. Cumulative soil CO2 emissions from deficit‐irrigated fields were reduced by 10.2–25.5%, compared with the CK. Peaks of soil CO2 fluxes were observed 3–7 days after irrigation in the water‐filled pore space (WFPS) range of 65.7–80.4%. Under different irrigation regimes, significant positive correlations were observed between soil CO2 fluxes and WFPS (P < 0.01), but no significant correlations were found between soil CO2 fluxes and soil temperature. Compared to CK, yields for the T1, T2, and T4 were significantly reduced (P < 0.05) but the yield for T3 was only reduced by 2.3% (P > 0.05); T3 significantly reduced soil CO2 emissions by 10.2% (P < 0.05) and reduced the irrigation water amount by 5.7%. CONCLUSION: Deficit irrigation effectively reduced CO2 emissions from winter wheat field soils. T3 may be a water‐saving, CO2 emission‐reducing and high‐yield irrigation regime for winter wheat fields in northwest China. The research laid a preliminary theoretical foundation for formulating winter wheat irrigation systems that are water saving, emission reducing, and that produce high yields. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The objectives of this experiment were i) to study on the garbage composting to improve the soil organic carbon (SOC) pools (active and passive), ii) work out the carbon (C) budgeting, and iii) cut off C footprints (CFs) in the rice (Oryza sativa L.)-wheat (Triticum aestivum L.) farming to achieve the long-term sustainability. The main plots show four fertilizer levels (F0 = control, F1 = 112.5:45:45 kg nitrogen; phosphorus; potassium (NPK) ha−1, F2 = 150:60:60 kg NPK ha−1 and F3 = 150:60:60 kg NPK ha−1+ 5 kg iron (Fe) + 5 kg zinc (Zn) were applied, while in sub plots with the combination of three industrial garbage (I1 = carpet garbage; I2 = pressmud; I3 = bagasse) and three microbial culture (M1 = Pleurotus sajor-caju , M2 = A zotobacter chroococcum ; M3 = Trichoderma viride) made into nine treatment combinations were applied. Based on the interaction, treatment F3 × I1+M3 resulted in a maximum of 25.1 and 22.4 Mg ha−1 total CO 2 biosequestration by rice and wheat, respectively. However, it was cut off CFs by 29.9 and 22.2% more than F1 × I3+M1. Based on the soil C fractionation study, in the main plot treatment, F3 was active very labile C (VLC) and moderately labile C (MLC) and passive less labile C (LLC) and recalcitrant C (RC) SOC fractions contributed by 68.3 and 30.0%, respectively, of total SOC. However, in the sub plot, treatment I1+M3 found 68.2% and 29.8% active and passive SOC fractions, respectively, of total SOC. Regarding the soil microbial biomass C (SMBC) study, F3 had 37.7% higher than F0. However, in the sub plot, I1+M3 was seen to be 21.5% greater than I2+M1. Furthermore, wheat and rice had higher 1002 and 897 US$ ha−1 potential C credit in F3 × I1+M3, respectively. SOC fractions were perfectly positively correlated with SMBC. A positive (+) correlation was observed among grain yield (wheat and rice) and SOC pools in soil. However, a negative correlation was found between the C sustainability index (CSI) and greenhouse gas intensity (GHGI). The variability in wheat and rice grain yield was 46 and 74%, respectively, contributed by the SOC pools. Therefore, this study hypothesised that applying inorganic nutrients and industrial garbage converted into biocompost cut off C emissions and reduced the demand for chemical fertilizers, opening garbage disposal, and simultaneously enhancing the SOC pools. [ABSTRACT FROM AUTHOR]

The introduction of novel perennial grains into annual row crop rotations is proposed to increase soil ecosystem services and enhance plant-soil-microbial linkages because perennials provide deeper root systems and more continuous ground cover than annuals. While soil microbial communities underpin many ecosystem services, we know little about how soil microbial composition and diversity, and soil carbon storage, differ between soils of annual vs. perennial grain crops. We measured soil fungi: bacteria (F/B) ratios and soil carbon within the novel perennial intermediate wheatgrass (IWG; trademarked Kernza®) and tilled annual wheat and compared soil microbial diversity and community composition within their rhizosphere, shallow bulk soil (0–15 cm) and total bulk soil (0–90 cm). After three years, soil depth explained 30–40% and 12–22% of the variance in bacterial and fungal community composition, respectively, while crop type explained 10% and 9–16% of the variance, respectively. Fungal communities were most impacted by crop type in the rhizosphere and shallow bulk soil and less sensitive to differences in soil depth. In contrast, crop type had a smaller effect on bacterial communities which were more influenced by soil depth. IWG trended higher in soil carbon mass at 0–30 cm (p = 0.22) and had a higher (F/B) ratio than tilled annual wheat at depths below 15 cm, but tilled annual wheat had higher soil carbon concentration (p = 0.12) and soil carbon mass (p = 0.09) at the 60–90 cm soil depth. Our results indicate that fungi were more responsive than bacterial communities to crop type and that IWG has a higher fungal biomass and different fungal community composition than annual wheat at depth. However, despite these distinct differences in fungal communities in IWG compared to annual wheat, the differences did not translate into greater soil carbon mass in IWG at depth. • Annual and perennial grains host different soil microbial communities. • Microbial community composition is influenced more by soil depth than crop type. • Annual vs. perennial influences are stronger in fungal than bacterial communities. • IWG increases carbon in the topsoil, annual wheat increases carbon in subsoil. [ABSTRACT FROM AUTHOR]

• Tillage timing did not affect macronutrient in the soil over time. • No-tillage was better in maintaining nutrients in soil over time. • No-tillage had lower grain N than Spring or Fall tillage. Tillage is known to significantly affect crop residue decomposition and soil nutrient dynamics, but the impacts of tillage on soil and plant macronutrients concentration with time have not been reported. This study was conducted (i) to assess the influence of tillage timing and intensity on soil and wheat (Triticum aestivum L.) macronutrient concentration of a winter wheat-dry pea (Pisum sativum L.) rotation (WW-P) under a dryland cropping system, and (ii) to compare macronutrients in the tillage treatments with a nearby long-term grass pasture (GP). The tillage treatments were fall tillage (FT), spring tillage (ST), no-tillage (NT) and disk/chisel tillage (DT/CT). Soil samples from 1995, 2005, and 2015 were analyzed to determine the concentration of soil organic carbon (SOC), total N and S, Mehlich III extractable P, K, Ca, and Mg, and soil pH. The impact of tillage on soil macronutrient concentration was evident after 52 years of WW-P. As a result, greater concentration of SOC, total S, and extractable P, and K were observed under NT than under FT or ST. The WW-P plots lost 28, 46, and 67% of SOC, Mg, and S, respectively, in the top 10 cm of soil compared with the GP plots, whereas the NT plots were the only plots in WW-P to maintain a P concentration (99 mg P kg−1) comparable with GP plots (102 mg P kg−1) at the same depth. The results indicated that NT could be beneficial to recharge the soil nutrient pool over time compared to FT or ST. [ABSTRACT FROM AUTHOR]

Decline in soil organic carbon (SOC) due to intensive tillage and removal or burning of crop residues is considered a major threat to maintaining soil quality and meeting future challenges of food production at national and global scales. Adoption of conservation-agriculture practices (no till and residue retention) is necessary to promote soil structural stability and increases in SOC content and enzyme activities. We evaluated the impact of tillage and residue-management practices on yield, soil labile-C pools, aggregate stability and soil enzyme activities after seven cycles of a rice (Oryza sativa L.)–wheat (Triticum aestivum L.) system on the Indo-Gangetic Plain of India. Treatments included four combinations of tillage and crop establishment in rice (main plots), and three combinations of tillage and residue management in wheat (subplots). Irrespective of rice-establishment method, mean grain yield of no-till wheat with rice-residue mulch (NTW+RR) was 9% and 22% higher, respectively, than of conventional-till (CTW) or no-till wheat with no rice-residue mulch. Soil C pools (very labile, labile, less-labile and non-labile) were significantly higher under a no-till dry-seeded rice (NTDSR)–NTW+RR cycle than conventional-till puddled transplanted rice–CTW. Macro-aggregates (>0.25 mm) had higher labile C pools, glomalin content and enzyme activities than micro-aggregates. NTW+RR significantly increased soil C pools within both macro- and micro-aggregates. Compared with CTW, NTW+RR increased soil dehydrogenase, cellulase and alkaline phosphatase activities by 23%, 34% and 14%, and water-soluble organic C by 31%, and increased water-stable aggregates and mean-weight-diameter. NTDSR–NTW+RR increased SOC, enzyme activity, aggregate stability and wheat grain yield. Results indicated that soil labile-C pools across aggregate fractions were the most sensitive indicators of soil quality when determining the effects of changes in management practices. Furthermore, adoption of no till and residue retention may improve sustainability in rice–wheat systems of the Indo-Gangetic Plain. This 7-year study examined soil carbon pools, aggregate stability, enzyme activities and wheat yield under conservation and conventional tillage and residue-management practices in a rice–wheat system on the Indo-Gangetic Plain. Macro-aggregates (>0.25 mm) had higher labile C pools, glomalin content and enzyme activities than micro-aggregates. The combination of no-till direct-seeded rice with no-till wheat + rice residue increased SOC, soil enzyme activities, aggregate stability and wheat grain yield, indicating that adoption of no till and residue retention may improve sustainability in these rice–wheat systems. [ABSTRACT FROM AUTHOR]

Carbon (C) mineralization of crop residues is an important process occurring in soil which is helpful in predicting CO2 emission to the atmosphere and nutrient availability to plants. A laboratory experiment was conducted in which C mineralization of residues of rice (Oryza sativa), wheat (Triticum aestivum), maize (Zea mays), mungbean (Vigna radiata) and their mixtures was applied to the soil surface or incorporated into an Alfisols from Northwest India. C mineralization was significantly affected by residue placement and type and their interactions. Rice residue had a higher decomposition rate (k = 0.121 and 0.076 day−1) than wheat (0.073 and 0.042 day−1) and maize residues (0.041 day−1) irrespective of placements. Higher decomposition rates of rice and wheat were observed when placed on soil surface than incorporated in the soils. Additive effects of the contribution of each residue type to C mineralization of the residue mixture were observed. When mungbean residue was added to the rice/wheat or maize/wheat mixture, decomposition of the residue mixture was enhanced. Crop residues with low N and high C/N ratio such as maize, wheat, rice and their mixtures can be applied on the soil surface for faster C and N mineralization, thereby helping to manage high volumes of residues under conservation agriculture-based practices in northwest India. [ABSTRACT FROM AUTHOR]

Abstract Crop residue is a source of energy and nutrients for microbial growth, and can be converted into soil organic matter (SOM). However, there are still knowledge gaps on how the interaction of crop residue and supplementary nutrients (nitrogen, phosphorus and sulfur) influence the fate of residue in microbial biomass carbon (MBC) and microbial use efficiency. Here, we quantified the carbon (C) mineralization of wheat residue (δ13C 494‰) and microbial C use efficiency at ecosystem scale (CUE E) with two levels of the residue (6.7 and 20.0 g kg−1 soil) and three levels of nutrients in Luvisol and Vertisol under a controlled laboratory condition (22 °C). Between 48 and 61% of residue-C was mineralized over 245 days. The residue CUE E was similar across the two levels of the residue on day 3 (i.e. , 0.29–0.40 in the Luvisol and 0.41–0.50 in the Vertisol) and then decreased over time, likely because of greater increase in cumulative total respiration and microbial turnover, relative to microbial growth. The residue CUE E was 20–55% lower in the high-residue, compared with (cf.) low-residue, input after day 10, which may have resulted from the greater loss of C via overflow respiration (microbial respiration without the production of energy) and turnover of high MBC. Narrowing of the C-nutrient imbalance increased residue-C mineralization, residue-derived MBC, and residue CUE E only under the high-residue input scenario where nutrients were possibly a limiting factor for microbial growth. Consequently, the results indicate a higher efficiency of SOM formation from returning of residue to soils under (i) low-residue (cf. high-residue) with or without nutrients, and (ii) high-residue with nutrient inputs (cf. no nutrient). The findings of the integrated residue–nutrient management on dynamics of residue-derived MBC and residue CUE E can be used to improve predictive performance of the models on specific soil functions such as SOM storage in agro-ecosystems. Graphical abstract Image 1 Highlights • Examined integrated wheat residue-nutrient management on C dynamics in two soils. • Residue-C mineralization & MBC greater in soils with high (cf. low) residue input. • Microbial C use efficiency (CUE) greater in soils with low (cf. high) residue input. • Nutrient input increased C mineralization and MBC only under the high-residue input. • Nutrient input increased microbial CUE initially only under the high-residue input. [ABSTRACT FROM AUTHOR]

Agricultural production must increase to feed a growing and wealthier population, as well as to satisfy increasing demands for biomaterials and biomass-based energy. At the same time, deforestation and land-use change need to be minimized in order to preserve biodiversity and maintain carbon stores in vegetation and soils. Consequently, agricultural land use needs to be intensified in order to increase food production per unit area of land. Here we use simulations of AgMIP’s Global Gridded Crop Model Intercomparison (GGCMI) phase 1 to assess implications of input-driven intensification (water, nutrients) on crop yield and yield stability, which is an important aspect in food security. We find region- and crop-specific responses for the simulated period 1980–2009 with broadly increasing yield variability under additional nitrogen inputs and stabilizing yields under additional water inputs (irrigation), reflecting current patterns of water and nutrient limitation. The different models of the GGCMI ensemble show similar response patterns, but model differences warrant further research on management assumptions, such as variety selection and soil management, and inputs as well as on model implementation of different soil and plant processes, such as on heat stress, and parameters. Higher variability in crop productivity under higher fertilizer input will require adequate buffer mechanisms in trade and distribution/storage networks to avoid food price volatility. [ABSTRACT FROM AUTHOR]

This 2-year study aimed to verify whether the continuous application of no tillage (NT) for over 20 years, in comparison with conventional tillage (CT), affects nitrous oxide (N 2 O) and ammonia (NH 3 ) emissions from a Vertisol and, if so, whether such an effect varies with crop sequence (continuous wheat, WW and wheat after faba bean, FW). To shed light on the mechanisms involved in determining N-gas emissions, soil bulk density, water filled pore space (WFPS), some carbon (C) and nitrogen (N) pools, denitrifying enzyme activity (DEA), and nitrous oxide reductase gene abundance (nosZ gene) were also assessed at 0–15 and 15–30 cm soil depth. Tillage system had no significant effect on total NH 3 emissions. On average, total N 2 O emissions were higher under NT (2.45 kg N 2 O-N ha − 1 ) than CT (1.72 kg N 2 O-N ha − 1 ), being the differences between the two tillage systems greater in FW than WW. The higher N 2 O emissions in NT treatments were ascribed to the increased bulk density, WFPS, and extractable organic C under NT compared to CT, all factors that generally promote the production of N 2 O. Moreover, compared to CT, NT enhanced the potential DEA (114 vs 16 μg N kg − 1 h − 1 ) and nosZ gene abundance (116 vs 69 copy number mg − 1 dry soil) in the topsoil. Finally, NT compared to CT led to an average annual increase in C stock of 0.70 Mg C ha − 1 year − 1 . Though NT can increase the amount os soil organic matter so storing CO 2 into soil, some criticisms related to the increase of N 2 O emission arise, thereby suggesting the need for defining management strategies to mitigate such a negative effect. [ABSTRACT FROM AUTHOR]

Perennial grasses have been promoted to supply cellulose for ethanol production but possible consequences on soil organic carbon (SOC) should be assessed before adoption in a given region. Specific objectives were to (i) compare aboveground biomass C production and depth distribution of SOC content of continuous winter wheat (Triticum aestivum L.) and switchgrass (Panicum virgatum L.), (ii) determine the contribution of switchgrass to SOC, and (iii) characterize soil C inventories under each crop across a wide range of precipitation regimes. A 6-yr (2008–2013) field study with winter wheat and switchgrass ‘Blackwell’ was conducted in northeastern Oregon. Solid set sprinkler irrigation was used to create a productivity gradient of low, medium, and high precipitation levels. The contribution of switchgrass to SOC was identified with δ13C measurements. Winter wheat had significantly higher 5-yr-average aboveground biomass C production than switchgrass across precipitation levels and winter wheat under high precipitation produced significantly higher aboveground biomass C than medium and low precipitation. After 5-yr of cropping, SOC accrual in the 0- to 15-cm depth was significantly higher under winter wheat than switchgrass in each precipitation regime. Results of δ13C indicated switchgrass contributed 7.9, 8.5, and 12.9% to profile SOC at low, medium, and high precipitation levels. Soil organic carbon in dry cropland is resistant to a shift in crop species. Switchgrass does not increase SOC more than continuous winter wheat in dry cropland of the semiarid Pacific Northwest. [ABSTRACT FROM AUTHOR]

Aggregate-size classes may have different microbial accessibility and therefore different decomposability of aggregate-associated soil organic matter (SOM). However, processes and mechanisms of soil organic carbon (SOC) mineralisation and availability of nutrients [nitrogen (N), phosphorus (P) and sulphur (S)] in different aggregate-size classes, and particularly, the interaction of aggregates with tillage intensity and crop residue type in contrasting soils is poorly understood. Soil samples from conventional tillage (CT) and reduced tillage (RT) systems under mixed wheat–pasture farming, and no-till (NT) under continuous cereal–cover cropping in a Luvisol, and from CT and NT under continuous wheat cropping in a Vertisol, were separated into three dry aggregate classes of different sizes [mega-aggregates (>2–6.5 mm), macro-aggregates (0.25–2 mm) and micro-aggregates (<0.25 mm)]. Two residue types (canola and wheat stem; δ 13 C 124 and 460‰, respectively) were added into each of the three aggregate class samples from Luvisol (δ 13 C −24.7‰) and Vertisol (δ 13 C −18.5‰). Total CO 2 -C, δ 13 C in CO 2 -C, microbial biomass C (MBC), and plant available N, P and S were measured periodically during the 126-day incubation. The results showed that crop residue input increased native SOC mineralisation ( via positive priming), MBC and microbial metabolic quotient in all three aggregate-size classes from different tillage systems in both soils. Native SOC mineralisation was 1.5–3.7 and 0.6–2.8 times higher in the canola and wheat residue-amended ( cf . control, non-amended) aggregates, respectively. Native SOC mineralisatiion and MBC were higher in the macro- and micro- than mega-aggregates in both soils. However, priming of native SOC mineralisation, relative to the control, was similar across the aggregates, except for the CT in the Luvisol where priming was higher in the macro- than micro- and mega-aggregates. Native SOC mineralisation among the aggregate-size classes was 26–114% higher under CT or RT cf . NT in the Luvisol but was similar under CT and NT in the Vertisol. Net available N was significantly higher in the residue-amended than the control aggregates, particularly in the CT and/or RT versus the NT at day 30 only, and mainly in the Luvisol. Further, substantial amounts of available P and S were released from the residue-amended versus the control aggregates at day 126, with Vertisol releasing 2–3 times more available P than Luvisol. In conclusion, our findings showed the importance of returning crop residues to enhance nutrient availability from all aggregate-size classes in different soils and farming systems. In particular, the tillage ( versus no-till) and canola ( versus wheat) residue induced a greater release of nutrients, generally in the pattern of micro- ≥ macro- > mega-aggregates. Clearly, the input of crop residues enhanced the release of SOM-bound nutrients, possibly via positive priming, and may have mobilised mineral-bound nutrients, such as P and S in each aggregate-size class, with tillage intensity and soil type modulating these processes. [ABSTRACT FROM AUTHOR]

Background: Differences in cropping systems and their impacts on plant growth and carbon (C) uptake as well as soil C release pose a major challenge in projecting agroecosystem C balance. Methods: A four-year (2012-2015) field experiment was conducted to examine crop C uptake and soil respiration in two conventional (wheat-cotton and wheat-maize) and two legume-based (wheat-soybean and alfalfa-maize) double-season cropping systems in North China Plain. Results: During the 4 experimental years, crop C uptake was greater in the two conventional systems than the two legume-based systems. However, soil respiration was higher in the two systems with C (i.e. maize) than C crops (i.e. cotton and soybean) planted in summer. As consequences, cropland C balance was positive in the two conventional cropping systems, with greater value in the wheat-maize comparing to wheat-cotton system. However, the two legume-based cropping systems showed negative cropland C balance. Conclusions: Our findings indicate that, although more CO-C is emitted in maize-related cropping systems, the conventional agricultural activities may sequestrate more C in comparison with the legume-based farming in North China Plain due to higher C uptake, and highlight the importance of management strategy in improving agroecosystem C storage. [ABSTRACT FROM AUTHOR]

Straw return is a promising method for managing soil organic carbon (SOC) in agricultural soils and thus may promote sustainable land use. However, the optimal straw-return strategy for economically sustainable grain production in intensive winter wheat (Triticum aestivum L.)-summer maize (Zea mays L.) cropping systems remains uncertain. A 4-yr field experiment was conducted in the central North China Plain to determine the effects of straw return on SOC stock and lability, soil enzyme activity, and grain yield, and to further evaluate the sustainability of crop production in intensive wheat-maize double-cropping systems. Four treatments were tested: no straw return (NR), return of wheat straw (WR), return of maize straw (MR), and return of both wheat and maize straw (WR+MR). Compared with the initial value, SOC stocks significantly increased by 2.8, 5.4, and 13.1% in WR, MR, and WR+MR, respectively, and significantly decreased by 2.9% in NR. Stocks of KMnO4-oxidizable C and microbial biomass C; activities of soil invertase, protease, and dehydrogenase; and the C management index were significantly higher with than without straw return and followed the order NR < WR < MR < WR+MR. Yields of wheat and maize were highest in WR+MR, but economic sustainability was higher in WR and MR relative to NR and WR+MR. Our results indicate that return of either wheat or maize straw is sufficient to maintain SOC levels and may be the optimal strategy for economically sustainable grain production in the central North China plain. [ABSTRACT FROM AUTHOR]

[Display omitted] • OFS increased wheat yield and soil quality in two soils. • ROC, KOC, HKOC, and MKOC were the key fractions affecting SOC. • OFS increased SOC content by regulating KOCs transformation in two soils. • HKOC and MKOC can monitor and evaluate SOC and soil C pool changes. Organic fertilizer substitution (OFS) technology effectively mitigates the adverse effects of excessive synthetic fertilizer application while promoting soil organic carbon (SOC) sequestration in farmlands. However, how the permanganate oxidizable carbon fractions (KOCs) transformation affects SOC under OFS remains unknown. In this study, two typical farmland soils (grey desert soil, GS; meadow soil, MS) were selected for a 3-year field fertilization experiment (no fertilization, NF; synthetic fertilizer alone, SCF; and organic fertilizer substituted 20% synthetic N fertilizer, OFS). Field experiments conducted from 2018 to 2020 showed that SOC could be used to evaluate wheat yield and soil quality, so further study the effects of OFS on SOC and KOCs and their corresponding C pool management index (CPMIs). The results showed that OFS in GS and MS increased SOC (by 3.37%–15.62%, 4.92%–20.28%) and its fractions content (except low-activity KOC, LKOC) and CPMIs (except CPMI-L) year by year compared to SCF and NF. The recalcitrant organic C (ROC), KOC, high-activity KOC (HKOC), and medium-activity KOC (MKOC) were the key fractions affecting SOC. Moreover, HKOC and MKOC and their corresponding CPMIs (CPMI-H and CPMI-M) showed higher sensitivity. Structural equation modeling revealed that OFS in GS and MS increased SOC by increasing ROC and KOC (by regulating KOCs transformation) content, and increased CPMI-H and CPMI-M by increasing HKOC and MKOC content. Overall, the process of OFS promoted SOC sequestration and improved soil C pool in two soils were revealed from the perspective of KOCs transformation. Also, we proposed corresponding fertilization recommendations and showed that HKOC and MKOC could be used to evaluate and monitor soil quality and SOC. This study provides guidance for SOC sequestration, crop yield, and soil quality improvement in oasis wheat fields, contributing to the sustainable development of farmland. [ABSTRACT FROM AUTHOR]

The effect of integrated nutrient management practices on soil organic carbon (SOC) fractions, soil carbon (C) storage and grain productivity was investigated in winter wheat (Triticum aestivum) for two consecutive seasons (2013–2015). Fertility treatments were NPK as recommended inorganic fertilizer, NPK + cowdung, NPK + whole parts of the green manure plant Sesbenia aculeata , NPK + compost of Azolla caroliniana and NPK + rice husk dust. Application of NPK through inorganic fertilizer and in combination with organic amendments increased SOC and its active (microbial biomass C and dissolved organic C) and passive carbon fractions (humic and fulvic C, recalcitrant C). Application of organics with inorganic fertilizers resulted in greater soil C accumulation over inorganic fertilizer alone. Greater proportion (46%) of oxidizable organic C in the less labile fraction (F3) and recalcitrant fraction (F4) were found in the soil due to NPK + Azolla compost application. Higher concentration of microbial biomass C (MBC) was recorded at NPK + cowdung and NPK + Sesbenia aculeata . The trends in dissolved organic C (DOC) are similar to trends with the soil labile C pool (F1 and F2). Principal component analysis (PCA) demonstrated a close association among the recalcitrant C fraction, humic and fulvic C and the degree of humification of SOC. These fractions were apparently transformed more slowly in the soil and persisted for longer when Azolla compost was added. Azolla compost application with inorganic fertilizer (NPK) may therefore be a good strategy for reducing carbon dioxide (CO 2 ) in the atmosphere through increased flag leaf photosynthesis and by formation of stable humified substances in the soil without compromising the grain productivity. The amendments significantly increased the photosynthetic rate of wheat in reproductive growth stage. Grain yield was increased 27% due to NPK + Azolla compost application compared to control (NPK). The inorganic and organic amendments tested in this study enhanced soil C storage and plant C fixation in a continuous winter-wheat cropping system in India. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the changes in soil organic carbon (SOC) stock in relation to the carbon (C) input from nine wheat-based cropping systems and untilled grass. The SOC pool ranged from 32.1 to 49.4 Mg ha−1at 0–20 cm and from 94 to 171 Mg ha−1at 0–100 cm for the arable soil, while in untilled grassland, it was higher (54 and 185 Mg C ha−1, respectively). SOC stock was observed to be lower at the unfertilized 2-year rotation and higher at the 4-year rotation with manure and mineral fertilization. The study showed a winter wheat yield decrease of 176.8 kg ha−1for a 1- Mg ha−1SOC stock change in the 0–20-cm soil depth. The estimated C input for SOC stock maintenance was from 266 to 340 g C m−2 year−1for winter wheat and rotations, respectively. Additional C input did not increase the SOC pool, suggesting that arable plots had a limited ability to increase SOC. These results provide guidance for the selection of management practices to improve C sequestration. [ABSTRACT FROM PUBLISHER]

Background and aims: Soil degradation is a major global problem; to investigate the potential for recovery of soil biota and associated key functions, soils were monitored during the early years of conversion between permanent grassland, arable cropping and bare fallow (maintained by regular tilling). Distinct differences in soil properties had become apparent 50 years after a previous conversion. Methods: Subplots on previously permanent grassland, arable and bare fallow soil were converted to the two alternatives, generating 9 treatments. Soil properties (soil organic carbon, mesofauna, microbial community structure and activity) were measured. Results: After 2 years, mesofauna and microbial abundance increased where plants were grown on previously bare fallow soils and declined where grassland was converted to bare fallow treatment. Overall prokaryote community composition remained more similar to the previous treatments of the converted plots than to the new treatments but there were significant changes in the relative abundance of some groups and functional genes. Four years after conversion, SOC in arable and bare fallow soils converted to grassland had increased significantly. Conclusions: Conversion to permanent grassland effectively replenished C in previously degraded soil; the soil microbiome showed significant conversion-related changes; plant-driven recovery was quicker than C loss in the absence of plants. [ABSTRACT FROM AUTHOR]

Organic reduced tillage aims to combine the environmental benefits of organic farming and conservation tillage to increase sustainability and soil quality. In temperate climates, there is currently no knowledge about its impact on greenhouse gas emissions and only little information about soil organic carbon (SOC) stocks in these management systems. We therefore monitored nitrous oxide (N 2 O) and methane (CH 4 ) fluxes besides SOC stocks for two years in a grass-clover ley – winter wheat – cover crop sequence. The monitoring was undertaken in an organically managed long-term tillage trial on a clay rich soil in Switzerland. Reduced tillage (RT) was compared with ploughing (conventional tillage, CT) in interaction with two fertilisation systems, cattle slurry alone (SL) versus cattle manure compost and slurry (MC). Median N 2 O and CH 4 flux rates were 13 μg N 2 O-N m −2 h −1 and −2 μg CH 4 C m −2 h −1 , respectively, with no treatment effects. N 2 O fluxes correlated positively with nitrate contents, soil temperature, water filled pore space and dissolved organic carbon and negatively with ammonium contents in soil. Pulse emissions after tillage operations and slurry application dominated cumulative gas emissions. N 2 O emissions after tillage operations correlated with SOC contents and collinearly to microbial biomass. There was no tillage system impact on cumulative N 2 O emissions in the grass-clover (0.8–0.9 kg N 2 O-N ha −1 , 369 days) and winter wheat (2.1–3.0 kg N 2 O-N ha −1 , 296 days) cropping seasons, with a tendency towards higher emissions in MC than SL in winter wheat. Including a tillage induced peak after wheat harvest, a full two year data set showed increased cumulative N 2 O emissions in RT than CT and in MC than SL. There was no clear treatment influence on cumulative CH 4 uptake. Topsoil SOC accumulation (0–0.1 m) was still ongoing. SOC stocks were more stratified in RT than CT and in MC than SL. Total SOC stocks (0–0.5 m) were higher in RT than CT in SL and similar in MC. Maximum relative SOC stock difference accounted for +8.1 Mg C ha −1 in RT-MC compared to CT-SL after 13 years which dominated over the relative increase in greenhouse gas emissions. Under these site conditions, organic reduced tillage and manure compost application seems to be a viable greenhouse gas mitigation strategy as long as SOC is sequestered. [ABSTRACT FROM AUTHOR]

Lime application is the most common method to improve crop production in acid soils and has been shown to change soil organic C content. However, the impact of liming history on the priming effect on soil organic C is not well understood. This study examined the effect of liming history on C priming in response to the addition of crop residues of different qualities. Soils with pH ranging from 4.7 to 7.4 were collected from two adjacent field experiments whereby lime was applied at different rates, 6 and 35 years ago. A 90-day incubation study was conducted by applying C-labelled wheat (C/N 42) and field-pea (C/N 29) residues at a rate of 5 g kg soil. Residue application to soils yielded the positive priming effect in all pH levels with the magnitude of C priming being the greatest at initial soil pH 6.6. In comparison, the optimal pH for residue decomposition (7.3) was higher than that for priming. The overall priming effect was about 17% greater with field-pea than wheat residue. However, cumulative decomposition of added field-pea residue was 15% lower than that of wheat residue. Furthermore, C priming was greater in soils from the 35-year-old than the 6-year-old limed plots, indicating that a longer history of liming did not enhance the protection of indigenous C from mineralization. The results suggest that increases in soil pH by liming enhanced native C priming through greater microbial biomass and activity and that the magnitude and dynamics of the priming effect largely depended on residue quality and its consequent nutrient supply to decomposer organisms. The study implies that over-liming would likely have negative impacts on the long-term C sequestration. [ABSTRACT FROM AUTHOR]

Aims: The study aimed to find soil parameters that are best related to Se plant uptake for low Se soils with predominantly organic Se, and to explore the mechanisms that control Se bioavailability in the soils under study. Methods: A pot experiment using nineteen soil samples taken from different fields of arable land (potato fields) in the Netherlands was conducted on summer wheat ( Triticum aestivum L.). Selenium in wheat shoots and soil parameters, including basic soil properties, C:N ratio, inorganic selenite content, and Se and organic C in different soil extractions (0.01 M CaCl, 0.43 M HNO, hot water, ammonium oxalate, aqua regia) were analysed. Regression analysis was performed to identify soil parameters that determine Se content in wheat shoots. Results: The regression model shows that Se:DOC ratio in 0.01 M CaCl soil extraction explained about 88 % of the variability of Se uptake in wheat shoots. Selenium uptake increased with Se:DOC ratio in CaCl extraction, which can be interpreted as a measure of the content of soluble Se-rich organic molecules. Selenium:DOC ratio in CaCl extraction and Se uptake increased towards higher soil pH and lower soil C:N ratio. The soil C:N ratio is also negatively correlated to Se:organic C ratio in other extractions (0.43 M HNO, hot water, ammonium oxalate, aqua regia), indicating that at low soil C:N ratio soil organic matter is richer in Se. Contrarily, the soil pH is positively and strongly correlated to Se:organic C ratio in CaCl and hot water extractions, but only weakly correlated to Se:organic C ratio in other extractions. Conclusions: Selenium-rich dissolved organic matter is the source of bioavailable Se in low Se soils with predominantly organic Se. The soil pH and quality of soil organic matter (i.e. soil C:N ratio) are the main soil properties determining Se bioavailability in these soil types. [ABSTRACT FROM AUTHOR]

The maintenance and accumulation of soil organic carbon (SOC) in agricultural systems is critical to food security and climate change, but information about the dynamic trend and efficiency of SOC sequestration is still limited, particularly under long-term fertilizations. In a typical Purpli-Udic Cambosols soil under subtropical monsoon climate in southwestern China this study thus estimated the dynamic, trend and efficiency of SOC sequestration after 22-year (1991-2013) long-term inorganic and/or organic fertilizations. Nine fertilizations under a rice-wheat system were examined: control (no fertilization), N, NP, NK, PK, NPK, NPKM (NPK plus manure), NPKS (NPK plus straw), and 1.5NPKS (150% NPK plus straw). Averagely, after 22-years SOC contents were significantly increased by 4.2-25.3% and 10.2-32.5% under these fertilizations than under control conditions with the greatest increase under NPKS. The simulation of SOC dynamic change with an exponential growth equation to maximum over the whole fertilization period predicted the SOC level in a steady state as 18.1 g kg−1 for NPKS, 17.4 g kg−1 for 1.5NPKS, and 14.5-14.9 g kg−1 for NK, NP, NPK, and NPKM, respectively. Either inorganic, organic or their combined fertilization significantly increased crop productivity and C inputs that were incorporated into soil ranging from 0.91 to 4.63 t (ha · y)−1. The C sequestration efficiency was lower under NPKM, NPKS, and 1.5NPKS (13.2%, 9.0%, and 10.1%) than under NP and NPK (17.0% and 14.4%). The increase of SOC was asymptotical to a maximum with increasing C inputs that were variedly enhanced by different fertilizations, indicating an existence of SOC saturation and a declined marginal efficiency of SOC sequestration. Taken all these results together, the combined NPK plus straw return is a suitable fertilizer management strategy to simultaneously achieve high crop productivity and soil C sequestration potential particularly in crop rotation systems. [ABSTRACT FROM AUTHOR]

Summer fallow – the practice of keeping a field out of production during the growing season – is a common practice in dryland wheat ( Triticum aestivum L.) cropping systems to conserve soil water resources. Fallow also depletes soil carbon stocks and thereby soil quality. The area of summer fallow has decreased by tens of millions of hectares since the 1970s in the northern North American Great Plains as producers have recognized that avoiding fallow usually confers both economic and soil conservation benefits. Observed summertime cooling across parts of this region has coincided with fallow reduction, suggesting that the role of fallow in atmospheric processes needs to be ascertained. We measured carbon dioxide, latent heat, and sensible heat flux across a winter wheat – spring wheat – fallow sequence in Montana, USA to determine the effects of dryland crop management on ecosystem carbon resources and energy partitioning at the surface-atmosphere interface. Winter wheat and spring wheat fields were carbon sinks ( F c = −203 ± 52 g C CO 2 m −2 and −107 ± 29 g C CO 2 m −2 ), respectively, during the April to September study period, but the fallow field was a carbon source of 135 ± 73 g C CO 2 m −2 . Evapotranspiration in the wheat crops was over 100 mm greater than the 275 ± 39 mm observed in the fallow field during the study period. Modeled maximum daily atmospheric boundary layer height was on average 210 m higher and up to 900 m higher in fallow compared to the spring wheat field with more crossings of the modeled atmospheric boundary layer and lifted condensation level, suggesting that regional studies of the effects of fallow on near-surface temperature and moisture are necessary to understand the effects of fallow reduction on regional climate dynamics. Results demonstrate that fallow has a detrimental impact to soil carbon resources yet is less water intensive, with consequences for regional climate via its impacts on atmospheric boundary layer development and global climate via its carbon metabolism. [ABSTRACT FROM AUTHOR]

Diversification of conventional food-based cropping system with multipurpose lignocellulosic crops could increase biodiversity, farmer's market opportunities, feedstock for biorefineries, though can also imply soil organic carbon (SOC) stock changes, without competing with food production. Sunnhemp (Crotalaria juncea L.), biomass sorghum (Sorghum bicolor L.), kenaf (Hibiscus cannabinus L.), and industrial hemp (Cannabis sativa L.) are annual high yielding lignocellulosic crops with great potential for their multiple applications. The objective of the present study was to identify the SOC changes when the aforementioned crops are grown during the fallow periods of a conventional maize (Zea mays L.)-wheat (Triticum aestivum L.) rotation over five years. For this purpose, the SOC, carbon inputs (i.e. above and belowground residues), soil respiration, and cumulative CO 2 emissions were evaluated. The experiment was carried out in northern Italy (44°30′ N, 11°21′ E) from 2016 to 2021 in a randomized complete block design (n = 4) by adopting conventional field and harvest management practices (i.e. straw removal with hay machineries and alternating conventional with minimum tillage). The SOC stock increased by 7% from 2016 (56 Mg ha−1) to 2021 (60 Mg ha−1), regardless of the rotation system. Despite one of the highest CO 2 cumulative soil emissions (11 Mg ha−1 , two and three times higher than sunnhemp, kenaf, and industrial hemp, respectively) the rotation including biomass sorghum ended with higher SOC concentration (7.6 g kg−1) compared with industrial hemp (7 g kg−1) and kenaf (6.9 g kg−1), whereas fallow (7.2 g kg−1) and sunnhemp (7.1 g kg−1) showed intermediate values. The combination of high aboveground residues and high nitrogen fertilizations are deemed to act primarily on SOC level compared with belowground residues. In summary, the crop intensification did not deplete SOC, moreover biomass sorghum cropping system outperformed kenaf and industrial hemp through the decomposition into SOC of higher released residues. The rotation including sunnhemp coupled high SOC levels with low CO 2 emissions, raising interest in the light of its nitrogen fixing ability which can further help reducing the system's carbon footprint. • Cropping systems with wheat and maize including lignocellulosic crops during the fallow period are presented. • Over five years, the SOC carbon stock increased by 7%, regardless of rotation. • The rotation resulting with the highest SOC concentration included biomass sorghum (7.6 g kg−1). • The rotation resulting with the lowest SOC concentration included industrial hemp (7 g kg−1), and kenaf (6.9 g kg−1). • Aboveground crop residues, reduced tillage and nitrogen fertilization are likely the main drivers influencing SOC. [ABSTRACT FROM AUTHOR]

Quantifying changes in soil organic carbon (SOC) is essential for understanding the effect of managements on carbon (C) sequestration, especially in cultivated marginal lands. The objectives of this study were to determine the short- (<3 yr) and long-term (>24 yr) effects of a one-time compost application on soil organic matter (SOM) pools and stocks: coarse particulate organic matter (cPOM), fine particulate organic matter (fPOM), mineral-associated organic matter (MAOM), and soil physical quality (SOC:clay ratio) in surface- and sub-soils. Manure compost (0, 25, and 50 Mg dry weight ha–1) was applied to three organic dryland winter wheat-fallow systems (WW-F): Historic, (HT, >24 yr), Snowville (SN, < 3 yr), and Blue Creek (BC, <3 yr), in northern Utah. At HT, cPOM-C concentrations in amended plots were higher than under the control plots at the 0–10- (84.6 vs 54.4 g OC kg-1 fraction) and 10–30-cm (34.4 vs 19.4 g OC kg-1 fraction) depth. Compared to control plots, compost increased MAOM-C concentration from 1.8 to 3.4 g OC kg-1 fraction at the 30–60-cm at SN and from 2.35 to 3.99 g OC kg-1 fraction at the 60–90-cm depth at BC. Similarly, cPOM-C concentration was also increased at SN (5.5–23.6 g OC kg-1 fraction, 30–60-cm) and BC (8.3–31.2 g OC kg-1 fraction, 60–90-cm). The SOC:clay ratio was significantly higher at the 30–60-cm depth at BC (1:50–1:40) and at the 60–90-cm depth at SN (1:70–1:30), which suggests that compost application can impact subsoil physical quality. Thus, one-time compost application at 16.5 Mg C ha-1 every two decades might constitute a reasonable management option for managing C in dryland WW-F agroecosystems. • Effect of a one-time compost application on particulate organic matter is detectable 24 years later. • A one-time compost application moderately improves subsoil organic carbon. • Application of compost can enhance subsoil quality in non-irrigated dryland soils. [ABSTRACT FROM AUTHOR]

Introduction: 14th Line, "The variation between C3 (~ 27%) and C4 (~ 13%)"; Page no: 2, 1st line "ranging from - 23 - - 40% ... from - 9 to - 19%". 2nd page under title: Materials and methods (Soil sample and analysis): 15th line " SP 13 sp C3 and SP 13 sp C4 are - 27% and - 13%". [Extracted from the article]

Changes in field management and climate will alter soil organic carbon (SOC) and nitrogen (SN) cycling in the coming decades. This study is to quantify the effects of various fertilisation strategies and climate change scenarios on crop yield, and soil C and N cycling by the end of this century. Data from a long-term experiment with a winter-wheat ( Triticum aestivium L.) and summer maize ( Zea mays L.) rotation in Northern China was used to calibrate and validate the SPACSYS model. Five fertiliser practices were used: control (CK); combined mineral nitrogen, phosphorus and potassium (NPK); NPK plus manure (NPKM); high application rate of NPK fertilisers plus manure (hNPKM) and NPK with straw incorporation (NPKS). Crop yields, and SOC and SN stocks by 2100 were predicted under four climate scenarios (Baseline, RCP2.6, RCP4.5 and RCP4.5). Results showed that the SPACSYS model can adequately simulate the dynamics of SOC and SN stocks and the yields of winter wheat and summer maize. An application of NPK plus manure or straw not only enhanced crop yield, but also substantially increased SOC and SN stocks. The predictions showed the positive effects of fertilisation and climate change on crop yields and SOC stocks compared with those under the baseline. However, SN stock under the RCP8.5 decreased by 3–14% by 2100 for various fertilisation strategies compared with that under the baseline. On the other hand, mineral fertiliser plus manure led to a higher soil respiration rate and nitrogen losses through leaching and surface runoff under all the climate scenarios. Therefore, application of mineral fertilisers plus manure could enhance crop productivity and sustain soil fertility but cause more carbon emitted to the atmosphere and nitrogen losses. More attention should be paid on optimising fertilisation in order to increase crop productivity while minimising environmental risks. [ABSTRACT FROM AUTHOR]