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Background and aims Soil autotrophic microorganisms play crucial roles in carbon fixation and crop productivity. However, the information is remains limited to whether and how soil autotrophic microbe mediate SOC pool dynamics and crop productivity.Methods Here, we investigated the effects of the structure and co-occurrence network of soil autotrophic bacterial community on SOC storage and maize yield. A long-term field experiment was conducted with four chemical nitrogen (N) application rates on the semi-arid Loess Plateau, including N application at 0 kg ha–1 (N0), 100 kg ha−1 (N1), 200 kg ha−1 (N2), and 300 kg ha−1 (N3), respectively. Results Our results showed that the N application significantly impacted the structure and co-occurrence network of soil cbbL-carrying bacterial community via changing soil pH, nitrate nitrogen (NO3-N), and soil water content (SWC). The diversity of soil autotrophic bacterial community decreased with the increasing rate of N application. We detected a high abundance of the autotrophic bacterial dominant genera Xanthobacter, Bradyrhizobium, Aminobacter, and Nitrosospira. The co-occurrence network of autotrophic bacteria contained four distinct modules that consisted of closely interconnected microorganisms. Structural equation modeling further indicated that the diversity, composition, and network of autotrophic bacterial community had significant relationships with SOC storage and maize yield.Conclusion Taken together, our results highlight that the soil autotrophic bacterial community may drive carbon fixation SOC accumulation and contribute positively to crop productivity.

Increasing agricultural productivity without undermining further the integrity of the Earth’s environmental systems such as soil water balance are important tasks to ensure food security for an increasing global population in rainfed agriculture. The impact of intercropping maize (Zea mays L.) with potato (Solanum tuberosum L.) on yield, land equivalent ratios (LER), water equivalent ratio (WER), water use, energy output, and net economic return were examined under seven planting systems: potato grown solely or intercropped on the flat field without mulching, maize grown solely or intercropped with potato on ridges or flat field with or without plastic film mulched. The three intercropping systems had 3–13% less water use than the monocropping. Among the intercropped systems, flat field caused more depletion of soil water than ridged field for both years. Compared to monocultures, intercropping with plastic film mulching and ridging significantly increased LER and WER. Meanwhile, intercropping with mulching and ridging significantly increased net economic return and energy output by 8% and 24%, respectively, when compared to monocropping. These results suggest that maize under plastic film mulched ridge-furrow plot intercropped with potato under flat plot without mulching increased energy output, net economic return, and water use efficiency without increasing soil water depletion, which could be an optimal intercropping system for the semiarid farmland on the western Loess Plateau.

Water availability is a major constraint for crop production in semiarid environments. The impact of tillage practices on water potential gradient, water transfer resistance, yield, and water use efficiency (WUEg) of spring wheat was determined on the western Loess Plateau. Six tillage practices implemented in 2001 and their effects were determined in 2016 and 2017 including conventional tillage with no straw (T), no-till with straw cover (NTS), no-till with no straw (NT), conventional tillage with straw incorporated (TS), conventional tillage with plastic mulch (TP), and no-till with plastic mulch (NTP). No-till with straw cover, TP, and NTP significantly improved soil water potential at the seedling stage by 42, 47, and 57%, respectively, root water potential at the seedling stage by 34, 35, and 51%, respectively, leaf water potential at the seedling stage by 37, 48, and 42%, respectively, tillering stage by 21, 24, and 30%, respectively, jointing stage by 28, 32, and 36%, respectively, and flowering stage by 10, 26, and 16%, respectively, compared to T. These treatments also significantly reduced the soil&ndash, leaf water potential gradient at the 0&ndash, 10 cm soil depth at the seedling stage by 35, 48, and 35%, respectively, and at the 30&ndash, 50 cm soil depth at flowering by 62, 46, and 65%, respectively, compared to T. Thus, NTS, TP, and NTP reduced soil&ndash, leaf water transfer resistance and enhanced transpiration. Compared to T, the NTS, TP, and NTP practices increased biomass yield by 18, 36, and 40%, grain yield by 28, 22, and 24%, and WUEg by 24, 26, and 24%, respectively. These results demonstrate that no-till with straw mulch and plastic mulching with either no-till or conventional tillage decrease the soil&ndash, leaf water potential gradient and soil&ndash, leaf water transfer resistance and enhance sustainable intensification of wheat production in semi-arid areas.

It is critical to understand how farming practices affect the carbon and nitrogen footprints of agricultural production. Grain yield, economic return, and carbon and nitrogen footprints of spring wheat (Triticum aestivum L.) were examined under different tillage-mulch practices. Wheat was grown over 15 years (2002–2016) in the semi-arid region of the western Loess Plateau of China under six tillage-mulch practices: traditional plough with no straw mulching (T), no-till without straw mulching (NT), traditional plough with straw mulching (TS), no-till without straw mulching (NTS), traditional plough with plastic mulching (TP), no-till with plastic mulching (NTP). Average wheat yield over 15 years under NTS, NTP, TP and TS was increased by 28, 24, 22, and 13%, respectively, compared to T. Average net return was greatest under NTS and lowest under TP. The soils under all six tillage-mulch practices gained a considerably large amount of soil organic carbon (SOC) over the 15 yr. The increase in SOC in the 0–30 cm soil layer was greatest under NTS and lowest under T. When changes in soil C were included in the calculations, treatments of NT, TS, NTS, and NTP sharply reduced total greenhouse gas (GHG) emission compared to T. Compared to T, the carbon footprint was decreased by 180, 44, and 123% under NTS, NT, and TS, respectively, but was increased by 153% under TP. Compared to T, the nitrogen footprint was 24–26% lower in TP and NTP, but was not significantly different under NTS, NT, and TS. Therefore, NTS enhanced yield and net return, and reduced GHG and the carbon footprint without increasing the nitrogen footprint, and should be adopted to mitigate the environmental impacts of wheat production in the semiarid Loess Plateau.

Water availability is a major constraint for crop production in the Loess Plateau of China; thus, improving water use efficiency (WUE) is a main research target. The impact of alfalfa (Medicago sativa L.) growing age on forage yield, WUE, soil water storage, and soil fertility were examined in a 15-yr study in the western Loess Plateau of China. The results of this study indicate that long-term continuous production of alfalfa aggravated the soil water deficit and reduced soil available phosphorus (AP) and the ratio of soil organic carbon to soil total nitrogen, but increased soil organic carbon, soil total nitrogen, and the ratios of soil organic carbon to soil available phosphorus and soil total nitrogen to soil total phosphorus. After the ninth year of alfalfa production, the greatest soil water storage deficit degree was found in the 0–80 cm soil layer (63 %), followed by the 200–300 (57 %) and 80–200 cm (55 %) soil layers. Forage yield and WUE of alfalfa reached their greatest values following six- to nine-yr-old stands, and then decreased gradually. These results suggest that the yield decline with long-term stands of alfalfa may be related to reductions in soil water storage and AP, and their interaction, and the optimal alfalfa growing age should not extend beyond nine years in semiarid conditions.

SUMMARYSoil quality indicators (SQI) can be used as a synthetic tool for the assessment of the sustainability of agricultural systems. In this study, we developed SQI using minimum data set (MDS) and determined the response of SQI to long-term tillage systems. Field pea (Pisum sativumL.) and spring wheat (Triticum aestivumL.) were grown in alternate years at northwestern China, and soil attributes and crop productivity were measured 6 years after the initiation of the experiment. The MDS used to develop the SQI included soil physical (aggregate, bulk density, capillary porosity, field capacity), chemical (soil organic matter, total nitrogen, available phosphorus, available potassium) and biological (microbial count, microbial biomass, and the activities of catalase, urease, alkaline phosphatase, and invertase) properties. All the property variables were measured in each of the 0–5, 5–10 and 10–30 cm depths and those variables that contributed significantly to the SQI were selected to be included in the MDS. Amongst the measured variables, bulk density and microbial counts occurred in the MDS of all the three depths, suggesting that these two properties are highly affected by the tillage treatments. In the long-term field experiment, the no-till with stubble covering the soil surface treatment received the greatest SQI score and achieved the highest crop yield. Soil quality under tillage systems can be assessed adequately using MDS measured at the top soil (0–5 cm) layer in rainfed agro-ecosystems.

Greenhouse gas emissions from agriculture production are predicted to increase as the world’s population and demand for food increases. This research assessed the influence of tillage systems on CO2, N2O and CH4 fluxes and soil properties in spring wheat–field pea sequence in a rain-fed semi-arid environment. The tillage practices included; conventional tillage with straw removed (T), no–till with straw removed (NT), no-till with straw retention on the soil surface (NTS) and conventional tillage with straw incorporated (TS). Greenhouse gas emissions were monitored during the 2013, 2014 and 2015 cropping seasons using a carbon dioxide analyzer and static chamber-gas chromatography. Although the results showed that all treatments served as sources of atmospheric CO2 and N2O, and a sink of atmospheric CH4, CO2 and N2O emissions significantly decreased by 21 and 34 % in NTS sites, and CH4 uptake increased by 22 % compared with T fields. Soil organic carbon (0–30 cm) increased by 24, 19 and 7 % in NTS compared to T, NT and TS respectively. In addition, the contribution to increase soil organic carbon was much higher under straw retention treatments. T plots significantly increased global warming potential by 37 and 30 % in N2O and CH4 versus NTS soils. NTS increased straw and grain yield compared with straw removal treatments (NT and T), but that had no effect compared with TS treatment. NTS farming practices demonstrated increases in crop productivity and reduced greenhouse gas under dryland cropping systems.

After widespread application of the fully mulched ridge-furrow system, maize (Zea mays L.) has become a newly dominant crop in the semiarid Loess Plateau of China. Maximization of water use efficiency (WUE) through optimal farming practice are of great importance for sustainable intensification of maize production in this region. In this study, the impact of different tillage practices on soil quality, soil water, grain yield, WUE, and net economic return in a fully mulched ridge-furrow system were examined in a five-year field experiment, to optimize tillage practice for maize production in the area. Four tillage practices (CT, conventional tillage; NT, no-tillage; RT, rotary tillage; SS, subsoiling) were assessed. Compared to CT, SS reduced soil bulk density and penetration resistance, and increased saturated hydraulic conductivity and the percentage of macro-aggregates (≥ 0.25 mm) in the 0–30 cm soil layers, but NT and RT had the opposite effects to above soil physical properties except for macro-aggregates. Tillage practice did not significantly affect soil water storage, evapotranspiration, but annual soil water balance was lowest under SS, followed by CT, NT, and RT. SS increased soil organic C, mineral N and available P at 0−30 cm soil layer compared to CT. Grain yield and WUE under SS were increased by 12 and 15 % compared to CT, NT and RT had no significant effect on grain yield and WUE. Net economic return under NT and SS were increased by 42 and 23 % respectively compare to CT. These results demonstrated that subsoiling could improve grain yield, WUE, and net economic return of dryland maize by improving soil quality and mitigating soil water depletion. In the long-run, although no-tillage increased net economic return, it may not be sufficient to maintain yield and WUE due to deteriorated soil properties and accelerated soil water depletion. Thereby, subsoiling is optimal tillage practice for sustainable intensification of maize production in the semiarid Loess Plateau of China.

Drought is a major limiting factor for rainfed spring wheat production on the semiarid Loess Plateau of China. Suitable tillage practices are important for improving precipitation use efficiency (PUE), which is the ratio of grain yield to annual precipitation. To obtain a better understanding of the effects of conservation tillage practices on PUE on the semiarid Loess Plateau, PUE was divided into five steps: precipitation storage efficiency, farmland water consumption rate, ratio of transpiration to evapotranspiration, crop transpiration efficiency, and harvest index. Six tillage practices were assessed in this paper, including conventional tillage with no straw (T), no-till with straw cover (NTS), no-till with no straw (NT), conventional tillage with straw incorporated (TS), conventional tillage with plastic mulch (TP), and no-till with plastic mulch (NTP), based on a long-term experiment initiated in 2001. The impact of tillage practices on soil quality, soil water storage, soil evaporation, biomass yield, and grain yield of spring wheat were monitored in 2015 and 2016. The results show that NTS improved soil quality and soil water storage before sowing. No-till with plastic mulch and NTS increased evapotranspiration but decreased evaporation, thus optimizing precipitation storage efficiency, the farmland water consumption rate, the ratio of transpiration to evapotranspiration, and crop transpiration efficiency, which gave rise to greater aboveground dry matter accumulation and more dry matter accumulation in grain. As a result, grain yield under NTS and NTP was significantly increased by 45 and 41 % compare to T, respectively, with corresponding improvements in PUE of 43 and 39 %. Therefore, both NTS and NTP have potential to substantially increase grain yield of spring wheat and PUE. However, for sustainable intensification in the long-run, NTS is the best combination of tillage and soil surface management for spring wheat production on the semi-arid Loess Plateau of China.

Nitrogen (N) application is a basic practice for increasing cereal yield and efficient utilization of N sources is key to sustainable intensification. A meta-analysis was conducted to determine how organic fertilization (i.e., livestock manure) affects yield, yield variability and water use efficiency (WUE) of winter wheat (Triticum aestivum L.) in northern China, and how this is impacted by N management and growing environment. Organic fertilization significantly increased grain yield and WUE by an average of 18 and 20 % compared to without organic fertilizer, respectively, and also reduced spatial and temporal yield variability. Compared to without organic fertilizer, change in grain yield was +24, +28, and −11 % for treatments of synthetic nitrogen fertilizer plus organic fertilizer with the same level of synthetic nitrogen (NOF), decreased level of synthetic nitrogen fertilizer combined with organic fertilizer (NLOF), and a portion of synthetic nitrogen fertilizer replaced with organic nitrogen fertilizer at the same level of nitrogen (NROF), respectively. The positive effect of organic fertilizer on grain yield and WUE of winter wheat was greatest when yield levels was

BACKGROUND This study determined the long-term effect of tillage systems on soil properties and crop yields in a semi-arid environment. Field pea (Pisum sativum L.) and spring wheat (Triticum aestivum L.) were alternately grown in six tillage systems at Dingxi (35° 28′ N, 104° 44′ E), north-west China starting in 2001. RESULTS After the first 6 years of experiments, conventional tillage with stubble incorporating (TS) and no-till with stubble cover (NTS) increased soil organic matter by 9.9% and 13.0%, respectively, compared to the conventional tillage with stubble removed (T); both TS and NTS also increased soil microbial counts, available K and P, and total N. No-till with stubble removed (NT), NTS and NTP (no-till with plastic mulching) had 20.7%, 62.6% and 43.7% greater alkaline phosphatase activity compared to the T treatment. Soil catalase, urease and invertase activities were all greater in the no-till treatments than in the T treatment. Averaged across 6 years, both wheat and pea achieved highest grain yields under NTS treatment. CONCLUSION No-till with stubble retention is the most promising system for improving soil physical, biological and chemical properties, and increasing crop yields, and thus, this system can be adopted in areas with conditions similar to the semi-arid north-west China. © 2015 Society of Chemical Industry