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Straw is widely incorporated into soil worldwide, but most studies have concentrated on the effects of straw mulching or incorporation with topsoil. To determine the effect of depth of straw incorporation on bacterial and fungal communities, we established a field experiment in a region in Northeast China with Haplic Chernozems using four treatments: conventional tillage (CT, tillage to a depth of 15 cm with no straw incorporation), straw incorporation with conventional tillage (SCT, tillage to a depth of 15 cm), inversion tillage (IT, tillage to a depth of 35 cm) and straw incorporation with inversion tillage (SIT, tillage to a depth of 35 cm). The soils were managed by inversion to a depth of 15 or 35 cm after harvest. The results show that soil organic carbon content was significantly higher and pH and bulk density were significantly lower in the 15–35 cm layer in IT and SIT than CT and SCT. Fungal abundance was higher with straw incorporation, but fungal diversity was lower in the 0–15 cm layer in SCT and SIT than in CT and IT. Path length in the bacterial network was shorter and connectivity was higher in CT + SCT than in IT + SIT, leading to a more complex ecosystem, and the fungal network had opposite patterns. The key taxa in the phylum Actinobacteriota and Ascomycota in the microbial networks changed dramatically at the genus level following inversion tillage with straw amendment, which may increase bacterial network resistance to environmental disturbances and unstable fungal networks, resulting in large changes in the fungal community involved in the decomposition of recalcitrant straw-derived C and the more efficient acquisition of limiting resources. [ABSTRACT FROM AUTHOR]

• Soil quality is significantly improved by desert reclamation. • The SOC stocks show exponential change with long-term conventional cultivation. • The N:P ratio has an essential influence on SOC and nutrient stocks. Reclamation in desert-oasis areas is effective for improving land productivity and ensuring food supply. However, the understanding of the sustainable productivity of soils under long-term conventional cultivation after desert reclamation is still poor. This study was conducted to determine soil structural properties, organic carbon stocks (SOCS) and nutrient stocks under four desert reclamation ages (0, 30, 60, and 100) in the arid region of northwest China, and evaluate the influence of long-term conventional cultivation on desert soil quality. The results indicated that soil structural stability index (SI) in topsoil improved after desert reclamation, but showed a slight downward trend after 60 years of cultivation, and farmland soil in the study area was still at serious risk of degradation (SI ≤ 5 %) overall. SOCS were enlarged by 4.2 times after desert reclamation, and nitrogen stocks (NS) and phosphorus stocks (PS) were increased by 1.2–6.5 times. However, the regression analysis showed that SOCS and NS in 0–40 cm soil layer and PS in topsoil stopped increasing after about 60-year conventional cultivation. Soil stoichiometry, pH and texture were the key factors affecting SOCS, NS and PS in oasis farmlands. In summary, our study emphasized that soil quality in arid areas was greatly improved after desert reclamation, however, long-term conventional agriculture management measures limited this improvement. Therefore, long-term conventional management of agricultural land in arid areas should introduce appropriate conservation measures to achieve sustainable soil productivity. [ABSTRACT FROM AUTHOR]

In agroecosystems, straw return is considered an important agricultural management practice influencing soil respiration. However, the impact of straw return on soil respiration is equivocal and the underlying mechanisms underpinning any responses remain unclear. To address this, we synthesized 86 recently published papers on dryland agroecosystems in China, which comprise approximately 74% of the agricultural land area, using a meta-analysis approach and explored the influence of straw return on soil respiration and the underlying mechanisms involved. Straw return resulted in a 13.5% increase in soil respiration, a 9.4% increase in soil moisture, a 10.4% increase in crop yield, a 18.9% increase in SOC (soil organic carbon), and a 2.6% decrease in soil temperature. Compared to conventional tillage without straw return treatment, the increase in soil respiration in response to straw return was closely related to modifications in soil temperature, soil moisture, SOC, and crop yield (P < 0.05). The contribution of the different drivers to increases in soil respiration in response to straw return showed a trend of crop yield > soil temperature > SOC > soil moisture. In addition, straw mulching, crop planting system, tillage method, and fertilization modified the effect of straw return on soil respiration. The increase in soil respiration was less when straw was used as a mulch (12.9%), compared to when it was incorporated into the soil (18.8%). The cropping system also influenced the effect of straw return on soil respiration and was increased by 21.1% in inter-crops, and by 17.3% and 11.0% in monocultures and rotations treatments, respectively. Our results also showed that the effect of straw return on soil respiration was larger in deep tillage treatments than in shallow tillage treatments (26.9% vs.18.7%). In addition, the effect of straw return on soil respiration was also larger in fertilized treatment compared to unfertilized one (12.7% vs. 0.5%). However, this depended on the amount of nitrogen fertilizer applied rates and was higher (14.8%) with low (<300 kg ha−1) application rates compared to high (≧300 kg ha−1) ones (2.5%). Therefore, in dryland agroecosystems in China, biological factors, especially those related to crop yield, may be a more important factor regulating the effect of straw return on soil respiration. However, straw mulching, crop planting system, tillage method, and fertilization can modify the effect of straw return on soil respiration. [ABSTRACT FROM AUTHOR]

Abstract: Soil organic carbon (SOC) is a core indicator of soil quality. A proper tillage system can improve SOC accumulation and benefit land restoration. This improvement is especially significant in loess soil, which is undergoing serious degradation in China. In this study, we chose a field that was used for crop production and used a traditional moldboard plow with crop residue removal (CT) for over 10 years. We then carried out a long‐term field experiment (2007–2015) and changed the tillage system from a moldboard plow with crop residue removal to either a moldboard plow with buried straw system (BT), a no‐tillage with straw mulch system (NT), or a subsoiling with straw mulch system (ST) to evaluate the effect of tillage system change and the effects of tillage systems on SOC storage. Tillage system change influenced SOC content, NT, ST, and BT showed higher values of SOC content and increased 8.34, 7.83, and 1.64 Mg·C·ha−1, respectively, compared with CT. Among the 3 changed tillage systems, NT and ST showed a 12.5% and 11.6% increase in SOC content then BT, respectively. Tillage system change influenced SOC stratification ratio values, with higher value observed in BT and NT compared CT but ST. Therefore, in loess soil, changing tillage system can significantly improve SOC storage and change profile distribution. The NT and ST treatments showed a more marked SOC increase, but the increase value in stratification ratio with NT still needs attention, and our results is meaningful for soil quality improvement and land restoration. [ABSTRACT FROM AUTHOR]

Conventional tillage refers to the tillage process, especially the spring and autumn plowing process in which all the soil surface layer is disturbed, generally tilling approximately 20 cm deep. Conventional tillage is still widely used in sloping land, which leads to serious soil erosion and land degradation. The effect of tillage on soil erosion is defined by Tillage factor (T) in the model. The purpose of this study is to analyze the effect of conventional tillage on soil erosion and to calculate the value of the conventional tillage Factor T. The values of the conventional tillage factor (T value) were calculated for different soil and water conservation zones in China by collecting published literature and plot measurements from unpublished monitoring sites. The results showed that (1) the tillage factors of conventional tillage in China ranged from 0.27 to 0.55, with the largest being the North earth-stony region, the smallest being the Qinghai-Tibet plateau region, and the other six regions, namely, the Northeastern mollisol, the Northern wind erosion, the Northwest Loess Plateau, the South red soil, the Southwestern purple soil and the Southwestern karst region, were 0.34, 0.28, 0.53, 0.37, 0.35 and 0.29, respectively. In the regional soil erosion evaluation, the values can be taken by each of the eight main erosion type regions. (2) In the water erosion area except for the northeast, there is an obvious north south difference in the distribution of the T value, showing a decreasing trend from north to south. In practical use, the T value of the corresponding latitude area can be determined according to the Equation T = 0.2351φ- 0.02225, where φ is the latitude (°). (3) The T values of contour tillage, no-till, and monopoly tillage measures are significantly lower than the T values of conventional tillage, which have significant soil and water conservation benefits. The study initially determined the conventional tillage T values for each water conservation subzone, which can provide basic parameters for soil loss prediction on sloping land. • The t values of 8 subzones are calculated, which can be used in the actual survey. • A formula for calculating t-values is proposed, which can be used for unmeasured areas. • Conventional tillage can reduce soil loss and must be assigned a reasonable value. [ABSTRACT FROM AUTHOR]

Knowledge about the changes in soil nitrogen pools under different tillage managements is necessary to assess the feasibility of adoption of conservation practices for sustaining productivity and protecting the environment in dryland farming in northern China. We investigated the long-term effects (22 years) of no-till with residue retention (NTR) on total soil N and its fractions in a dry-land winter wheat ( Triticum aestivum L.) cropping system in northern China. Compared with conventional tillage without residue retention (CT), significantly higher soil total N (STN) concentrations were observed in the surface soil layer (0–10 cm) under NTR. Meanwhile, more soil N accumulated for the whole soil profile (0 to 60 cm) in the NTR (3.38 Mg ha − 1 ) treatment relative to the CT (3.17 Mg ha − 1 ) treatment. The particulate organic matter N (PON), microbial biomass N (MBN), and water extractable organic N (WEON) levels in the NTR treatments were 52.3%, 116%, and 69.4% greater at a depth of 0–5 cm and 41.6%, 108%, and 44.9% greater at a depth of 5–10 cm, respectively, compared with the CT treatment. However, no differences were observed below the 10 cm layer. At a depth of 0–60 cm, the soil NH 4 -N content under CT was higher than that under NTR. However, the soil NO 3 -N contents in the NTR treatments were significantly greater at a depth of 0–10 cm and were not significantly different at a depth of 10–60 cm, relative to the CT treatment. Significantly positive correlations were observed between the STN and the labile organic N fractions. Overall, the results show that no-till coupled with residue retention is an effective management method for improving soil N stocks and increasing soil fertility. Nonetheless, other benefits associated with NT and residue retention present greater challenges regarding their popularization and application in the dryland farming areas in northern China. [ABSTRACT FROM AUTHOR]

Abstract: The influence of different tillage practices on soil organic carbon levels is more significant under long-term tillage compared to short-term tillage. Despite the great interest in the effect of no-tillage (NT) management practice on carbon sequestration, the long-term effect of NT practice on soil organic carbon and its fractions in northern China remain unclear. We evaluated the long-term effects (after 17years) of NT and conventional tillage (CT) practices on soil organic carbon and its fractions at different depths ranging from 0 to 60cm using a cinnamon soil in Shanxi, China. A randomised block design with three replications was used to evaluate both the tillage and its effects on the yield performance of winter wheat (Triticum aestivum L.). After 17years, the soil organic carbon (SOC) concentration in the NT soil was greater than that of the CT soil, but only in the layer that was located between 0 and 10cm. There was a significant accumulation of SOC (0–60cm) in the NT soil (50.2MgCha−1) compared to that observed in the CT soil (46.3MgCha−1). The particulate organic matter C (POM-C), dissolved organic C (DOC), and microbial biomass C (MBC) levels in the 0–5cm layer under NT treatment were 155%, 232%, and 63% greater, respectively, compared to the CT treatment. The POM-C, DOC, and MBC in the 5–10cm layer under NT treatment were 67%, 123%, and 63% greater, respectively, compared to the CT treatment. Below 10cm, the labile carbon observed in the NT treatment did not differ from that of the CT treatment. Significantly positive correlations were observed between the SOC and the labile organic C fractions. Moreover, the winter wheat (T. aestivum L.) yield increased 28.9% in the NT treatment compared to the CT treatment. The data show that NT is an effective and sustainable management practice that improves carbon sequestration and increases soil fertility, resulting in higher winter wheat yields in the rainfed dryland farming areas of northern China. [Copyright &y& Elsevier]

Modelling of the carbon dynamics in arable soils is complex and the accuracy of the predictions is unknown before the model is applied to each specific site. Objectives were (i) to test the accuracy of predictions of the carbon dynamics using the Rothamsted Carbon (RothC) Model in a field trial in Quzhou, North China Plain, using different methods for initialization and estimation of carbon input into the soil and (ii) to test the applicability of the RothC model for plots with either conventional tillage (CT) or no-tillage (NT) systems. A field trial was conducted with applications of differing amounts of N (0, 112 or 187 kg N ha−1 year−1), P (0, 75 or 150 kg P2O5 ha−1 year−1) and wheat straw (0, 2.25 or 4.5 t DM ha−1 year−1) in differing combinations with either CT or NT for 18 years. CT and NT affected stocks of soil organic carbon (SOC) similarly. Carbon inputs from crops were either estimated from published regression functions that relate C inputs to crop yield including rhizodeposition (models 1 and 2) or published root:aboveground biomass ratios (model 3). Model 1, which was not calibrated to the site conditions, was successful in predicting the carbon dynamics in seven out of nine treatments (model efficiencies EF ranged from 0.28 to 0.87), whereas for two treatments, EF (−0.35 and−2.3) indicated an unsuccessful prediction. The prediction of the C dynamics in NT experiments using model 1 was generally successful, but this may have been due to the fact that NT did not have a specific effect on SOC stocks for this trial. Model 2, which was the same as model 1 except for an optimization of the stock of inert organic matter using one treatment, predicted SOC stocks in the remaining eight treatments overall better than model 1. Model 3 was less successful than models 1 and 2 in all treatments (−19 ≤ EF ≤ 0.56). The results indicate that the RothC model may successfully predict C dynamics—for the site studied even without prior calibration as in model 1—, but care should be taken in choosing an appropriate approach for estimating C inputs into the soil. [ABSTRACT FROM AUTHOR]

Abstract: Agricultural tillage practices play an important role in the production and/or consumption of green house gas (GHG) that contributes substantially to the observed global warming. Central China is one of the world''s major rice producing areas but a few studies have tried to characterize the mechanisms of GHG release from rice paddy field and quantify global warming (GWPs) based on GHGs emission on this region. In this study four tillage systems consisting of no-tillage with no fertilizer (NT0), conventional tillage with no fertilizer (CT0), no-tillage with compound fertilizer (NTC) and conventional tillage with compound fertilizer (CTC) applications in rice (Oryza sativa L.) cultivation were compared in terms of the carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions from different tillage systems of the subtropical region of China during the rice growing season in 2008. GWPs based on CO2, CH4 and N2O''s cumulative emissions were also compared. Tillage and fertilization had no influence on CO2 emissions. No-tillage had no effect on N2O emissions but significantly affected CH4 emissions. Application of fertilizer significantly affected CH4 and N2O emissions. Higher CH4 emissions and lower N2O emissions were observed in CTC than in NTC. Cumulative CH4 emission flux in NTC was 51.68gCH4 m−2 while it was 65.96gCH4 m−2 in CTC, 28% (p <0.05) higher than that in NTC. Cumulative N2O emission flux in CTC was 561.00mgN2Om−2, and was 741.71mgN2Om−2 in NTC, 33% (p <0.05) higher than that in CTC. There was no significant difference in N2O emissions between NT0 and CT0 systems, but significant in CH4 emissions. GWP of CTC was 26011.58kgCO2 ha−1, which was 12% higher than that in NTC (23361.3kgCO2 ha−1), therefore our findings show that no-tillage system was an effective strategy to reduce GWP from rice paddies in central China and thus can serve as a good agricultural system for environmental conservation. [Copyright &y& Elsevier]

Abstract: Field rainfall simulations were conducted in 2002 and 2005 to study the effects of different soil management practices on the total phosphorous (TP) and Olsen-P losses by soil erosion and redistribution along a 15 m long slope in Luoyang, Henan province, China. Field plots were set up in 2001 and included the following soil management practices: subsoiling with mulch (SSM), no-till with mulch (NTM), reduced tillage (RT), and a conventional tillage control (CT). The results showed that there were no significant differences in TP and Olsen-P content in the sediment load between different plots after 6 years uniform tillage practices. The enrichment of TP and Olsen-P at the lower slope showed a clear redistribution along the slope. Effects of tillage practices on the temporal pattern of the enrichment ratio (ER) of TP and Olsen-P was not uniform. ERTP values were initially high and diminished after a short period of time and leveled to the end of the rainfall test in CT and RT plots, but remained ≥1. The ER of Olsen-P at the end of rainfall simulation showed a significant difference when compared to the initial stage, 0.78 to 1.60, respectively. However, the temporal loss rate of TP and Olsen-P showed a similar pattern because it was more depending on the sediment loss rate than on the concentration in the sediment. SSM resulted in 96% less TP and Olsen-P erosion loss compared to CT in 2002. Also, SSM showed the highest reduction in TP and Olsen-P loss after 4 years consistent practice. RT reduced TP and Olsen-P loss by 30%, although the runoff reduction was not significant. NTM was the best alternative with respect to TP and Olsen-P conservation, when considering its lower operational costs. [Copyright &y& Elsevier]

Abstract: The effects of middle term (7 years) consistent tillage practices on the catalase (CAT), urease (URE) and invertase (INV) activities were investigated during the whole winter wheat growing period on a loess soil in Luoyang (east edge of the Chinese Loess Plateau, Henan province, China). Field plots, set up in 1999, included following tillage practices: subsoiling with mulch (SS), no-till with mulch (NT), reduced tillage (RT), and a conventional control (CT). A clear redistribution of soil organic carbon (SOC) and total nitrogen (TN) was found along the slope in RT and CT, however, no difference was observed between studied enzyme activities along different slope positions. SS had higher winter wheat yield than other treatments, which was attributed to the increased soil water content and improvement of soil fertility. Changes in soil temperature and soil moisture content influenced the magnitude of the enzyme activities, but not the ranking of the different treatments during most of the season. SS consistently had higher enzyme activities compared to other treatments. This indicated that seasonal fluctuations did not obscure effects associated with soil tillage practices and enzyme activities could reflect the effects of conversion of soil tillage practices on soil quality. Time within the growing season had a clear impact upon the enzyme activities. Comparatively higher enzyme activities were observed in the stages with vigorous vegetative growth of winter wheat than in stages with productive growth. [Copyright &y& Elsevier]

The spatial and temporal variability of soil CO 2 emissions from agricultural soils is inherently high. While tillage and crop residue practices play vital roles in governing soil CO 2 emission, their effects on the variability of soil CO 2 fluxes across depths and seasons are still poorly understood. To address this, an experiment consisting of four treatments, namely conventional tillage with (CT+) and without crop residue application (CT-), as well as no tillage with (NT+) and without crop residue application (NT-), was conducted to investigate soil CO 2 fluxes at top 40 cm soils with 10-cm depth intervals in a winter wheat-summer maize rotation system in the North China Plain. Our results showed soil CO 2 fluxes increased with depth in both the wheat- and maize-growing seasons. However, the dominant factors in regulating soil CO 2 fluxes changed with soil depth and seasons. In the wheat-growing season, increase in soil CO 2 fluxes with depth was attributed to the increase of dissolved organic carbon-to-nitrogen ratio (DOC/DON) and a decline in soil DON concentration along the soil profile. These factors explained about 55-96% of the total variation in soil CO 2 fluxes at different soil depths. In the maize-growing season, the dominant factors were soil DOC/DON ratio, soil DON concentrations, and soil moisture. These factors explained approximately 79-96% of the total variation in soil CO 2 fluxes along the soil depth. Greater soil CO 2 fluxes (except at 30-40 cm depth) were observed in NT- than CT- treatments. Furthermore, crop residue application enhanced soil CO 2 fluxes across different depths, but the enhancement was more prominent in CT+ than NT+. Moreover, soil CO 2 fluxes in the maize-growing season were greater than those in the wheat-growing season. Our results demonstrate that the effects of tillage regimes and crop residue management practices on soil CO 2 emissions are not confined only to the plough layer but can extend to soils of over 30 cm depths. We also need to revisit the general conventional view that no tillage can significantly reduce soil CO 2 emissions compared with conventional tillage for better climate change mitigation.

Previous research has shown the varied effect of earthworms on soil carbon dynamics. We carried out a 180-day incubation experiment with earthworms and maize residue additions under conventional tillage (CT) and no tillage (NT) system conditions to quantify the earthworm effect in the black soil of northeastern China. Earthworms did not affect soil CO 2 emissions, while residue addition significantly increased such emissions. The effects of earthworms on dissolved organic carbon (DOC) and microbial biomass carbon (MBC) gradually weakened with time in CT with and without residue addition, but gradually increased with time in NT with residue addition. In the CT system, earthworms accelerated the soil organic carbon (SOC) mineralization; and the newly added residue decomposed into SOC. In the NT system, earthworms accelerated the decomposition of native residues increasing the SOC content; this increase in decomposition rates by earthworms was greater than the inhibitory effect imposed by the addition of the new residue. Earthworms and residues combine to play a single role in CT and NT. This result will help in the understanding of the role of earthworms and residue in SOC dynamics, and in the development of management strategies to improve SOC.