Combining No-Tillage with Hairy Vetch Return Improves Production and Nitrogen Utilization in Silage Maize.

The combination of no-till farming and green manure is key to nourishing the soil and increasing crop yields. However, it remains unclear how to enhance the efficiency of green manure under no-till conditions. We conducted a two-factor field trial of silage maize rotated with hairy vetch to test the effects of tillage methods and returning. Factor 1 is the type of tillage, which is divided into conventional ploughing and no-tillage; factor 2 is the different ways of returning hairy vetch as green manure, which were also compared: no return (NM), stubble return (H), mulching (HM), turnover (HR, for CT only), and live coverage (LM, for NT only). Our findings indicate that different methods of returning hairy vetch to the field will improve maize yield and quality. The best results were obtained in CT and NT in HM and LM, respectively. Specifically, HM resulted in the highest dry matter quality and yield, with improvements of 35.4% and 31.9% over NM under CT, respectively. It also demonstrated the best economic and net energy performance. However, other treatments had no significant effect on the beneficial utilization and return of nutrients. The LM improved yields under NT by boosting soil enzyme activity, promoting nitrogen transformation and accumulation, and increasing nitrogen use efficiency for better kernel development. Overall, NTLM is best at utilizing and distributing soil nutrients and increasing silage maize yield. This finding supports the eco-efficient cultivation approach in silage maize production in the region.

Dynamic responses of soil microbial communities to seasonal freeze-thaw cycles in a temperate agroecosystem.

Soil freeze-thaw cycles (FTCs) are common in temperate agricultural ecosystems during the non-growing season and are progressively influenced by climate change. The impact of these cycles on soil microbial communities, crucial for ecosystem functioning, varies under different agricultural management practices. Here, we investigated the dynamic changes in soil microbial communities in a Mollisol during seasonal FTCs and examined the effects of stover mulching and nitrogen fertilization. We revealed distinct responses between bacterial and fungal communities. The dominant bacterial phyla reacted differently to FTCs: for example, Proteobacteria responded opportunistically, Actinobacteria, Acidobacteria, Choroflexi and Gemmatimonadetes responded sensitively, and Saccharibacteria exhibited a tolerance response. In contrast, the fungal community composition remained relatively stable during FTCs, except for a decline in Glomeromycota. Certain bacterial OTUs acted as sensitive indicators of FTCs, forming keystone modules in the network that are closely linked to soil carbon, nitrogen content and potential functions. Additionally, neither stover mulching nor nitrogen fertilization significantly influenced microbial richness, diversity and potential functions. However, over time, more indicator species specific to these agricultural practices began to emerge within the networks and gradually occupied the central positions. Furthermore, our findings suggest that farming practices, by introducing keystone microbes and changing interspecies interactions (even without changing microbial richness and diversity), can enhance microbial community stability against FTC disturbances. Specifically, higher nitrogen input with stover removal promotes fungal stability during soil freezing, while lower nitrogen levels increase bacterial stability during soil thawing. Considering the fungal tolerance to FTCs, we recommend reducing nitrogen input for manipulating bacterial interactions, thereby enhancing overall microbial resilience to seasonal FTCs. In summary, our research reveals that microbial responses to seasonal FTCs are reshaped through land management to support ecosystem functions under environmental stress amid climate change.

Microbial necromass contribution to soil carbon storage via community assembly processes.

Soil organic matter has been well acknowledged as a natural solution to mitigate climate change and to maintain agricultural productivity. Microbial necromass is an important contributor to soil organic carbon (SOC) storage, and serves as a resource pool for microbial utilization. The trade-off between microbial births/deaths and resource acquisition might influence the fate of microbial necromass in the SOC pool, which remains poorly understood. We coupled soil microbial assembly with microbial necromass contribution to SOC on a long-term, no-till (NT) farm that received maize (Zea mays L.) stover mulching in amounts of 0 %, 33 %, 67 %, and 100 % for 8 y. We characterized soil microbial assembly using the Infer Community Assembly Mechanisms by Phylogenetic-bin-based null model (iCAMP), and microbial necromass using its biomarker amino sugars. We found that 100 % maize stover mulching (NT100) was associated with significantly lower amino sugars (66.4 mg g-1 SOC) than the other treatments (>70 mg g-1 SOC). Bacterial and fungal communities responded divergently to maize stover mulching: bacterial communities were positive for phylogenetic diversity, while fungal communities were positive for taxonomic richness. Soil bacterial communities influenced microbial necromass contribution to SOC through determinism on certain phylogenetic groups and bacterial bin composition, while fungal communities impacted SOC accumulation through taxonomic richness, which is enhanced by the positive contribution of dispersal limitation-dominated saprotrophic guilds. The prevalence of homogeneous selection and dispersal limitation on microbial cell wall-degrading bacteria, specifically Chitinophagaceae, along with increased soil fungal richness and interactions, might induce the decreased microbial necromass contribution to SOC under NT100. Our findings shed new light on the role of microbial assembly in shaping the dynamics of microbial necromass and SOC storage. This advances our understanding of the biological mechanisms that underpin microbial necromass associated with SOC storage, with implications for sustainable agriculture and mitigation of climate change.

Monitoring the Spatial Distribution of Cover Crops and Tillage Practices Using Machine Learning and Environmental Drivers across Eastern South Dakota.

The adoption of conservation agriculture methods, such as conservation tillage and cover cropping, is a viable alternative to conventional farming practices for improving soil health and reducing soil carbon losses. Despite their significance in mitigating climate change, there are very few studies that have assessed the overall spatial distribution of cover crops and tillage practices based on the farm's pedoclimatic and topographic characteristics. Hence, the primary objective of this study was to use multiple satellite-derived indices and environmental drivers to infer the level of tillage intensity and identify the presence of cover crops in eastern South Dakota (SD). We used a machine learning classifier trained with in situ field samples and environmental drivers acquired from different remote sensing datasets for 2022 and 2023 to map the conservation agriculture practices. Our classification accuracies (>80%) indicate that the employed satellite spectral indices and environmental variables could successfully detect the presence of cover crops and the tillage intensity in the study region. Our analysis revealed that 4% of the corn (Zea mays) and soybean (Glycine max) fields in eastern SD had a cover crop during either the fall of 2022 or the spring of 2023. We also found that environmental factors, specifically seasonal precipitation, growing degree days, and surface texture, significantly impacted the use of conservation practices. The methods developed through this research may provide a viable means for tracking and documenting farmers' agricultural management techniques. Our study contributes to developing a measurement, reporting, and verification (MRV) solution that could help used to monitor various climate-smart agricultural practices.

Impact of crop rotation and tillage operations on mitigating greenhouse gas emissions and evaluation of sustainability index in rice- wheat-green gram cropping system of north Bihar.

In North Bihar (NB), the conventional rice-wheat cropping system has led to soil, water, and environmental degradation, alongside low profitability, threatening sustainability. To address these concerns, a thorough field research was conducted over the course of three years to assess different methods of tillage and crop establishment in a rice, wheat, and greengram cycle. The experiment involved five scenarios with different combinations of crop rotation, tillage techniques, seeding procedures, fertilizer use, and irrigation strategies. Uncertainty analysis showed no significant change in mean and variance estimation among seven scenario replications at 5% significance level. Compared to traditional farming (SN-1), managing DSR-rice (SN-5) increased profitability by 17.56%, improved energy use efficiency (EUE) by 32.16%, and reduced irrigation by 24.76% and global warming potential (GWP) by 23.46%. Similarly, substituting zero tillage wheat (ZTW) SN-5 resulted in comparable profitability gains (18.25%) and significant improvements in irrigation (10 %), EUE (+48.65%), and GWP (-20 %) compared to SN-1. Green gram ZT also showed increased profitability (17.35%), with notable improvements in EUE (+38.31%) and GWP (-12.92%) compared to SN-1. Principal component and correlation analyses revealed relationships between total energy inputs, yields, economic returns, and sustainability indices, highlighting the benefits of crop rotation and tillage practices in optimizing resource use. The study suggests that compared to conventional systems, significant improvements in productivity, profitability, energy-use efficiency, and environmental mitigation can be achieved with Crop Rotation and Tillage Operations techniques.

Greenhouse gas emissions from the growing season are regulated by precipitation events in conservation tillage farmland ecosystems of Northeast China.

Reducing greenhouse gas (GHG) emissions from agricultural ecosystems is vital to mitigate global warming. Conservation tillage is widely used in farmland management to improve soil quality; however, its effects on soil GHG emissions remain poorly understood, particularly in high-yield areas. Therefore, our study aimed to evaluate the effects of no-tillage (NT) combined with four straw-mulching levels (0 %, 33 %, 67 %, and 100 %) on GHG emission risk and the main influencing factors. We conducted in-situ observations of GHG emissions from soils under different management practices during the maize-growing season in Northeastern China. The results showed that NT0 (705.94 g m-2) reduced CO2 emissions by 18 % compared to ridge tillage (RT, 837.04 g m-2). Different straw mulching levels stimulated N2O emissions after rainfall, particularly under NT combined with 100 % straw mulching (2.89 kg ha-1), which was 45 % higher than that in any other treatments. The CH4 emissions flux among different treatments was nearly zero. Overall, straw mulching levels had no significant effect on the GHG emissions. During the growing season, soil NH4+-N (< 20 mg kg-1) remained low and decreased with the extension of growth stage, whereas soil NO3--N initially increased and then decreased. More importantly, the results of structural equation modeling indicate that: a) organic material input and soil moisture are key factors affecting CO2 emissions, b) nitrogen fertilizer and soil moisture promote N2O emissions, and c) climatic factors exert an inexorable influence on the GHG emissions process. Our conclusions emphasize the necessity of incorporating precipitation-response measures into farmland management to reduce the risk of GHG emissions.

Conservation tillage facilitates the accumulation of soil organic carbon fractions by affecting the microbial community in an eolian sandy soil.

Conservation tillage (CT) is an important agronomic measure that facilitates soil organic carbon (SOC) accumulation by reducing soil disturbance and plant residue mulching, thus increasing crop yields, improving soil fertility and achieving C neutrality. However, our understanding of the microbial mechanism underlying SOC fraction accumulation under different tillage practices is still lacking. Here, a 6-year in situ field experiment was carried out to explore the effects of CT and traditional tillage (CK) practices on SOC fractions in an eolian sandy soil. Compared with CK, CT increased the particulate OC (POC) content in the 0-30 cm soil layer and the mineral-associated OC (MAOC) content in the 0-20 cm soil layer. Moreover, tillage type and soil depth had significant influences on the bacterial, fungal and protistan community compositions and structures. The co-occurrence network was divided into 4 ecological modules, and module 1 exhibited significant correlations with the POC and MOC contents. After determining their topological roles, we identified the keystone taxa in the network. The results indicated that the most common bacterial taxa may result in SOC loss due to low C use efficiency, while specific fungal (Cephalotrichum) and protistan (Cercozoa) species could facilitate SOC fraction accumulation by promoting macroaggregate formation and predation. Therefore, the increase in keystone fungi and protists, as well as the reduction in bacteria, drove module 1 community function, which in turn promoted SOC sequestration under CT. These results strengthen our understanding of microbial functions in the accrual of SOC fractions, which contributes to the development of conservation agriculture on the Northeast China Plain.

Conservation tillage: a way to improve yield and soil properties and decrease global warming potential in spring wheat agroecosystems.

Climate change is one of the main challenges, and it poses a tough challenge to the agriculture industry globally. Additionally, greenhouse gas (GHG) emissions are the main contributor to climate change; however, croplands are a prominent source of GHG emissions. Yet this complex challenge can be mitigated through climate-smart agricultural practices. Conservation tillage is commonly known to preserve soil and mitigate environmental change by reducing GHG emissions. Nonetheless, there is still a paucity of information on the influences of conservation tillage on wheat yield, soil properties, and GHG flux, particularly in the semi-arid Dingxi belt. Hence, in order to fill this gap, different tillage systems, namely conventional tillage (CT) control, straw incorporation with conventional tillage (CTS), no-tillage (NT), and stubble return with no-tillage (NTS), were laid at Dingxi, Gansu province of China, under a randomized complete block design with three replications to examine their impacts on yield, soil properties, and GHG fluxes. Results depicted that different conservative tillage systems (CTS, NTS, and NT) significantly (p < 0.05) increased the plant height, number of spikes per plant, seed number per meter square, root yield, aboveground biomass yield, thousand-grain weight, grain yield, and dry matter yield compared with CT. Moreover, these conservation tillage systems notably improved the soil properties (soil gravimetric water content, water-filled pore space, water storage, porosity, aggregates, saturated hydraulic conductivity, organic carbon, light fraction organic carbon, carbon storage, microbial biomass carbon, total nitrogen, available nitrogen storage, microbial biomass nitrogen, total phosphorous, available phosphorous, total potassium, available potassium, microbial counts, urease, alkaline phosphatase, invertase, cellulase, and catalase) while decreasing the soil temperature and bulk density over CT. However, CTS, NTS, and NT had non-significant effects on ECe, pH, and stoichiometric properties (C:N ratio, C:P ratio, and N:P ratio). Additionally, conservation-based tillage regimes NTS, NT, and CTS significantly (p < 0.05) reduced the emission and net global warming potential of greenhouse gases (carbon dioxide, methane, and nitrous oxide) by 23.44, 19.57, and 16.54%, respectively, and decreased the greenhouse gas intensity by 23.20, 29.96, and 18.72%, respectively, over CT. We conclude that NTS is the best approach to increasing yield, soil and water conservation, resilience, and mitigation of agroecosystem capacity.

Drought effects on trait space of winter wheat are independent of land management.

Investigating plant responses to climate change is key to develop suitable adaptation strategies. However, whether changes in land management can alleviate increasing drought threats to crops in the future is still unclear. We conducted a management × drought experiment with winter wheat (Triticum aestivum L.) to study plant water and vegetative traits in response to drought and management (conventional vs organic farming, with intensive vs conservation tillage). Water traits (root water uptake pattern, stem metaxylem area, leaf water potential, stomatal conductance) and vegetative traits (plant height, leaf area, leaf Chl content) were considered simultaneously to characterise the variability of multiple traits in a trait space, using principal component analysis. Management could not alleviate the drought impacts on plant water traits as it mainly affected vegetative traits, with yields ultimately being affected by both management and drought. Trait spaces were clearly separated between organic and conventional management as well as between drought and control conditions. Moreover, changes in trait space triggered by management and drought were independent from each other. Neither organic management nor conservation tillage eased drought impacts on winter wheat. Thus, our study raised concerns about the effectiveness of these management options as adaptation strategies to climate change.

Effects of long-term no-tillage and different stover mulching amounts on soil carbon and nitrogen contents and enzyme activities of carbon and nitrogen cycle in Mollisols.

To understand the effects of different stover mulching amounts in no-tillage on soil carbon and nitrogen contents and enzyme activities, finding a stover mulching amount which can meet the requirement of soil carbon and nitrogen accumulation while maximizing economic benefits, we conducted a long-term conservation tillage field experiment since 2007 in Mollisols area of Northeast China. We analyzed soil carbon and nitrogen contents, enzyme activities and economic benefits under conventional tillage (Control, CT), no-tillage without stover mulching (NT0), no-tillage with 33% stover mulching (NT33), no-tillage with 67% stover mulching (NT67), and no-tillage with 100% stover mulching (NT100) before planting in May 2020. The results showed that compared with CT, NT0 did not affect soil organic carbon (SOC) and total nitrogen (TN) contents, but increased soil organic carbon recalcitrance and decreased the availability of dissolved organic nitrogen (DON) and ammonium nitrogen. Compared with NT0, no-tillage with stover mulching significantly increased SOC contents in 0-10 cm layer and increased with the amounts of stover. In addition, NT67 and NT100 significantly increased SOC stocks, facilitating the accumulation of soil organic matter. The effects of different stover mulching amounts on soil nitrogen content in 0-10 cm layer were different. Specifically, NT33 increased DON content and DON/TN, NT67 increased DON content, while NT100 increased TN content. Compared with CT, NT0 decreased peroxidase (POD) activity in 0-10 cm layer. Compared with NT0, NT33 increased ß-glucosidase (ßG), cellobiase (CB), 1,4-ß-N-acetylglucosaminidase (NAG), polyphenol oxidase (PPO) and POD activities, while NT67 only increased CB, NAG and POD activities in 0-10 cm soil layer, both alleviated microbial nutrient limitation. NT100 increased PPO activity in 10-20 cm layer. NT33 increased carbon conversion efficiency of stover compared with NT100, and had the highest economic benefit. In all, no-tillage with 33% stover mulching was the optimal strategy, which could promote nutrient circulation, boost stover utilization efficiency, improve the quality of Mollisols, and maximize guaranteed income.

Changes in the degree of lateral root trait plasticity and trade-offs of maize under long-term no tillage.

Introduction: While no tillage (NT) can significantly influence soil structure stratification compared to conventional tillage (CT), a comprehensive understanding of the degree of root trait plasticity and trade-offs of lateral roots of crops at various growth stages along a deep soil profile in response to NT remains elusive. This knowledge gap is important for understanding soil resource acquisition strategies and yield of crops. Methods: We systematically investigated the traits of lateral roots at jointing and flowering stages in a long-term (12 years) experiment in Northeast China where maize (Zea mays) has been continuously planted under CT and NT with or without maize residue mulch on soil surface. We also measured soil penetration resistance and bulk density. Results: Soil penetration resistance was reduced at the jointing stage, and was increased at the flowering stage under NT especially at a depth of 10 - 40 cm. Root length density decreased under NT across the two growth stages by on average 22%. In contrast, specific root length and diameter showed greater plasticity, ranging from -14% to 20% and from -11% to 8%, respectively, relative to those under CT. Discussion: These responses could be attributed to changes in root length proportions with different diameters associated with differences in soil penetration resistance between tillage practices. The negative relationships between root traits were stronger under CT than NT, and became weaker from the jointing stage to the flowering stage. To the best of our knowledge, for the first time, our study provides empirical evidence for pivotal root trait plasticity and trade-offs across growth stages as key indicators of changes in soil structure and resources in response to NT. These insights contribute to a better understanding of soil resource acquisition strategies of crops under NT.

Management of soil cover and tillage regimes in upland rice-sweet corn systems for better system performance, energy use and carbon footprints.

This study investigates the effects of tillage and mulching regimes on rice-sweet corn systems in the lower Gangetic plains, focusing on region-specific and crop-specific impacts on soil-crop-environmental parameters. The experiment consisted of three levels of tillage: conventional (CT), minimum (MT), and zero (ZT), and four levels of mulching: live, leaf litter, paddy straw, and no mulching. The results show that ZT tillage resulted in higher bulk density (BD) compared to other treatments, despite an increase in soil organic carbon (SOC). Live and leaf litter mulching led to slight reductions in BD in the upper soil layers. CT resulted in net depletion of SOC whereas ZT registered a positive sequestration rate of 1.19 Mg ha-1 yr-1. Live and leaf litter mulching increased SOC sequestration by 42.6% and 38.8% compared to paddy straw mulching, respectively. Initially, ZT resulted in a 10.3% reduction in system productivity compared to CT, while MT yields were comparable to CT. However, mulching regimes consistently improved production by 16.4%-25.2% as compared to no mulch. ZT and MT were found to be more affordable than CT, with cost savings of 18.2% and 6.8%, respectively. ZT had the highest B: C ratio, indicating better economic efficiency. Among the mulching treatments, live mulching was the most economical. Both ZT and MT saved input energy by approximately 22.9% and 13.5%, respectively compared to CT. Live mulching resulted in the highest net energy and energy output. Compared to CT, ZT reduced carbon footprint (CF) by 41.5 and 22.2% in rice and sweet corn, respectively. MT scored midway between ZT and CT in all parameters. CT exhibited several limitations, including high input energy requirements, high cost of cultivation, poor economic efficiency, negative environmental impacts, and loss of SOC. ZT initially experienced yield reduction and lower net returns in the early years. Therefore, MT was identified as the best alternative in the initial years before transitioning completely to ZT, as it provided comparable yields to CT with better overall benefits. Among the soil cover regimes, live mulching was found to be the most favorable option across all dimensions.

Long-term conservation tillage enhances microbial carbon use efficiency by altering multitrophic interactions in soil.

Microbial carbon (C) use efficiency (CUE) plays a key role in soil C storage. The predation of protists on bacteria and fungi has potential impacts on the global C cycle. However, under conservation tillage conditions, the effects of multitrophic interactions on soil microbial CUE are still unclear. Here, we investigate the multitrophic network (especially the keystone ecological cluster) and its regulation of soil microbial CUE and soil organic C (SOC) under different long-term (15-year) tillage practices. We found that conservation tillage (CT) significantly enhanced microbial CUE, turnover, and SOC (P < 0.05) compared to traditional tillage (control, CK). At the same time, tillage practice and soil depth had significant effects on the structure of fungal and protistan communities. Furthermore, the soil biodiversity of the keystone cluster was positively correlated with the microbial physiological traits (CUE, microbial growth rate (MGR), microbial respiration rate (Rs), microbial turnover) and SOC (P < 0.05). Protistan richness played the strongest role in directly shaping the keystone cluster. Compared with CK, CT generally enhanced the correlation between microbial communities and microbial physiological characteristics and SOC. Overall, our results illustrate that the top-down control (the organisms at higher trophic levels affect the organisms at lower trophic levels) of protists in the soil micro-food web plays an important role in improving microbial CUE under conservation tillage. Our findings provide a theoretical basis for promoting the application of protists in targeted microbial engineering and contribute to the promotion of conservation agriculture and the improvement of soil C sequestration potential.

[Effects of Conservation Tillage on Herbicide Residues in Maize Field Soil].

It is well known that conservation tillage can improve soil quality, such as soil organic matters. However, limited information on the conservation tillage impacts on pesticides has been reported, which is important to food security. To explore the specific effects of conservation tillage on herbicide residues in soils, parallel soil samples from seven sites under traditional tillage and conservation tillage were collected, respectively, in Jilin Province, Northeast China. The soil properties and characteristics of three herbicides(acetochlor, atrazine, and MCPA-Na) were measured. The results showed that conservation tillage significantly increased total organic carbon(TOC) content, soil water content, and the average particle size of soil aggregates[(2.1±0.1)%, (19.1±1.2)%, and (82.2±3.0) µm increased to(2.9±0.3)%, (22.3±1.5)%, and (97.2±4.2) µm, respectively]. The results also showed that different herbicides were correlated with different soil properties. For example, TOC content and soil water content were positively correlated with atrazine, whereas micro-aggregate content was negatively correlated with acetochlor. Therefore, the effects of conservation tillage on the three herbicide residues were different. For instance, conservation tillage significantly increased the residual amount of atrazine[from(3.8±0.3) ng·g-1 to (17.7±3.0) ng·g-1] in the Dongfeng site by increasing TOC content, whereas it significantly reduced the residual amount of acetochlor[from (50.6±10.3) ng·g-1 to (9.2±2.5) ng·g-1] in the Dehui site by increasing the average particle size of soil aggregates. Generally, this study suggests conservation tillage indeed affected herbicide residues in soils by affecting soil properties. However, the influence of conservation tillage on herbicide residue was dependent on the types of herbicides due to the complex effects of different soil properties on herbicide migration and degradation.

Influencing factors and spatiotemporal heterogeneity of net carbon sink of conservation tillage: evidence from China.

Conservation tillage is an important reform of traditional tillage, which has significant carbon sequestration and emission reduction effects. It is important to investigate the influencing factors and spatiotemporal heterogeneity of net carbon sink of conservation tillage for realizing the "dual carbon" target, and facilitating agricultural sustainable development. This study used the coefficient accounting method to calculate the carbon sink and carbon emission of conservation tillage in China from 2000 to 2019, respectively. Based on this, the net carbon sink of conservation tillage was measured. Then, the spatiotemporal heterogeneity of influencing factors on net carbon sink of conservation tillage was analyzed by using the geographically and temporally weighted regression model. The results showed that (1) the net carbon sink of conservation tillage in China was significant and had potential to have a constant rise; (2) spatially, the net carbon sink of conservation tillage changed more variably in longitudinal direction. Specifically, the promotion effect of conservation tillage machinery gradually decreased from west to east. The planting structure and conservation tillage promotion intensity played key roles in improving net carbon sink of conservation tillage. (3) Temporally, the effect of conservation tillage machinery showed positive effect of decreasing yearly, while the positive effect of promotion intensity increased year by year. Planting structure and economic development negatively affected improvement on the net carbon sink of conservation tillage and the negative effect increased year by year. Additionally, the effect of education on the net carbon sink shifted from positive to negative over time. The study aims to provide a reference for the government to promote conservation tillage according to local conditions and to achieve the "dual carbon" target.

Effects of long-term tillage practices on the stability of soil aggregates and organic carbon in black soil farmland.

We examined the effects of different tillage practices on plough layer soil structure and organic carbon stabilization in black soil farmland with a long-term positioning platform. The wet-sieving method and infrared spectroscopy method were used to investigate the impacts of conventional tillage (CT), no-tillage (NT), sub-soiling tillage (ST), and moldboard plowing tillage (MP) on soil aggregates distribution and organic carbon characteristics in 0-40 cm soil layers. Compared to CT, both NT and ST treatments significantly increased the proportion of large macroaggregates (>2 mm) in the topsoil layer (0-20 cm)and that of small macroaggregates (0.25-2 mm) in the subsoil layer (20-40 cm) for NT, ST, and MP. NT, ST, and MP treatments resulted in higher mean weight dia-meter (MWD) and mean geometric diameter (GMD) of soil aggregates in both the topsoil and subsoil layers. NT treatment improved organic carbon contents in bulk soil and large macroaggregates in the topsoil layer, while ST and MP enhanced organic carbon contents in bulk soil and large macroaggregates in the subsoil layer. The contribution rate of small macroaggregates organic carbon content to the total was between 68.9% and 83.4%. Furthermore, the organic carbon chemical stabilization of soil body and aggregates increased in the topsoil and subsoil layers under NT treatment compared to others. The MWD had a positive correlation with the organic carbon content and chemical stability of soil body and small macroaggregates. These findings offered a theoretical basis for understanding the impacts of different tillage practices on the stability of soil aggregate and organic carbon in black soil region.

Ecosystem service value of conservation tillage with cover crop-maize intercropping in the black soil region of Northeast China.

Scientific evaluating ecosystem service value (ESV) of cover crop cultivation system can provide important guidance for the construction of conservation tillage pattern in Northeast China. Based on empirical analysis and the theory of ecosystem service value, we calculated the ESVs of intercropping maize with gramineous cover crop ryegrass and with leguminous cover crops, alfalfa and hairy vetch, with maize monoculture as the control. The ESVs included product supply, gas regulation, nutrient cycling, and soil and water conservation. Results showed that ESVs of cover crop-maize intercropping were higher than those of maize monoculture. Nutrient cycling value was the highest, followed by product supply value, accounting for 67.3% and 29.3% of total ESV, respectively. The nutrient cycling value of cover crop-maize intercropping was higher than that of maize monoculture. The product supply value of alfalfa-maize and hairy vetch-maize were 18.7% and 21.0% higher than that of ryegrass-maize, respectively. Cover crops had the potential to increase the value of gas regulation services, but had little impact on the value of soil and water conservation. Considering the ESVs, intercropping maize with leguminous cover crops would have the greatest benefits.

Effects of conservation tillage on soil enzyme activities of global cultivated land: A meta-analysis.

The negative impacts of conventional agriculture and the imperative to adopt conservation tillage garnered significant attention. However, the effects of conservation tillage on soil enzyme activities still lack comprehensive cognition. Here, we collected 14,308 pairwise observations from 369 publications worldwide to systematically evaluate the effects of different conservation tillage practices (reduced tillage (T), reduced tillage with straw return (TS), reduced tillage with straw mulch return (TSO), no-tillage (NT), no-tillage with straw return (NTS), and no-tillage with straw mulch return (NTSO)) on the activities of 35 enzymes in soil. The results showed that: (1) the effect of conservation tillage on soil enzyme activity varied by enzyme type, except for peroxidase (-12.34%), which showed an overall significant positive effect (10.28-89.76%); (2) the NTS and TS demonstrated strong potential to improve soil enzyme activities by increasing a wide variety of soil enzyme activities (12-15) and efficacy (9.76-75.56%) than other conservation tillage (8.60-68.68%); (3) in addition, the effect of conservation tillage on soil enzyme activity was regulated by soil depth, crop type, years of conservation tillage, climate (mean annual precipitation and temperature), and soil physicochemical properties (e.g., pH, bulk density, electrical conductivity, organic matter, ammonium nitrogen, total phosphorus, available phosphorus, total potassium, available potassium, etc.). Overall, our quantitative analysis clearly suggests that conservation tillage is an effective measure for improving soil enzyme activity on global croplands, where combination of reduced tillage or no-till with straw return are considered to have great potential and promise. The results contribute to better comprehend the effects of conservation tillage on soil activity and provide a valuable insight for agricultural management.

Conservation tillage practices affect soil microbial diversity and composition in experimental fields.

Introduction: Conservation tillage is a widely used technique worldwide, but the effects of conservation tillage on bacterial community structure are poorly understood. We explored proportional alterations in the bacterial community under different tillage treatments. Methodology: Hence, this study utilized high-throughput sequencing technique to investigate the structure and assembly processes of microbial communities in different tillage treatments. Results and discussion: Tillage treatments included tillage no-straw retention (CntWt), no-tillage with straw retention (CntWntS), tillage with straw retention (CntWtS), no-tillage and no-straw retention (CntWnt). The influence of tillage practices on soil bacterial communities was investigated using Illumina MiSeq sequencing. Different tillage methods and straw retention systems significantly influenced soil parameters such as total potassium and pH were not affected by tillage practices, while straw retention significantly affected soil parameters including nitrogen content, available phosphorus and available potassium. Straw retention decreased bacterial diversity while increased bacterial richness. The effect of straw retention and tillage on bacterial communities was greater than with no tillage. Phylogenetic ß-diversity analysis showed that deterministic homogeneous selection processes were dominated, while stochastic processes were more pronounced in tillage without straw retention. Ecological network analysis showed that microbial community correlation was increased in CntWntS and CntWnt. Straw retention treatment significantly increased the relative abundance of bacterial taxa Proteobacteria, Bacteroidetes, and OD1, while Nitrospirae, Actinobacteria, and Verrucomicrobia significantly decreased. Conclusion: The conservation tillage practices significantly affect soil properties, bacterial composition, and assembly processes; however, further studies are required to investigate the impact of different crops, tillage practices and physiological characteristics on bacterial community structure and functions.

Metagenomics reveals the abundance and accumulation trend of antibiotic resistance gene profile under long-term no tillage in a rainfed agroecosystem.

Widespread soil resistance can seriously endanger sustainable food production and soil health. Conservation tillage is a promising practice for improving soil structure and health. However, the impact of long-term no-tillage on the presence of antibiotic resistance genes in agricultural soils remains unexplored. Based on the long-term (>11 yr) tillage experimental fields that include both conservation tillage practices [no tillage (ZT)] and conventional tillage practices [plough tillage (PT)], we investigated the accumulation trend of antibiotic resistance genes (ARGs) in farmland soils under long-term no-tillage conditions. We aimed to provide a scientific basis for formulating agricultural production strategies to promote ecological environment safety and human health. In comparison to PT, ZT led to a considerable reduction in the relative abundance of both antibiotic resistance genes and antibiotic target gene families in the soil. Furthermore, the abundance of all ARGs were considerably lower in the ZT soil. The classification of drug resistance showed that ZT substantially decreased the relative abundance of Ethambutol (59.97%), ß-lactams (44.87%), Fosfomycin (35.82%), Sulfonamides (34.64%), Polymyxins (33.67%), MLSB (32.78%), Chloramphenicol (28.57%), Multi-drug resistance (26.22%), Efflux pump (23.46%), Aminoglycosides (16.79%), Trimethoprim (13.21%), Isoniazid (11.34%), Fluoroquinolone (6.21%) resistance genes, compared to PT soil. In addition, the abundance of the bacterial phyla Proteobacteria, Actinobacteria, Acidobacteria, and Gemmatimonadetes decreased considerably. The Mantel test indicated that long-term ZT practices substantially increased the abundance of beneficial microbial flora and inhibited the enrichment of ARGs in soil by improving soil microbial diversity, metabolic activity, increasing SOC, TN, and available Zn, and decreasing pH. Overall, long-term no-tillage practices inhibit the accumulation of antibiotic resistance genes in farmland soil, which is a promising agricultural management measure to reduce the accumulation risk of soil ARGs.