No-till Practices Research Articles

Stubble Quality of Wheat Grown under No-Tillage and Conventional Tillage Systems, and Effects of Stubble on the Fermentation Profile of Grazing Ewes’ Ruminal Fluid

Conservation practices that involve leaving mulch on the soil are known to increase soil fertility. However, mulch is an important source of feed for ruminant livestock. Accordingly, the trade-offs between mulching and stubble uptake by livestock are currently hot topics in the research field. In this study, a comparison between the quality of stubbles of wheat grown in no-tillage and conventional tillage fields and the rumen fermentation characteristics of Barbarine ewes grazing in the two fields was carried out. Samples were collected four times after wheat grain harvesting. Immediately after harvest, stubble biomass was slightly higher under no-tillage than conventional tillage. The ewes displayed different grazing behavior, with feeding at a higher rate on the conservative stubble than the conventional stubble. This feeding behavior seemed to be an adaptive strategy to offset the decline in the nutritional quality of stubbles from no-tillage-grown wheat. Indeed, dry matter, protein, fiber, and ash contents were lower in stubbles from no-tillage than conventional tillage at the second sampling time. Consequently, the concentration of the volatile fatty acid, propionic acid, was lower in ewes grazing in the conservative plots. However, this feeding behavior did not cause any body weight impairment during the two-month experimental period. At the end of grazing, the no-tillage practice was found to be comparable to the conventional tillage system according to the amount of residue remaining on the soil surface. Therefore, no-tillage could not be used to solve the competition between crops and livestock for residues.

Response of Fungal Sub-Communities in a Maize-Wheat Rotation Field Subjected to Long-Term Conservation Tillage Management.

Conservation tillage is an advanced agricultural technology that seeks to minimize soil disturbance by reducing, or even eliminating tillage. Straw or stubble mulching in conservation tillage systems help to increase crop yield, maintain biodiversity and increase levels of exogenous nutrients, all of which may influence the structure of fungal communities in the soil. Currently, however, the assembly processes and co-occurrence patterns of fungal sub-communities remain unknown. In this paper, we investigated the effects of no-tillage and straw mulching on the composition, assembly process, and co-occurrence patterns of soil fungal sub-communities in a long-term experimental plot (15 years). The results revealed that combine straw mulching with no-tillage significantly increased the richness of fungi but not their diversity. Differential abundance analysis and principal component analysis (PCA) indicated that tillage management had a greater effect on the fungal communities of abundant and intermediate taxa than on the rare taxa. Available phosphorus (AP) and total nitrogen (TN) were the major determinants of fungal sub-communities in NT treatment. The abundant fungal sub-communities were assembled by deterministic processes under medium strength selection, while strong conservation tillage strength shifts the abundant sub-community assembly process from deterministic to stochastic. Overall, the investigation of the ecological network indicated that no-tillage and straw mulching practices decreased the complexity of the abundant and intermediate fungal networks, while not significantly influencing rare fungal networks. These findings refine our knowledge of the response of fungal sub-communities to conservation tillage management techniques and provide new insights into understanding fungal sub-community assembly.

On-Farm Relationships Between Agricultural Practices and Annual Changes in Organic Carbon Content at a Regional Scale

Both soil quality degradation and climate change mitigation issues emphasize the need to increase, or at least stabilize, the topsoil organic carbon content (wt%) in arable land. This on-farm study aimed at measuring the impact of agricultural practices on changes in soil organic carbon (SOC) content over 10 years. A total of 120 fields belonging to 120 farms representative of the cropping systems and soil properties in Western Switzerland (Lake Geneva region) was randomly selected. The field 0–20 cm topsoil was sampled at a 10-years interval, and the corresponding cropping practices were gathered using farmer’s interviews and the mandatory records of yearly practices at field level in Swiss-farms. Only 1) organic matter inputs and 2) cover-crop intensity were significantly correlated to SOC increase while 3) the soil tillage intensity and 4) the soil saturation in carbon expressed as a SOC to clay content ratio were correlated to SOC decrease. Among others, temporary meadows were not correlated to changes in SOC content mainly due to increased tillage and decreased cover-crops between meadows. Organic farming did not correlate either with SOC changes due to the large tillage intensity applied for weed control. The observed SOC content changes ranged from −56‰ to +74‰ and were well explained by a linear regression model with additive effect of the four identified SOC change factors. The additivity of these factors means that farmers can emphasize the methods of their choice when regenerating their soils. This study advocates that strict no-till is not required at low carbon saturation level (small SOC:Clay ratio). However, as carbon saturation increases, conservation tillage and then no-till practices become necessary to further increase SOC contents. These findings are in accordance with previous studies showing that since 2015 SOC is increasing at more than +4‰ on average in the region and provide practical insights to further manage the transition of farming systems towards soil regeneration.

Effects of no-tillage practice for late-rice on rice yield and global warming potential in double-cropping rice systems

Effects of no-tillage practice for late-rice on rice yield and global warming potential in double-cropping rice systems

Impacts of fresh and aged holm-oak biochar on clomazone behaviour in rice cropping soils after transition to sprinkler irrigation

Although alternative practices to traditional flooding rice cultivation urgently need to be implemented in water-stressed regions, these can modify soil properties, thereby affecting the environmental behaviour of pesticides. One of the most extensively used herbicides in rice cropping is clomazone. A field experiment covering two years was conducted to evaluate how fresh and aged holm oak biochar (BH) influenced clomazone's behaviour in rice cropping after transition from flooding to sprinkler irrigation with different tillage systems. The experiment involved traditional flooding irrigation and tillage either without (FT) or with (FTBH) first-year BH addition, and four treatments more where sprinkler irrigation had been in use for 3 years – sprinkler irrigation and tillage without (ST) or with (STBH) first-year BH addition, sprinkler irrigation and no-tillage without (SNT) or with (SNTBH) first-year BH addition. The measurements done in the first and second years after BH application were taken to constitute the temporal variability (i.e., “fresh” and “aged” effects, respectively). Adsorption-desorption, dissipation, and leaching studies were carried out under laboratory conditions using soils from the field experiment. The Kd (partition coefficient) values were 1.2, 1.1, and 1.1 and 1.5, 1.2, and 1.2 times greater in SNTBH, STBH, and FTBH than in the corresponding unamended soils for the fresh and aged years, respectively. The clomazone persistence was only significantly affected by BH addition in the treatments under sprinkler irrigation. Under anaerobic incubation conditions the application of BH led to an increase in the t½ (half-live) values from 19 and 26 d and from 22 and 21 d in SNT and ST, to 36 and 35 d, and to 25 and 31 d in the corresponding amended soils for the fresh and aged years, respectively. However, under aerobic conditions, while for the fresh year t½ values increased from 37 and 41 d in SNT and ST to 40 and 52 d in the corresponding amended soils, for the aged year these values were not significantly affected. The management regimes significantly influenced clomazone leaching, with the total leached values showing the following trend: ST = SNT > FT = STBH = SNTBH > FTBH. Therefore, the use of BH as organic amendment may be an effective tool to greatly reduce water contamination by clomazone in rice fields under conventional tillage and flooding irrigation, but also under sprinkler irrigation, particularly after BH aging under no-tillage practices.

Long-term land use in Amazon influence the dynamic of microbial communities in soil and rhizosphere

Brazil has become the world leader in soy production, leading to an increase in the conversion of the Amazon rainforest into cropland. These actions had consequences for Forest's biodiversity, including the soil. In this sense, a better understanding of how long-term land use affects soil microbial communities, and their functions is urgent. This study aimed to evaluate the long-term land-use effects over bacterial and archaeal communities in soil and soybean rhizosphere in the Amazon region. For this, mesocosms experiments were carried out with Amazon soils with a history of 2-, 8-, and 20-years of agricultural use. We then assessed the bacterial and archaeal communities based on the 16S rRNA sequencing and real-time PCR. Our results showed a distinct bacterial community structure in soils with 20-years of land use. For both, bulk soil and soybean rhizosphere with 20-years of use, there was an increase in the abundance of Gemmatimonadetes, Chloroflexi, Firmicutes, and Planctomycetes. Interestingly, the niche occupancy analysis revealed an increase of specialist microbes in these soils. Also, these soils with 20-years of use showed a more complex network for both bulk and rhizosphere samples, highlighting the importance of Actinobacteria and Chloroflexi phyla to soil network structure. Our analysis also revealed an increased abundance of total bacteria, N-fixers, and ammonia-oxidizers bacteria in rhizosphere soil with 20-years of use. In addition, based on the potential functional analysis, nitrification processes increased in those soils. However, we noticed a homogenization in the abundance of the genes between rhizosphere and bulk soil with 20-years of use. In general, the differences were associated with changes in soil chemical characteristics such as pH, Ca2+, Mg2+, and organic matter, which are a consequence of liming and no-till practices over time. Our findings demonstrate that long-term agriculture in Amazon soils affects microbial community composition and functions, bringing new insights to better understand anthropogenic actions over the soil microbiome.

Zero-Tillage Effects on Durum Wheat Productivity and Soil-Related Variables in Future Climate Scenarios: A Modeling Analysis

Adoption of zero-tillage practices with residue retention in field crops has been introduced as an alternative soil-management technique to counteract the resource degradation and high production costs derived from intensive tillage. In this sense, the biophysical models are valuable tools to evaluate and design the most suitable soil-management technique in view of future climate variability. The aim of this study was to use the ARMOSA process-based crop model to perform an assessment of tillage (T) and no-tillage (No-T) practices of durum-wheat-cropping systems in the Campania region (South of Italy) under current and future climate scenarios. First, the model was calibrated using measurements of soil water content at different depths, leaf area index, and aboveground biomass in the T and No-T treatments during the 2013–2014 season. Then, the model was further applied in the T and No-T treatments to future climate data for 2020–2100 that was generated by the COSMO-CLM model using the RCP4.5 and 8.5 paths. Results of the calibration depicted that the model can accurately simulate the soil-crop-related variables of both soil-management treatments, and thus can be applied to identify the most appropriate conservation agricultural practices in the durum-wheat system. The simulation of soil water content at different depths resulted in small relative root mean square errors (RRMSE < 15%) and an acceptable Pearson’s correlation coefficient (r > 0.51); and the goodness-of-fit indicators for simulated LAI and AGB resulted in acceptable RRMSE (RRMSE < 28%), and high r (r > 0.84) in both soil-management treatments. Future climate simulations showed that No-T management will deliver 10% more wheat yield than the T, with an annual average 0.31% year−1 increase of soil organic carbon, and an increase of 3.80% year−1 for N uptake, which can diminish the N leaching. These results suggest that No-T could be implemented as a more resilient management for farming system in view of climate uncertainty and scarcity of resources. Therefore, these findings support the potential of the ARMOSA model to evaluate the soil-crop response of the durum-wheat system under different management conditions and to design appropriate soil-management practices for current and future climate predictions.

Greenhouse gas emissions from the wheat-maize cropping system under different tillage and crop residue management practices in the North China Plain

With increasing attention being placed on mitigating global warming and achieving agricultural sustainable intensification, conservation agriculture practices have gradually been implemented in the North China Plain (NCP). However, there are still knowledge gaps on the effects of conservation practices on greenhouse gas (GHG) emissions in this area. In this study, a four-year field experiment was conducted from 2014 to 2018 to assess the effects of tillage and crop residue management practices on the emissions of nitrous oxide (N2O) and methane (CH4). Subsequently, crop yields, area-scaled and yield-scaled total non-carbon dioxide (CO2) GHG emissions were assessed. Our research found that no-till (NT) decreased N2O emissions by 22.6% compared with conventional tillage (CT) in winter wheat (Triticum aestivum L.) seasons, but there was no difference between tillage practices in summer maize (Zea mays L.) seasons. Crop residue retention practice (+R) increased N2O emissions by 28.1% and 26.7% compared with residue removal practice (−R) in winter wheat and summer maize seasons, respectively. The NT soils took up more CH4 compared with the CT soils in summer maize seasons. Area-scaled total non-CO2 GHG emissions showed trends similar to those of N2O emission. Since crop residue retention improved the maize yield compared with the residue removal treatments, yield-scaled total non-CO2 GHGs emission did not differ between residue management practices in summer maize seasons. Our four-year field measurements indicated that no-till practice could be more useful as an option to mitigate non-CO2 GHG emissions in the wheat – maize cropping system.

No-tillage sorghum and garbanzo yields match or exceed standard tillage yields

To meet the requirements of California's Sustainable Groundwater Management Act, there is a critical need for crop production strategies with less reliance on irrigation from surface and groundwater sources. One strategy for improving agricultural water use efficiency is reducing tillage and maintaining residues on the soil surface. We evaluated high residue no-till versus standard tillage in the San Joaquin Valley with and without cover crops on the yields of two crops, garbanzo and sorghum, for 4 years. The no-till treatment had no primary or secondary tillage. Sorghum yields were similar in no-till and standard tillage systems while no-till garbanzo yields matched or exceeded those of standard tillage, depending on the year. Cover crops had no effect on crop yields. Soil cover was highest under the no-till with cover crop system, averaging 97% versus 5% for the standard tillage without cover crop system. Our results suggest that garbanzos and sorghum can be grown under no-till practices in the San Joaquin Valley without loss of yield.

Artificial macropore installation and no-tillage practice in subtropical sugarcane field to conserve water and organic matter in soils

Artificial macropore installation and no-tillage practice in subtropical sugarcane field to conserve water and organic matter in soils

The lagging movement of soil nitrate in comparison to that of soil water in the 500-cm soil profile

The combination of forage-crop rotation with conservation tillage has long been known to result in proven productivity and sustainability, but less information is available on the influence of long-term conservation tillage practices on the movement of soil water and residual nitrate at deep soil depths in forage-crop rotation systems. In this study, we measured the changes in soil water storage, residual soil nitrate accumulation and their relationship to study the long-term effects of tillage and mulching practices on regional nitrogen management in maize (Zea mays L.)-wheat (Triticum aestivum L.)-common vetch (Vicia sativa L., annual legume forage) rotation system. Soils were collected from the 500-cm soil profile at the harvest stage of the maize and common vetch after 19 years of continuous conventional tillage (T), conventional tillage followed by straw mulching (TS), no tillage (NT), and no tillage followed by straw mulching (NTS) on the Loess Plateau, China. The results showed that the NT practices increased soil water storage by 3.07% compared with the T practices in the maize field, mulching practices increased soil water storage by 3.47% compared with no mulching practices in the common vetch field, and the improvement effect was mainly concentrated in the deep soil layer (150–500 cm). When compared with no mulching, straw mulching practices increased residual soil nitrate accumulation by 51.20 kg ha−1 at shallow soil depths (0–120 cm) but decreased this accumulation by 206.09 kg ha−1 at deep soil depths (120–500 cm) in the maize field; however, straw mulching decreased nitrate accumulation by 16.25 kg ha−1 throughout the whole profile (0–500 cm) in the common vetch field. The NT practices decreased residual soil nitrate accumulation by 131.65 kg ha−1 compared with the T practices in the maize field but had no effects on the common vetch field in the 0–500-cm soil profile. Greater changes in soil residual nitrate accumulation appeared at depths of 200–500 cm than at other depths. Moreover, according to structural equation model, nitrite accumulation was limited by soil water storage. Soil nitrate peaked at deeper soil depths in the NT (90–120 cm) and TS (250–300 cm) treatments than in the T treatment (60–90 cm), whereas the NTS treatment resulted in no nitrate accumulation peak across the whole soil profile. Soil water recharge and depletion were deeper in the NT and TS treatments than in the T treatment, and this effect could limit the further leaching of soil nitrate into deep soil. The depth of soil water recharge was deeper than the depth of nitrate accumulation, and the vertical movement speed of soil residual nitrate was slower than that of soil water. Therefore, the downward movement of soil nitrate lagged behind that of soil water. Together, these results demonstrated that the NTS treatment exerted the strongest effect on maintaining soil water and decreasing residual nitrate accumulation at deep soil depths, which will be favorable for improving regional N management and assessing N budgets in agroecological systems on the Loess Plateau.

Soybean (Glycine max (L.) Merr.) Growth, Yield, and Nodulation in the Early Transition Period from Conventional Tillage to Conservation and No-Tillage Systems

Soybean (Glycine max (L.) Merr.) is the most important protein crop globally, with its cultivation area in Europe on the increase. To investigate how alternative tillage systems affect soybean growth, yield performance, and nitrogen fixation capacity in the early conversion period from conventional tillage to conservation and no-tillage practices, a field study was conducted in 2020 under the humid central European climatic conditions of Slovenia. A complete randomized block design with four repetitions was used for the three different tillage systems (conventional, conservation, and no-tillage). The results show that the majority of the studied soybean growth parameters (e.g., plant density, nodes per plant, and shoot and root dry matter) and the yield components (e.g., pods per plant, and 100-seed mass) were greatest for the reference conventional tillage system. The conventional system also showed significantly greater dry nodule mass (p < 0.01) and proportion of large-sized nodules (>4 mm) on both the tap root (p < 0.05) and the lateral roots (p < 0.001). A positive linear correlation between nitrogen content and nodule production in the roots also suggested increased nitrogen fixation for the conventional system. The less intensive conservation and no-tillage systems resulted in significantly greater soil compaction, which negatively affected early plant establishment and resulted in significantly decreased plant densities. Despite the large differences in plant stands and individual plant performances, no significant differences were seen for dry seed yields between these tillage systems. Dry seed yields for the conventional and conservation systems were 4.54 and 4.48 t ha−1, respectively, with only minor (non-significant) yield reduction for the no-tillage system, at 4.0 t ha−1. These data show that soybean cultivation in the early transition period to less intensive tillage systems have no major yield losses under these less suitable agro-climatic conditions if correct crop and weed management measures are implemented.

Stratification of soil phosphorus forms from long-term repeated poultry litter applications and its environmental implication

Increasing demand for poultry products has led to an intensification of concentrated poultry feeding operations resulting in the generation of enormous amounts of poultry litter (PL). For example, in 2017 the southeastern U.S. alone generated 9.35 million U.S. tons of broiler litter. Repeated applications of PL along with no-till practices in agricultural fields located in high-density poultry operation regions often result in buildup of soil phosphorus (P) and raise environmental concerns. Less is known about how P forms such as highly reactive P (HRP), moderately reactive P (MRP), and non-reactive P (NRP) are stratified in soil layers and their potential environmental P loss risk in no-till agricultural lands that have a long-term history of PL applications. The objectives of this study were 1) to quantify the vertically distributed P forms in distinct soil depths; 2) identify the relationship between P forms and extractable P, and 3) understand the relationship between different P forms and the P saturation ratio (PSR) in PL impacted soils. Soil samples from the Madison series (Fine, kaolinitic, thermic Typic Kanhapludults) with an average 10-year PL application history on no-till agricultural fields were collected from four depths (0–5, 5–15, 15–30, and 30–45 cm) and P forms were determined using Hedley fractionation procedure. The P forms were found highly stratified within the soil layers, where the surface soils (0–5 cm) had an average of 20% of total P present in HRP, 50% in MRP, and 30% in NRP. The percentages of HRP and MRP forms decreased significantly and NRP became the dominant P form down the soil depth (15–30 and 30–45 cm). Multiple regression analysis indicated oxalate extractable P (Ox-P) represented all the three P forms (HRP, MRP, and NRP) and can be used as an index of long-term P availability. The PSR decreased down the soil profile and was linearly associated with HRP and MRP but not with NRP. Subsurface application of PL in regions where repeated loadings cannot be avoided would require careful evaluation of distinct P forms (reactive vs. non-reactive) along with the determination of soil PSR for the subsurface soil depths.

Furrow-irrigated corn residue management and tillage strategies for improved soil health

Conversion from conventional tillage to no-till in surface irrigated agroecosystems is low, mostly due to difficulties crop residue creates for water surface flow if no-till is implemented. A three-year continuous corn (Zea mays L.) study was conducted to evaluate the effects of residue management (retained yet mechanically moved out of the irrigation furrow, grazed, or baled/removed) and tillage (conventional tillage versus no-till) on soil health as verified using the Soil Management Assessment Framework. After three years of implementation, corn yields were 15% greater under no-till as compared to conventional tillage (13.1 versus 11.4 t ha−1), and followed the order baled (13.6 t ha−1) > grazed (12.5 t ha−1) > retained (10.6 t ha−1). In terms of corn residue management, soil health followed stover grazed = stover retained > stover baled/removed, a function of lower salts and greater plant-available K, beta-glucosidase activity, potentially mineralizable N, and microbial biomass C present – a result of greater water-stable aggregates and grazing’s influence on K and organic inputs. Reduced soil physical health was associated with a short-term increase in bulk density under no-till, while improved soil chemical health was associated with reductions in soil salts under no-till. Greater soil biological health was noted in the soil surface with no-till, due to greater beta-glucosidase activity, microbial biomass C, and a slight increase in soil organic C; the opposite was found with conventional tillage and soil depth. However, when combining the above observations, greater overall soil health was observed in the upper soil as associated with no-till as compared to conventional tillage; subsoil had greater overall soil health associated with conventional tillage. Understanding the importance of crop residue utilization in conjunction with no-till practices in surface irrigated agroecosystems can influence the adoption of sustainable management practices and should directly contribute to long-term soil health improvements and agroecosystem sustainability.

Long-term organic and conventional farming effects on nutrient density of oats

AbstractDeclining nutrient densities of crops in the past 50–70 years have been attributed to unsound agricultural practices and plant breeding focus on yield rather than quality. Few studies have quantified the soil and nutritional quality of grains in organic and conventional farms and reported results are scarce and inconsistent. The Rodale Institute's Farming Systems Trial (FST) was established in 1981 to quantify the effects of long-term organic and conventional grain cropping systems and tillage practices. A 2014 study to quantify effects on the nutrient density of oat grains was integrated into three systems within the long-term trial: organic manure-based (MNR), organic legume-based (LEG), and conventional synthetic input-based (CNV), split between tilled (T) and no-till (NT) practices. Oat grains with hulls removed were analyzed for minerals (n = 24), vitamins (n = 24), amino acids (n = 24) and proteins (n = 24), while soil samples to a depth of 10 cm were analyzed for elemental minerals, and total carbon (C), nitrogen (N) and sulfur (S). Organic systems increased six out ten soil minerals whose concentrations were influenced by cropping systems: aluminum (Al), iron (Fe), chromium (Cr), calcium (Ca), barium (B) and strontium (Sr). All essential amino acids were greater in oat grains under LEG systems compared with other systems except lysine, histidine and methionine. Both LEG systems also increased 12 out of 13 non-essential amino acids in oat grains. Total oat N, C and S required for amino acid synthesis tended to be greater in organic systems. Soil N, C and S were highly correlated with total oat amino acids under organic systems compared to CNV. Organic LEG had significantly greater vitamin B1 than MNR and CNV. These results suggest that nutrient concentrations of oat grains were greater in organic systems compared to CNV systems, and the increase could be partially explained by the long-term soil management differences between the systems.

Carbon Sequestration to Avoid Soil Degradation: A Review on the Role of Conservation Tillage.

Human efforts to produce more food for increasing populations leave marks on the environment. The use of conventional agricultural practices, including intensive tillage based on the removal of crop residue, has magnified soil erosion and soil degradation. In recent years, the progressive increase in the concentration of greenhouse gases (GHGs) has created global interest in identifying different sustainable strategies in order to reduce their concentration in the atmosphere. Carbon stored in soil is 2–4 times higher than that stored in the atmosphere and four times more when compared to carbon stored in the vegetation. The process of carbon sequestration (CS) involves transferring CO2 from the atmosphere into the soil or storage of other forms of carbon to either defer or mitigate global warming and avoid dangerous climate change. The present review discusses the potential of soils in sequestering carbon and mitigating the accelerated greenhouse effects by adopting different agricultural management practices. A significant amount of soil organic carbon (SOC) could be sequestered by conversion of conventional tillage to conservation tillage. The most important aspect of conservation agriculture is thought to improve plant growth and soil health without damaging the environment. In the processes of climate change mitigation and adaptation, zero tillage has been found to be the most eco-friendly method among different tillage techniques. No-till practice is considered to enable sustainable cropping intensification to meet future agricultural demands. Although no-tillage suggests merely the absence of tillage, in reality, several components need to be applied to a conservation agriculture system to guarantee higher or equal yields and better environmental performance than conventional tillage systems.

Global meta-analysis suggests that no-tillage favourably changes soil structure and porosity

Role of soil to meet global food security, sustainable intensification and food nutritional quality has got renewed attention with a larger focus on soil physical condition. No-tillage (NT) practice can essentially contribute to develop a sustainable, low carbon and resource efficient agriculture, and encourage the use of crop residues for added soil benefits. Soil aggregation and pore size distribution, two most important soil physical factors controlling the mass and energy transport processes within the soil and between soil and environment, were evaluated under the NT through a global meta-analysis of 5065 pairs of data points from 419 peer-reviewed studies. Compared to conventional tillage (CT), NT increased mean weight diameter of aggregates, water stable aggregates, and macroaggregates by averages (0–30 cm) of 25, 10 and 22%, respectively, although predominantly in 0–10 and/or 10–20 cm layers, with an accompanying reduction in microaggregates. A small but significant 3% decrease in total porosity, a large reduction (20–32%) in macroporosity and a moderate increase (4–7%) in microporosity were realized under NT up to 20 cm soil depth. Bulk density remained stable, although a very large decrease (70% change over CT) in saturated hydraulic conductivity was recorded in 10–20 and >30 cm soil layers. Years of adoption of NT had an additive effect on mean weight diameter and macroaggregates, and the total and macroporosity. Increase in latitudes favoured soil aggregation and micropore volume under NT, while clay content was unfavourable to macro- and water stable aggregate contents. Improvement in structure and water retention properties relate to long-term sustainable development of soils by following no-till practice, which has far-reaching implications beyond the boundaries of agronomy.

Inherent and dynamic effects on the structural stability of Brazilian Oxisols

We assessed long-term cultivation effects on several structural stability indicators within the 0- to 5- and 10- to 15-cm depth increments of different Oxisols. Comparisons were made between native and cultivated soils managed using no-till (NT) practices for 12+ years. Overall, conversion significantly decreased structure stability due to machinery traffic, high fertilizer and lime applications, soil organic matter (SOM) depletion, and reduced input of organic material (roots and crop residues). The magnitude of change varied depending on inherent (mineralogy) and dynamic (cropping system) factors, as well as soil depth. Kaolinitic Oxisols were much more susceptible to degradation than Gibbsitic Oxisols. Combining more diversified cropping systems with NT can mitigate the negative effects of cultivation by increasing living vegetation and crop residue additions throughout the entire year. Increased quantity and quality of SOM input improves soil biological activity and improves topsoil structural stability. Those changes also reduce eluviation of dispersed clay (primarily kaolinite) with percolating water and prevent concentration of the clay at the 10 to 15 cm depth, which further degrades the soil by contributing to formation of the dense subsurface layers beneath either NT or conventional production systems.

Quantification of resilience metrics as affected by conservation agriculture at a watershed scale

It is suggested that conventional tillage operations exacerbate global environmental changes and affect the sustainability of our food production systems. Therefore, no-till has been introduced as one of the conservation agriculture practices to counteract these challenges. No-till has been adopted by a substantial number of farmers in major cropping regions; however, its resilience from large scale implementation has been overlooked. The majority of the studies have reported only a few aspects of the no-till practice (e.g., yield, soil properties, etc.), often with contradicting observations. To fill this gap, we present an approach that integrates long-term field experimental data and modeling to quantify resilience at a watershed scale. The study was conducted in the Kalamazoo River watershed located in Michigan, USA. Recharge, groundwater table, soil moisture, yield, and net return were used as resilience metrics. The DSSAT sequence crop model was developed for a corn-soybean-wheat rotation and calibrated using the yield and soil moisture data from a long-term (1993–2019) experiment for the conventional and the no-till treatment conducted within the study area. Soil moisture, recharge and yield were simulated, and the recharge was fed into a calibrated groundwater model to analyze changes in groundwater heads. The results illustrate clear evidence of higher recharge and net return under the no-till treatment, which were statistically significant for all crops at the watershed scale. Moreover, the no-till treatment consistently retained greater soil moisture than the conventional treatment, thereby helping to mitigate the impacts of droughts. The rise in groundwater table as affected by the adoption of no-till practices in this watershed has ranged between 0.1 and 0.5 m, depending on the underlying groundwater system, and has the potential to beneficially affect the aquifers and groundwater-dependent ecosystems. Therefore, the conservation agriculture could improve the overall resilience of the row crop system.

Soil health changes from grassland to row crops conversion on Natric Aridisols in South Dakota, USA

In the northern Great Plains vast amounts of native grassland have given way to crops, mostly small grains and corn, over the past half century. It is well understood that over the long-term, grassland conversion accelerates erosion and generally decreases many soil functions. It is less clear, however, what short-term effects occur to the soil from grassland conversion; after the first or second year of conversion. The objectives of this study were to assess the short-term (first year) effects of converting land that is considered long-term grassland to small grain production through either conventional tillage (CT) or no-till (NT) practices using various indicators of soil health and to demonstrate how tools such as the Comprehensive Assessment for Soil Health (CASH), can be used to document soil health indicator decline immediately upon conversion from grassland to small grains. The CASH offers a suite of chemical, physical and biological soil tests to broadly assess soil health. In general, these indicators showed a more rapid decline in soil health under CT than NT. After the first year of grassland conversion, aggregate stability declined by 7% and 19% in the NT and CT plots, respectively when compared to the grassland control. Likewise, CT produced significantly greater declines in permanganate oxidizable carbon (POX-C) and soil protein (ACE-Protein), particularly under reduced precipitation. This study highlights how the CASH can provide an intuitive framework for monitoring the effects of land use change and can be used by land managers to identify potential soil constraints and formulate potential interventions.