Conservation Agriculture Research Updates - March 2026

This another report for a long-term experiment (60 years) from the Triplett Van-Doren No-Tillage and Crop Rotation Experiment established in 1962 in Wooster, Ohio, USA that was designed to evaluate the impact of no-tillage and crop rotation on corn and soybean yields. This experiment is conducted on two contrasting soils, one well-drained and one poorly drained. There were 3 tillage practices; moldboard, chisel and no-till with the residue from the previous crop left in the field and 3 rotations; continuous maize, a 2-year maize-Soybean, and a 3 year maize-forage-forage. Crop rotation was the main driver of long-term crop performance, with the most favorable responses observed when forage crops were included in the cropping system at both sites. Note the forage crops contained mixtures with legumes. The paper contains a lot of interesting data. They conclude that " By evaluating long-term trends, we found that no-tillage can be viable even in clay soils under temperate climates when perennial crops are included in the rotation system. Our results demonstrate that longterm crop yields can significantly benefit from the implementation of both practices adopted together in cropping systems."

This is another article from the Central Valley of California that assesses 20 years of conservation agriculture management that looks at soil physical, chemical and structural properties comparing reduced tillage with cover crops with conventional tillage without cover crops. In brief, the CA management achieved dynamic equilibrium characterized by fundamental shifts in carbon stabilization pathways. Water stable aggregates also exhibited 136% greater stability with CA than with CT. This paper discusses the implications of these differences. They conclude "This mechanism shift represents a new soil system equilibrium that maintains enhanced functionality and continued carbon sequestration potential in Mediterranean agricultural systems."

This paper from North America synthesized data from 30 meta-analyses to comprehensively assess the impacts of the no-till (NT), reduced till (RT,) and mixed NT+RT on crop yields and GHG emissions. Results showed that the yields of wheat, maize, rice, fibers, cotton, and cereals were not significantly affected by NT, while the yields of soybean, oilseeds, and legumes were enhanced by NT. NT did not influence soil CO2 emissions, and none of the tillage treatments influenced soil CH4 emissions. However, NT increased soil N2O emissions whereas RT and NT+RT had no significant effect on soil N2O emissions. They suggested that the varied impacts of tillage can be attributed to soil properties and practices like crop residue management, irrigation type, and nitrogen rates. 

This paper from Ohio State University's Triplett-Van Doren long-term tillage and crop rotation experiment (one of the oldest NT experiments in the World) looked at the temporal dynamics of soil N and C pools in a maize growing season, in a 55 year old tillage and crop rotation experiment. Tillage treatments were no-till (NT) + residue, Chisel-till (CT) + 30% residue and moldboard till (MT) - residue incorporated. There were 3 rotations: continuous maize, maize-soybean (2-year rotation), and maize-forage-forage (3 year rotation). Their results suggest that crop diversification with perennials enhances soil C and N; NT has stronger effects in clay loam than silt-loam soils; and although C and N pools vary seasonally, long-term management effects persist throughout the growing season.

This study was done in the US upper Midwest over 3 years. There were 15 field pairs with one using conventional (CM) and the other soil health management (SH) (reduced tillage, cover crops and crop diversity). They assessed these plots by looking at soil organic matter pools, microbial indicators and a physical indicator. Wet aggregate stability improved in the SH plots compared to the CM ones. Results showed that most soil properties were significantly responsive to two management combinations, 1) tillage x cover crops, and 2) tillage x cover crops x crop diversity. Microbial indicators along with potentially mineralizable nitrogen (PMN) exhibited the strongest increases in the SH plots.

This paper from Canada looks at application rates of Glyphosate (GBH) to terminate cover crops and how this influences soil microbial communities. They used 3 GBH application rates in maize, soybean and wheat fields grown with direct seeding (NT) with and without cover crops. Results showed that DS+CC did not significantly impact microbial richness compared to DS, but did alter specific abundance among prokaryotes and eukaryotes but that the three crops significantly influenced the composition of eukaryotic communities in 2018 and 2019, but not prokaryotic communities. They conclude that the study calls for sustainable agricultural practices that preserve microbial diversity, which is essential for maintaining ecosystem services and soil health.

This study used 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 using  environmental drivers acquired from different remote sensing datasets for 2022 and 2023 to map conservation agriculture practices. They successfully detected the presence of cover crops and the tillage intensity in the study region. Their analysis shows the percent use of cover crops in maize and soybeans and adoption of CA tillage practices. This approach benefits both public and private sector organizations by enabling them to track landscapes remotely and efficiently. This, in turn, can incentivize farmers to adopt conservation practices, contributing to climate change mitigation efforts and fostering sustainable agricultural development.

This paper from the US used an integrated energy-economy-land-climate model to assess the global land, trade, and emissions impacts of an adoption of domestic no-till farming and cover cropping practices based on carbon pricing. They found that adoption of these practices depends on which aspects of terrestrial carbon are valued. For example valuing afforestation comes at the expense of agricultural production. In contrast, a policy valuing soil carbon in agricultural systems specifically indicates strong adoption of no-till and cover cropping for key crops. They conclude that "adoption of no-till and cover cropping practices in the US could increase the terrestrial carbon sink with limited effects on crop availability for food and fodder markets." The paper ends with suggestions for further research.

This paper has created a database using 218 response variables from the following 5 common categories of CA from the Mid-Western USA from 1980-2020: cover crops, tillage management, pest management, nutrient management, and crop diversification. The data was collected from the Web of Science. They also have summarized all this data on a web site, https://www.agevidence.org/

They conclude that this web site and database will be useful for the many stakeholders involved in making decisions on how to make more food with less environmental impact.

Since Glyphosate herbicide is important for weed control in CA and is receiving a lot of negative press, I have included this research paper. It discusses both urban and agriculture sources for this herbicide. They investigated long-term concentrations of glyphosate and main transformation product aminomethylphosphonic acid (AMPA) in a large meta-analysis of about 100 sites in the USA and Europe. The U.S. data reveal pulses of glyphosate and AMPA when the discharge of the river is high, likely indicating mobilization by rain after herbicide application. In contrast, European concentration patterns of glyphosate and AMPA show a typical cyclic-seasonal component in their concentration patterns, correlating with patterns of wastewater markers such as pharmaceuticals, which is consistent with the frequent detection of these compounds in wastewater treatment plants. They suggest as in the title of this paper that in Europe glyphosate  contamination in rivers is not from application in agriculture.

This paper looks at maize yield impacts conservation tillage (CA?) from satellite data from 4 States of the US Corn Belt from 2008-2020. Data was obtained from several thousand fields with differences in climate, soil quality and irrigation status. Their results show overall that long-term adoption of CA increased rainfed maize yields by almost 10% in the area covered. When analyzing the variables, the increase in maize yields were associated with improved water infiltration and retention. But many fields that could benefit from no-till have not adopted yet. They can now strengthen the reasons and areas suitable for benefits from CA. Benefits can be obtained without negative crop yields in most cases. They did say in the paper that NT combined with cover crops amplified the benefits.

This desktop research project reviewed the literature  on CA practices and their affects on soil health and productivity in the Midwest of USA. They looked at on-farm application of CA practices; compiled data on diverse farming systems using conventional and CA practices; and identified knowledge gaps where corn-soybean was the dominant cropping system. Major knowledge gaps were identified that need to be included in future research on farming practices that improve soil health.

Strip tillage is gaining a lot of attention from farmers in the USA so I chose this article from a study in the USA (Alabama following Cotton) for readers of my CA newsletter. The objective of their study was to assess the effects of different tillage practices including strip tillage on soil pore properties. Undisturbed soil columns were collected during two seasons comparing ST with CT. Overall the study showed taht pore morphology can be affected by tillage and seasonal aspects associated with them.

This paper presents some of the data from  a family farm in Ohio, one of the oldest continuous NT and cover crops adapted farms in Ohio since 1971. The objective of the study was to assess the effects of no-till (NT) management over 0, 6, 20, and 35 years in a rainfed corn-soybean system, incorporating cereal rye as a cover crop, on soil organic C (SOC) sequestration and total N accumulation across different pools. The results show a significant increase under NT compared to conventional for SOC, total N, microbial biomass C, active C, passive C, particulate organic C and N. They conclude that "long-term NT consistently facilitates SOC sequestration and total N accumulation in different pools, with these benefits distributed non-linearly across distinct SOC and total N pools at the 0-15 cm depth and linearly at the 15-30 cm depth in rainfed corn-soybean systems."

This article describes the history of California's Conservation Agriculture Systems Innovation (CASI) that increased the sustainability of agriculture in the San Joaquin Valley of California, by reducing soil erosion, conserving soil moisture, using systems thinking, creating farmer networks, advisors, and researchers since 1998. It used CA management that included reducing soil disturbance for better soil structure and biological activity, retaining biomass on the soil to support soil life, and diversifying crops to enhance biodiversity. They calculate that CASI involves more than 2200 farmers and private sector, university, public agency and environmental groups as partners. The paper describes the benefits of CA in maize, small grains, vegetables, cotton, beans, and melons. They conclude that "reducing soil disturbance for better soil structure and biological activity, retaining biomass on the soil to support soil life, and diversifying crops to enhance biodiversity."

The Intergovernmental Panel on Climate Change projects an increase in temperature and the frequency of high-intensity rainfall events in the future in most parts of the world. NT was suggested by the UN missions Gap Report as a potential measure to mitigate the negative effects of climate change. This paper from Texas using the APEX model studies the effectiveness of NT in improving resilience of agricultural watersheds to extreme climatic conditions in comparison to conventional tillage (CT). Results showed that NT was significantly effective in reducing annual soil evaporation, surface runoff, and soil erosion and also maintaining rainfed corn yields compared to CT. During high rainfall events NT also minimized runoff and sediment erosion. The authors feel NT needs to be promoted in these climatic conditions.

This 4-year study in the Lower Mississippi Delta on farm size plots compared soybean yield and soil health benefits comparing CT with NT. Both plots were under maize for 11 years prior to growing soybeans using CT and NT soil management for each plot. Results showed that NT compared to CT, in the 0-20 cm layer, increased soil bulk density (rho), total nitrogen (TN), and soil organic carbon (C) but field-saturated hydraulic conductivity (Kfs) decreased in the 10 cm below the soil surface under NT. Yields of soybeans over the 4 years were similar for CT and NT plots. But NT resulted in less expenses without affecting soybean yields.

This paper looks at land in the Lower Mississippi Delta where 70% of the land is furrow irrigated and where NT and bed planting issues hinder NT adoption. Ridge making and furrow maintenance are crucial in this area. This paper looked at the impact of adopting long-term NT compared to conventional tillage (the traditional system). NT increased soil total nitrogen, organic matter, organic sulfur, magnesium, calcium, cation exchange capacity, and stored soil water compared to CT during 4 years of soybean production following 11 years under corn. CT resulted in loss of nutrients as a result of disturbing the soil surface. CT also developed a thick plow pan at 10cm depth. I wonder if they should think of having permanent NT beds with residue retention that is practiced successfully in other parts of the World.

CA is being used in this coastal area of the USA to improve soil health, reduce environmental impacts, and improve farmer profits. They commonly use cover crops, strip, minimal, and no tillage. The paper evaluates the changes in soil properties from various CA  practices. They evaluated 4 tillage systems: conventional, strip, minimal, and no-tillage; 3 winter cover crop systems; fallow, winter cash crop, and high biomass CC. They then measured 6 soil properties over 7 years. Altogether, soil carbon showed a more consistent response to conservation management than the other soil properties, which tended to show greater variability based on the time since tillage. They conclude that conservation practices need to be applied for multiple years in order to improve soil properties. 

This review of the financial implications of CA in North America was gathered from existing research on the financial impacts of conservation practices on production systems in the Upper Midwest region of USA. The research includes national statistics from the United States Department of Agriculture’s (USDA) Census of Agriculture and the National Cover Crop Surveys. Sources at the regional and state level come from Extension reports, multi-farm
case studies, on-farm comparison trials, and State Department of Agriculture reports. Like other systems-level changes, transitioning to conservation agriculture practices involves new expenses, learning, and time. The information in this booklet shows that these investments have the potential to reduce farm costs, increase yields in some cases, and ultimately increase net income. Some practices can realize benefits in the first few years, while others take longer to build soil health.

Since plant residues are important for CA no-till management, I chose this paper that looks at the Global impact of cover crops in farming systems. CA plus cover crops is gaining popularity among farmers in the USA. This study assessed the global impact of cover crops on yield. They reviewed 104 articles to collect field based yield data (1027 records) to quantify the impact of CC's on main crop yields. Their data showed that CC's led to an overall increase in major crop yield of 2.6%. The utilization of leguminous cover crops, cultivation in coarse soil texture and dryland areas, and the implementation of longer cover cropping duration were found to be conducive scenarios to enhance crop yields. Conversely, the use of non-legume cover crops, introducing them to fields under a short-term no-till system, especially in fine-textured soils, lowered main crop yields. More data is available in the paper but they conclude that understanding and comprehensive information advances the appropriate and targeted adoption of cover crops for policymakers, extension services, and farmers.

This meta-analysis compares the yield and nitrogen use efficiency (NUE) between conservation tillage (CA?) and conventional (CT) for different cropping systems , mulching methods, N levels and addition of manure in US and China. The results show that CA at high-N enhanced the yield and NUE, and reduced the yield and NUE at low-N, compared to CT. NT with leguminous cover crops (LCC) significantly increased wheat yield NUE under low-N compared to CT. They conclude that based on the results, moderate N with LCC and manure application is recommended for growing winter wheat in dryland regions of the USA and China.

This paper describes an integrated 10-year CA cotton experiment in Louisiana, USA, using cover crops plus NT instead of conventional tillage (CT) that was assessed cotton yield using a biogeochemical denitrification-decomposition model. 4 cover crops were used: hairy vetch, winter wheat, native grass (NG) and crimson clover. It also had 4 nitrogen levels (0, 50, 100, 150 kg N/ha). They also estimated carbon sequestration and ecosystem functionality. Their results using the scenario analysis showed that 50kg N and a single irrigation was most beneficial for maximizing the cotton yield with cover crop incorporation in the NT system over long term. They conclude that implementation of a cover crop or crop residue system instead of increased N application, seed rates, and irrigation events under NT practices would be beneficial.

This study, initiated in Canada in 1992, evaluated the effect of 25 years of N and P fertilizer application and tillage (Moldboard vs No-till) on density, biomass and composition of weeds before and after herbicide application in maize (2016) and Soybean (2017). It also evaluated the same treatments 6 years later in maize (2022). comparing  weeds found in 2004 all weed variables increased and there were more grassy weeds in both tillage treatments. No fertilization effect was observed on any weed variables, including composition, except for increased biomass when left to grow all season after crop planting. No till had higher density and biomass of both annuals and perennials before herbicide application but only reduced yield in soybean.

This paper looks at nitrous oxide (N20) emissions in relation to soil pores under long term CA practices. Soil cores were extracted from CT and NT plots and cover crop (CC) hairy vetch (HV) and no CC (NV) and used for N20 measures. Their results show CT and HV emitted more N20 than NT or NV and for macroporosity, NT and NV increased these more than CT and HV. They conclude that N2O emissions were positively and significantly correlated to relative soil gas diffusivity, CT-derived macroporosity, number of macropores, and fractal dimension.