Conservation Agriculture Research Updates - March 2026

This article looks at the impact of conservation tillage in maize in the Karst rocky region of SW China where desertification is a serious environmental problem. This 2-year study compared no-till + straw cover against traditional tillage (TT) in maize on soil properties and yield. The NT treatment increased soil moisture by 3% while reducing bulk density by 7% and total N by 5% in the top 30cm compared to TT. Nt treatments also increased maize yield by11% compared to TT. They conclude that NT + residue retention is  better for long-term environmental sustainability in the arid region.

This paper looks at residue management that is difficult to manage in modern agriculture without burning and can lead to late planting. This paper looks at zero-till residue management on soil health parameters in a maize-chickpea pattern in the black vertisols of India. After 4 years the soil bulk density was reduced by 3.0–10.2% and volumetric moisture content was improved by 10.2–19.3% at 0–10 cm soil depth in ZT with residue over conventional tillage (CT). Organic carbon and labile carbon,  P and K, total fungal and actinomycetes were also increased compared to CT at 0-10 cm soil depths.

This paper looks at the issues of sustainable nitrogen management using no-till practices using a Global Meta-analysis. They used 2,268 pairs of data points from 327 peer-reviewed articles. Increases of 21 and 16% in total N concentration and N stock, respectively, were noted under NT compared to conventional tillage (CT) in the surface soil layer (0–10 cm) but little change below this surface soil. Continental and temperate climates recorded significant gains in total N in NT while the effect was negligible in tropical and dry climates. An incremental rise in soil-N was found with an increase in the duration of NT. No-tillage favoured the soil N and as a consequence, fertilizer-N use under no-till condition, must take into account of the potential N release from SOM for achieving higher N-use efficiency.

This Brazilian study evaluated the long-term effects of soil management systems (SMS) on liming efficiency, soil chemical properties and wheat yield. The study was part of a long-term experiment started in 1986 in Brazil and used data from 2008-2015 with lime added in 2008. There were two CA systems, no-tillage (NT) and reduced tillage (RT) and two CT systems, disk ploughing + disk harrowing and mouldboard ploughing + disk harrowing annually. The NT system was the most sustainable with increases in SOC. After liming, the CT systems were more effective that CA systems in decreasing Al3+ toxicity and increasing soil pH and Ca2+ and Mg2+ concentrations at deeper soil layers. But the NT system had higher wheat yields (+18%). The NT system was the least detrimental to soil organic carbon, an important indicator of soil quality. 

This report from Spain in a semi-arid agro-ecosystem looked at different nutrient sources under minimum tillage. Organic amendments were compared with mineral fertilizes over a 5-year crop rotation using wheat. Wheat yield and biomass, and several soil properties were measured (pH, soil nutrients, soil organic matter  potentially mineralizable nitrogen, total microbial activity and heavy metals) throughout the 10-year study. Wheat yield was better under organic compared to mineral fertilizer. The application of organic amendments under MT resulted in a promising management agro-ecosystem compared to the mineral fertilized because crop nutrients came from organic wastes, no herbicides were applied while the yields were higher.

This paper highlights some of the issues, plus and minus, with CA in South Africa. On the plus side there are benefits in increases in SOM and organic-N in soils. On the negative side, experiments show strong stratification of important plant nutrients (P, K, and Ca) at shallow soil depths due to low mobility in the soil. Results to date have also demonstrated poor root development near the soil surface under the extreme conditions in the marginal cropping areas that dominate most of South Africa’s crop production areas causing lower nutrient uptake in no-till compared to conventional tillage. Poor movement of lime also affects soil acidity. Also maize needs more nitrogen under NT than CT.

This study looks at residue management in CA systems on the black cotton soils (vertisols) of India. Retention of soybean and wheat residues in black soils under a no-till system is important to protect the land from degradation. The main objective of this study was to test the effect of different levels of soybean and wheat residue retention on the physical, chemical, and biological properties of black soil. Four levels of soybean and wheat residue retention (no residue, 30, 60, and 90%) on soil properties was evaluated. Soil organic carbon (C) significantly increased from 0.67 to 1.0% in 5 years through 90% residue retention. Retention of 90% soybean and wheat residues (7.0 and 13.8 t ha, respectively) significantly improved the physical, chemical, and biological properties of black soil in 5 years, therefore protected the soil from degradation.

This is a study of the parasitic weed, Striga, a frequent problem for smallholder farmers in South Africa. They used system dynamic modeling to assess the efficacy of various striga treatments (SCPs) across different seasons and agroecosystems in maize based cropping systems. Model simulations indicate that while a combination of SCPs are necessary to manage the weed, future research should focus on developing smallholder-adapted SCPs that address the attachment stage of the weed's lifecycle (e.g., timely manure application) rather than its germination, emergence or flowering stages. They conclude that it is imperative to develop decision support tools like systems models to evaluate SCPs for smallholders that help extension agents to provide correct information to farmers.

This study in Finland looked at soil physical, chemical and biological properties, erosion and carbon allocation to soil physical fractions between CT and NT at a clay soil site after 10 years. After 10 years various soil properties and earthworm total density, mass and species richness were determined. Total soil erosion was 56 % less in NT than in CT although surface water discharge was higher in NT. NT had a clear effect on the topsoil physical structure by decreasing the pore size and increasing soil aggregate size. This paper didn't mention residue management. The results showed that NT is an effective method to reduce erosion rates but other means to increase carbon input especially below the topsoil layer are likely required to achieve a significant increase in the carbon stock of boreal clay soils.

This study looked at various treatments that affect P availability and P-solubilizing microbes (PSMs) in a 15 year long term, CA agronomic trial in Western Kenya. They selected 8 treatments for comparisons. Reduced tillage significantly (P < 0.05) increased microbial biomass phosphorus (MBP) and abundance of different PSMs relative to conventional tillage, though the results were not consistent for some species. Residue addition significantly increased maize grain yield, MBP and abundance of different PSMs compared to systems without residue addition. Some PSM strains were significantly more abundant in maize and soybean intercropping systems compared to rotation, and vice versa. They conclude that not only the agronomic inputs applied but also tillage and cropping systems employed can variably affect the soil microbial populations.

Increasing climate variability is affecting  smallholder farmers in southern Africa. This study looks at Conservation Agriculture (CA) as a way to improve the resilience of farming systems against the adversities of climate, specifically moisture stress.CA and CT practices are assessed over a 14 year trial period on soil moisture and infiltration rates in Zambia. Soil chemical properties were also evaluated for these two tillage systems. Results showed significant differences in average soil moisture in the first 60 cm among the cropping systems in different years with the basins plus mulching system having highest moisture content in most of the years. Water infiltration rates were highest and averaged 48.5 mm h−1 in the CA-based systems and the lowest in CT which averaged 12.6 mm h−1. Soil chemical properties did not differ across tillage systems. The increased infiltration and available moisture in CA systems can buffer the effects of climate variability and provide greater resilience.

This review assessed the impact of anthropogenic interventions, including crop diversification in rotations, soil physical disturbance, synthetic chemical inputs, and biofertilizer use on soil microbial community structure and function, and the consequential effects on agroecosystem productivity and environmental sustainability from 160 medium- to long-term experiments across the globe and in various soil-climatic zones. Excellent conclusions are made and the study concludes that the key is to establish a rational balance between anthropogenic activities for agroecosystem productivity and potential negative influences on the soil microbial community and long-term soil health.

This study aimed to evaluate the long-term (23-yrs) effect of soil tillage systems and winter cover crops on (i) soil acidity, (ii) nutrient availability, and (iii) P and K budget in a subtropical Oxisol from Southern Brazil.They used 6 cover crops and CT vs NT. Continuous NT system for 23-years resulted in higher soil fertility in the topsoil (0–10cm) compared to CT, but with some limitations of nutrient availability and soil acidity below 10cm depth compared to CT. Surface application of lime in NT reduced soil acidity up to 20cm compared to CT. The budget of P was negative for all treatments, highlighting the P-sink behavior of this strongly weathered subtropical Oxisol. Among the cover crops tested, black oat stood out by its greater production of biomass, resulting in higher P and K availability in the soil surface.

Climate change is causing declining rainfall (more variability) and increasing temperature extremes and when added to declining soil fertility, food security in rainfed Morocco is threatened. The objective of this study was to systematically evaluate agronomic, economic, and soil fertility indicators under CA and conventional tillage (CT) using field experimentation (medium-term) and simulation modeling (long-term) for a clay soil in Morocco. They looked at the effect of CA on wheat, barley, lentil and chickpea to determine yield, stability, profits, WUE, and soil fertility. They also used Dynamic simulation modeling to assess the long-term effect of adopting CA and CT in these cereal rotations. Both their 5-year field experiment and the modeling showed that adoption of CA improves a range of agronomic, economic and soil fertility indicators compared to CT.

This study looked at ways to replenish declining soil fertility. It evaluated pH, EC, Exchangeable cations, microbial biomass carbon, total N and C in a CA system. This study had three crop rotations, and 3 residue treatments; residue retention, removal, and biochar amendment. Soil pH and EC were not affected by these practices after 3 years. Magnesium and potassium were significantly affected by tillage at 0–5 cm depth. At the end of three years, CA resulted in net increases of total N, and C, and MBC compared to conventional practices.

This study from Poland looks at various cover crops and two tillage systems, plough tillage (PT) and no-tiillage (NT) on spring wheat grain. All the cover crops tested in this study contributed to an improvement in the chemical composition of the soil used in the experiment (a significant increase in humus, P and Mg content). Both the cover crops and the conservation (no-tillage) system stimulated the activity of soil enzymes: dehydrogenase and urease. The highest content of all the macro- and micronutrients analyzed in wheat grain was found in the cover crop treatments. Spring wheat responded favorably to the reduced tillage system (no-tillage).

This study from China looked at long-term straw mulching under a no-till system  on soil physicochemical and biological properties at different soil depths (0-30 cm in 10cm increments) in a no-till rice-wheat system. Straw was removed (CK) or mulched (SM) in this 12-year study. Organic carbon, nutrients, and bacterial abundance were reduced by depth, but pH increased. SM significantly increased total N, inorganic N, available P, available potassium, and soil water content at 0-5 cm, total organic C content at 0-10 cm, and dissolved organic C and N contents at 0-20 cm compared to CK. The study also reports data on the effect of SM vs CK on various bacterial groups. Overall, they conclude that the SM treatment is highly recommended under a no-till system because of its benefits to soil fertility and bacterial abundance.

This paper looks at the conversion of land use for paddy rice to oilseed rape to vegetables on land degradation in China based on soil chemical properties measure by soil analysis and farmer interviews.  In the vegetable cropping system, fertilizer application often exceeds the crop demand or levels recommended that lowers crop use efficiency for nutrients. In the vegetable cropping system studied, SOC, C stock, TN, and N stock were decreased significantly due to low organic inputs from crop residues and high tillage frequency. They conclude that use of CA practices and integrated soil-crop management help recover degraded soils and improve vegetable productivity.

This chapter looks at the role and spread of CA on SOM that is vital for soil biological, physical, chemical and hydrological properties that also helps soil retain and release nutrients and water for crop growth. It contends that mechanical disturbance of soil by tillage agriculture is one of the most serious environmental consequences that results in SOM decomposition, mineralization and C02 emissions.

This study investigated the response of soil chemical, biological and bacterial community properties to 11 years of different mulch and tillage practices in a sandy soil in a continuous maize cropping system in China. Treatments included: no-till + residue (ZT+R), rotary tillage + residue (RT+R), and normal tillage (CT). Compared to CT, ZT+R and RT+R significantly increased total organic carbon (TOC) content, C:N ratio, available nitrogen (AN) content, and acid phosphatase (ACP) and urease activities, while decreasing soil pH in topsoil and subsoil. ZT+R increased bacterial richness and diversity; dominant phyla of Actinobacteria and Acidobacteria were found in topsoil and Gemmatimonadetes in subsoil and deep soil. However, RT+R showed negative effects on soil bacterial diversity and bacterial community because of severe soil disturbance. ZT+R was the best treatment for chemical and biological properties in these sandy soils.

This paper evaluated the chemical and physical processes in two different agricultural soils under no-tillage and conventional management practices to determine their impact on water related soil functions at field scale in the United Kingdom.Two farms were monitored; one had used NT in 2013 and the other conventional tillage with MB plow. Two soils were evaluated under each farming practice over two years. The conversion to no-tillage changed the soil structure, leading to a higher bulk density and soil organic matter content and thereby increasing the soil moisture levels. These changes impacted the denitrification rates, reducing the soil nitrate (NO3) levels. The increased plant material cover under no-tillage increased the levels of soil phosphate (PO43-) and PO43- leaching. 

This paper applied two independent soil health assessment approaches to evaluate the impacts of 40-yr conservation tillage (CST) and additional 4-yr cover cropping on a range of soil health indicators and the overall soil health in typical southeastern Coastal Plain soils of the USA. The Soil Management Assessment Framework (SMAF) and Cornell's Comprehensive Assessment of Soil Health (CASH) were used to calculate soil health indices. When compared to conventional tillage, 40-yr CST increased active carbon (C) from 301 to 420 mg kg–1 and organic nitrogen (N) mineralization potentials from 0.78 to 0.91 mg kg–1 d–1, but it reduced soil electrical conductivity from 133 to 101 μs cm–1. No difference in soil aggregate stability, total C, extractable phosphorous and potassium, microbial biomass C, respiration, and glucosidase activities were observed between the two tillage treatments. Increasing organic inputs along with CST is seemingly the optimal management option.

This paper looked at P fractions where long term (40 year) CA and residue return and 4 year integration of cover cropping that improved soil organic matter. Conservation tillage increased KCl-extractable inorganic P (KCl-Pi) stocks in top soils (0-5 cm) when compared to conventional tillage, but had no effects on other pools at both 0-5 and 5-15 cm depths. Cover cropping caused significant accumulations of NaOH-extractable organic P (NaOH-Po) in top soils (0-5 cm). Neither conservation tillage nor cover crop changed the contributions of the chemically defined pools to soil total P.  Conservation tillage improved P availability potentially through its effects on microbial activities, whereas cover cropping increased P stocks and availability by promoting Po accumulations.

This Brazilian study looked at water retention in relation to soil physical and chemical properties on Cambisols with different land uses in a semi-arid region of Brazil.  The environments studied were Preserved Forest - reference area, Cajarana Orchard Area, Corn/Bean Consortium, Watermelon/Pumpkin Consortium, and Agroecological Cultivation. The Preserved Forest presented the highest field capacity, permanent wilting point, and available water. The study concluded that the soil tillage systems alter the chemical, physical and structural attributes of Cambisols of the semiarid area studied and that minimum tillage is the most suitable tillage system for the region.

The UK launched a program to evaluate the extent to which on-farm mitigation measures can cost-effectively reduce the impacts of agricultural water pollution on river ecology whilst maintaining food production capacity. This study looked at the impacts on soil health of two types of conservation tillage (direct drill and shallow non-inversion) against conventional mouldboard ploughing after five years. Results revealed that conservation tillage alone is ineffective at improving the short-term environmental sustainability of farming practices in this lowland intensive arable setting and indicates that a broader, integrated approach to conservation agriculture is required incorporating aspects of cover cropping, crop rotations and precision farming techniques. The improvements in farm business performance do, however, demonstrate land managers can make important financial gains by converting to a conservation tillage system.