Conservation Agriculture Research Updates - April 2026

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 study looked at various conservation management practices -- agroforestry, cover cropping, no-till, reduced tillage, and residue return on surface runoff and erosion. Most of the data were collected from China, USA, Europe, and Africa. They compared production with and without these CMP's. They explored interactions between CMP practice type, soil texture, surface runoff, and soil erosion. They then related changes in surface runoff and soil erosion to 13 other soil health and agronomic indicators, including soil organic carbon, soil aggregation, infiltration, porosity, subsurface leaching, and cash crop yield. They found that across all CMP's, surface runoff and erosion had respective mean decreases of 67% and 80% compared with controls. Cover cropping provided the largest decreases in erosion and surface runoff, thus emphasizing the importance of maintaining continuous vegetative cover on soils. 

This study estimated the the spatial-temporal variations of maize yields from 13-year on-farm trials from 4 countries in Southern Africa. Agronomic data from long-term CA trials is used with gridded biophysical and socioeconomic variables. Comparisons were made between CA and CT practices with above and below average precipitation. The variable importance analysis showed that the altitude, precipitation, temperature, and soil physical and nutrients conditions variables explained most of the variation in maize grain yield. Maps were generated to identify the locations where CA had a yield advantage over CP during seasons with below and above-average precipitation. The paper concludes that multi-source remotely sensed data, coupled with advanced and efficient machine learning algorithms provides accurate, cost-effective, and timely platforms for predicting the optimal locations for upscaling sustainable agricultural technologies. 

This 3-year study was undertaken in northern Italy. Bulk density (BD), penetration resistance (PR), soil hydraulic saturated conductivity, and sorptivity were used to evaluate soil quality obtained by combining three tillage intensities (conventional tillage – CT; minimum tillage – MT; no tillage – NT) with three winter soil coverings (bare soil – BS; tillage radish cover crop – TR; winter wheat cover crop – WW). Reduced tillage coupled with WW improved soil physical properties even below the tilled layer, as evidenced by root-growth-limiting condition reductions. They conclude that, despite the increase in BD and PR due to reduced tillage, the strategy improved soil functioning and particularly soil hydraulic conductivity. In the short term, the WW cover crop moderately increased physical soil parameters, whereas TR had negligible effects. This study demonstrates that, to quantify CA, several soil physical parameters should be monitored.

This paper reports on the eukaryotic community diversity in small  (sM) and occluded micro-aggregates (mM) following 23 years of reduced versus conventional tillage and 0 and 200 kg of nitrogen in a wheat soybean rotation. They found a different eukaryote diversity response to management intensification across soil aggregates and soil depths; (ii) a conserved core community composition of eukaryotes across CA treatments and aggregates at surface and subsurface layers; (iii) a different effect of tillage on eukaryotic community structure in sM and mM along the soil profile according to N availability; (iv) a positive association of protists, and fungi with the amount of sM and mM, and their SOC content; (v) a stronger complexity of within- and cross-domain networks (eukaryotes and eukaryotes-prokaryotes) in mM than in sM at surface layer.

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 tested the hypothesis that CA has contributed to the sustainability of Brazilian soybean production with positive effects on soil quality, grain yield and nutritional quality and growers profitability. They conclude that CA enhanced carbon sequestration, physical and especially biological quality of soil, which caused improved soybean grains yield, protein and flavonoids content and profit. This compares with the traditional annual soybean and maize double crop (Zea mays), that reduced soil physical quality with impacts on food security and agricultural sustainability. Sustainability of Brazilian soybean production can be increased by inserting crop rotations involving cover crops in the rotation cycle.

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 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 meta-analysis reviewed experimental results (32 field studies) obtained throughout the Pampas Region in Argentina focused on the immediate effects and duration of soil mechanical alleviation measured by relevant soil physical properties and by the impact on maize and soybean yield. Treatments were a) Control (no tilled soils), and b) Subsoiled (no tilled soil subjected to mechanical compaction alleviation by deep non-inversion tillage). Soil compaction alleviation works had a durability of not more than 17 months (±2.8 months) after being performed. They conclude that deep non-inversion tillage could be a promising practice to close rainfed crop yield gaps in the region. But due to its low durability in time, further compaction prevention and structural regeneration practices such as cover crops, diversified crop rotations and controlled traffic will be needed

This study looks at the data from a long-term trial in Eastern India with 4 treatments: Traditional rice-wheat (TA), Full CA (fCA), and two partial CA's, pCA1 and pCA2 that differ in crop establishment methods, cropping system and crop residue management. Soil health parameters were measured in the 11th year of the experiment. The results revealed a beneficial effect of CA and 46 and 40% increase in SOC concentration and stock, respectively, under fCA over TA in the 0–7.5-cm soil layer. The effect of partial CA (pCA1 and pCA2) was variable, but an increasing trend was always observed under pCA compared to TA. The yield of rice in CA was comparable to or higher than in TA, whereas the system rice equivalent yield was always higher (38–53%) under CA than under the conventional practices. They conclude that CA can be promoted for sustainability of a rice–wheat system due to higher productivity (38–53%).

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 study looked at the physical attributes and organic carbon contents of a clayey Oxisol in an area under four different land uses for 10 years: afforestation (AF), no-tillage system with grass-grass succession (corn/corn), no-tillage systems with grass-legume succession (corn/Crotalaria juncea L.) and conventional soil tillage system (corn/fallow in Brazil. The areas were sampled at 3 different depths and evaluated for soil aggregation and porosity using multivariate factor analysis. The no-tillage system promoted soil aggregation and porosity similar to that of the planted forest and superior to those of the conventional tillage system. The type of crop succession in the no-tillage system caused differences in soil structure, and grass-grass succession (corn/corn) promoted better soil structure compared to other systems. The greater soil porosity generated by the conventional tillage system was limited to the most superficial layer but the presence of large amounts of smaller aggregates can clog the generated pores.

This paper reviews 34 papers that illustrate ZT can influence porosity depending on soil texture, pore size class, depth and time, and also influence important transport mechanisms likely to impact the fate of agrochemicals in soils. They suggest the value of a prospective examination of an evolving ZT pore network both visually and functionally across temporal and spatial scales. They also highlight the necessity for standardised methodology to aid in future data compatibility and quantitative analysis.

This Meta data analysis showed that NT significantly improved mean weight diameter (MWD) and field capacity moisture content by 19-58% and 6-16%, respectively, and resulted in no significant change in bulk density (BD), but infiltration rate increased by 66%. CA improves SOC stocks by addition of more C inputs through greater biomass production and reduction in SOC losses due to surface soil cover and locking SOC in soil aggregates. This causes net sequestration of atmospheric C into the soil, leading to climate change mitigation. Findings of a majority of studies suggest that CA can be a potential alternative to the conventional agricultural practices for managing soil health and improving soil C stock, and thereby sustaining productivity and mitigate climate change.

A field experiment and meta-analysis was used by the Chinese study to look at the effects on no-tillage on wet stability of aggregates (WSA), clay dispersibility (ClayDis), mean weight diameter (MWD), and aggregate SOC distribution and mineralization in rice paddies. Four tillage practices: no-tillage, rotary tillage and moldboard plow tillage with rice straw retention (NTS, RTS and CTS respectively), and moldboard plow tillage with rice straw removal (CT). Additionally, the meta-analysis showed that no-tillage increased the macroaggregate content, WSA and MWD. They conclude that In rice paddies, the increased macroaggregate content may contribute to increasing SOC, which improves soil structural stability (SSS) under 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 is another paper from the SSSA special section on CA. This study aimed to assess the effects of land use, tillage management, and crop diversification on soil physical quality of two long-term experiments in the Cerrado of Brazil through on-farm visual evaluation of soil structure (VESS) and soil physical parameters. Soil sampling was performed in 0-to-10- and 10-to-20-cm layers of four agricultural systems: soybean [Glycine max (L.) Merr.]–fallow under conventional tillage (SF); soybean–fallow under no-till (SN); soybean–maize (Zea mays L.) succession under no-till (SM); and crop rotation under no-till including soybean, maize, grasses, and legumes (CR). Native vegetation was kept as a check (NV). The study highlights that intensified agricultural systems need to be coupled with strategies to reduce and/or control intensive machinery traffic.

This study evaluated in the short-term (7 months) the dynamics of several abiotic and biotic soil parameters under contrasting tillage systems in France. Three tillage systems were investigated: conventional tillage (with the soil inverted up to 25 cm depth) reduced tillage (limited to the first 7–8 cm depth) and no-tillage. Collembola and earthworms were sampled at each plot using standard methods. Abiotic parameters (bulk density, SOC stock, Mean Weight Diameter (MWD) and aggregates size) and microflora (microbial and fungal biomass and their activity) were also monitored and used as explaining factors. They conclude that overall, conservation tillage can foster one of the numerous services provided by the soil compartment, namely the soil biodiversity and therefore improve soil quality and health.

Soil compaction is a main issue threatening soil function and quality. This paper evaluates tillage and wheeling effects on physical properties of soils. The treatments were 13 years of no-tillage (NT), NT compacted with additional wheeling (NTc), minimum tillage (chiselling) soil (MT), and MT compacted with additional wheeling (MTc). Soil bulk density (Bd), macroporosity (Mp), precompression stress (sigma p), compressibility coefficient (Cc), and relative deformation were determined in four soil layers. Surface compaction in conservation agriculture is a major issue, since soil mobilisation by soil tillage should be avoided. Adding the residue mulch component of CA would have been an interesting additional treatment since other studies have shown that NT and mulch is better than just NT.

This article was chosen since it studies tillage systems and liming in a sugarcane system in Brazil. Infiltration tests and soil sampling down to 0.10 m were performed in order to determine saturated soil hydraulic conductivity, soil bulk density, soil total porosity, macroporosity, microporosity, and soil resistance to penetration. Treatments included no-tillage (NT) and conventional tillage (CT) with 0 and 4 t/ha lime and an adjacent native forest (NF) as a check. The lowest bulk density and highest soil total porosity, macroporosity and saturated hydraulic conductivity were found in the NF. The bulk density in CT4 and NT0 was higher than in other systems, indicating the need for amelioration. NT4 is suggested as the most viable system for conservation agriculture in sugarcane fields, combining the benefits of no-tillage and liming to enhance soil hydrophysical functions.

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 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 looks at the concept of biological tillage that they define as "improving soil structure with plant roots". They use cover crops with thick and deep roots planted timely and using a roller-crimper to eliminate them later on. An effective bio-tillage cover crop should have thick and deep roots with rapid root growth rates, rapid decomposition of remnant roots, and good adaption to climate and soil constraints. More research is needed on biotillage in a CA situation.

This study was evaluated the effect of conservation tillage practices in a maize-wheat cropping system on near-saturated soil hydraulic properties and pore characteristics.There were three tillage treatments - CT, Minimum Tillage (MT) and ZT - were evaluated after 7 years of each tillage treatment . Results revealed significantly (p < 0.05) higher values of ks, k(h), α, and Ɛ in ZT as compared with CT. MT had intermediate values. Overall, zero-tillage based agriculture system was found to improve near-saturated soil hydraulic properties.