Conservation Agriculture Research Updates - March 2026

This is another paper that studies the effect of rotation under NT in Australia on key soil constituents where herbicide resistant weeds are controlled by windrow burning. This 12 year study looked at rotation diversity and residue management on soil nutrients. 5 rotations were selected and 2 residue treatments; left on the surface or burnt in windrows before seeding. By the end of the experiment, soil organic carbon stocks (0–30 cm) were significantly lower in the farmer rotation compared with the cereal and diverse rotations. There was no significant difference between the cereal and diverse rotations. The annual burning of windrows for weed seed control was found to reduce soil organic carbon stocks.

This paper looks at barley and maize in Mexico's major growing area for barley where barley is irrigated followed by rainfed maize. Groundlevel water levels are declining in this area and water saving technologies are needed in this area. This study looked at water use and grain yields with CT and CA with furrow and drip irrigation in 3 year experiment and in adjacent farmer fields. Results show water use reductions differed strongly between years, depending on weather. The water saving through conservation agriculture in farmers' fields was similar to the water saving in the controlled experiment with about 17%. Farmer's fields conservation agriculture also reduced greenhouse gas emissions by 192 kg CO2/ha and improved soil health.

This chapter 11 in the book listed above is devoted to CA in rice-wheat areas of South Asia. This geographic area is challenged to feed almost 2.5 billion people while the resource base is being degraded and climate change is causing significant problems. CA is being promoted as a management system to combat some of the challenges arising from previous intensive tillage systems. Much work has been done on the rice-wheat systems with CA management. Recently, these practices have also been applied to other crops and systems in South Asia with encouraging results. This chapter describes some of these successes.

This paper looks at micro-economic evidence of the welfare effects of CA using recent panel data from Ethiopia combined with novel historical weather data. They use a panel data endogenous switching regression model to deal with selection bias and farmer heterogeneity in CA choice. The study finds that the CA practices that play a pivotal role in addressing the exigencies of rural poverty are minimum tillage, cereal-legume intercropping, and their combination. These practices reduce the incidence and depth of poverty in areas prone to rainfall stress, which is an indication of their risk mitigation role. They caution against exaggerated expectations of CA's economic benefits and a rigid recommendation of CA.

This study aimed to quantify the effect of tillage, crop rotation and crop residue management on aggregate stability, binding agents and the resulting aggregate microstructure in a sweet sorghum-based cropping system in a low organic carbon soil. Two tillage levels; no-till (NT) and conventional tillage (CT), two crop rotations, i.e., sweet sorghum-grazing vetch-sweet sorghum (S-V-S) and sweet sorghum-fallow-sweet sorghum (S-F-S) and three crop residue retention levels, i.e., 0%, 15 % and 30 % were tested. The study showed that tillage is the main factor that influences soil aggregation followed by residue management. The study also demonstrated that aggregate stability is linked to aggregate microstructure and regular pores are dominated in degraded soils with low SOC.

This study evaluated the impacts of CA on crop yield and profitability over 6 years in Ethiopia using a barley-wheat rotation. They compared permanent and semi-permanent raised beds versus conventional tillage. Both bed planting treatments out yielded CT plots every year and provided the highest marginal rate of return.

This paper looks at sustainable and appropriate practices for sweet sorghum smallholder farmers in South Africa and their affect on microbial biomass carbon (MBC) and enzymes. They compare CT with NT, various rotations and residue management. Tillage x rotation x residue interactions influenced MBC. They conclude that Soil biological indicators were higher under NT and 30% residue retention respectively. NT + sorghum-vetch-sorghum rotation +30% residue was a better treatment combination to enhance soil quality under bioenergy sweet sorghum in South African marginal soils.

This paper from ICARDA looks at the performance of various crop genotypes under CA and look at the tillage by Genotype interaction and effects on yield of barley, chickpea, lentil, and wheat. Thirteen elite genotypes for each crop were planted under both CA and CT systems. They conclude that varieties with wider adaptability to drought, higher yield stability, and adoption of CA practices may be more efficient than developing breeding programs for each type of tillage system.

This 13-year study in India looked at soil properties and the fate of Pendimethalin herbicide in a CA and intensively tillage managed system. Two cropping systems were mungbean-wheat and sorghum-wheat. There were three tillage treatments -- ZT+residue in both seasons; CT in summer + ZT+residue in winter; and CT in both seasons. The adoption of ZT-ZT system resulted in a 24% increase in infiltration rate, 13% greater moisture retention and 69% higher organic carbon content in surface (0-0.05 m) soil over CT-CT. Under the CT-ZT treatment, only a small change in the above soil properties was observed, which indicated that the benefits associated with CA was lost with tillage in the subsequent season. ZT-ZT caused more herbicide leaching into the sub-surface soil.

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 used the ARMOSA process-based crop model to simulate the contribution of different CA components to soil organic carbon stocks sequestration at 0-30 cm depth compared to conventional in three different regions (Central Asia, N and S Europe). Simulations looked at current and future climate conditions.  Five cropping systems were used. The paper concludes the simultaneous adoption of all the three CA principles becomes more and more relevant in order to accomplish soil C sequestration as an urgent action to combat climate change and to ensure food security.