Conservation Agriculture Research Updates - March 2026

This study looks at the benefits of CA practices over nine years in Malawi with maize and maize intercropped with groundnut. The treatments were farmer practice (FP), Pit planting+mulch (PPM), intercropping+mulch (INM)and mulching (MC). Maize yields were higher with CA practices than FP (4.0-4.4 vs 1.8 t/ha) and also improved soil properties. The land equivalent ratio for maize and groundnut intercropping in INM was 1.77, indicating beneficial intercropping efficiency. They conclude that CA interventions contribute to increased crop yield, income, and soil fertility restoration in the agricultural land but farmer adoption will depend on the farmer's intention.

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.

Soils under NT in Brazil have been chiseled to correct compaction. This paper hypothesizes that use of crops with deep roots in the rotation could be an alternative to mechanical chiseling. The objective in this study was to evaluate changes in SOC stocks, root development, and crop yield over time caused by mechanical and biological chiseling in a long-term no-till system (18 years). The treatments were 1) No-till cover crop (NT-CC). 2) No-till Mechanical Chiseling (NT-MC) and 3) No-till Biological Chiseling (NT-BC). Compared to NT-CC, the use of NT-MC depleted the SOC stocks by -0.41 Mg ha−1 year−1 and raises concerns about this practice. NT-MC also depleted proxies for microbial- related C pools such as hot-water and permanganate extractable C. However, the results demonstrated that the use of radish as an intercrop for alleviating soil compaction was a good alternative to replace mechanical chiseling in compacted NT fields due to its superior performance in increasing SOC stocks, promoting higher root development, and crop yield.

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 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 reports on the effect of cover crops on modifying soil surface response to penetration and the relation to soil water content. The research used two crops, barley and vetch, as cover crops and compared them with a bare fallow in a 10 year long term trial in Spain. The soil resistance to penetration was closely related to the surface soil water content (R2 = 0.65) and cover crops affected it through soil moisture modification. The greater biomass of barley compared to vetch increased the soil water content prior to main crop seeding and reduced the resistance to penetration. The good performance of barley resulted in a reduction of more than 60% of the soil resistance to penetration between the 3rd and 8th year of the experiment. Even under bare fallow, soil strength was decreased after ten years with reduced tillage. The maintenance of cover crop residues over surface soil together with reduced tillage enhanced the soil surface conditions and steadily reduced the risk of crust formation.

This study evaluates the climate resilience in terms of profitability and risk management that determine farm-level adaptation. This 27 year long-term study looked at three agricultural treatments. for a corn-soybean-wheat rotation in Michigan. The three alternative treatments were no-till, reduced input and certified organic that were compared with conventional practices for the same rotation. Results demonstrate that the net revenues from the organic treatment are exceed the net revenues of conventional treatment. The no-till treatment dominates conventional and reduced input practices in annual net revenues with a relatively lower risk to those revenues in light of climate extremes. They concluded the organic and no-till treatments were deemed climate-resilient whereas the conventional and reduced input treatments did not show resilience will be vulnerable to the changing climate. But growers have been slow to adopt the two climate resilient practices and this needs further study.

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 is a corrected manuscript for this article that looks at crop diversification and intercropping in CA systems that have a direct impact on nutritional status of farm households due to a more diverse diet. This study from 2012-2020 assesses how the integration of grain legumes, cowpeas and soybeans, in maize-based CA systems either as intercrops or rotational crops affects maize grain yield and stability, total energy yield, protein yield and surplus calories after satisfying the daily requirement per household. Results show that intercropping compromises maize yields with marginal yield penalties of −5% compared to no-till monocropping. However, intercropped yields were more stable across environments.Total system caloric energy and protein yield were highest in intercropping systems due to higher productivity per unit land area owing to the additive contribution of both maize and legumes. 

This study looked at how long-term no-tillage with different amounts of maize residue retention affect microbial community composition and soil microbial communities and soil-borne plant pathogen abundances. No-tillage with residue retention significantly increased fungal richness but had little effect on bacterial diversity. Relative abundances of some fungal and bacterial genera changed significantly under no-tillage and residue treatments, with the greatest change found in the 33% mulching treatment. Furthermore, no-tillage with 33% and 100% mulching had the greatest effect on F. graminearum and F. moniliforme abundances. 

This long-term study used analysis of 10 years of data to look at the effects of variation in seasons between treatments on yield of maize. There was a strong treatment effect between rotational treatments and other treatments and a weak effect between intercropping and monocropping. There was no evidence for an overall advantage of systems where residues are retained (in combination with direct seeding or planting basins) over conventional management with respect to maize yield. Also showed that significant treatment effects are unlikely with just 4 replicates and suggest designing trials that have less treatments and more replicates.

This paper from Eastern India looks at various ways of establishment of crops in a rice-pulse system and their effect on cellulolytic bacteria. . It has 7 different establishment systems that include the traditional puddling and transplanting for rice but also direct seeding with inter-cropped Sesbania, wet direct sowing, ZT direct sowing and use of drum seeder plus biochar. Their findings show that long-term ZT in the rice-pulse system could be a unique source for efficient cellulose decomposing bacteria and further the efficient bacterial strains isolated from this system can be used as efficient bioinoculants for in situ as well as ex-situ decomposition of rice straw particularly in conservation agriculture

This study investigated the effects of CA and CT on soil organic carbon (SOC)and selected hydraulic properties in two contrasting areas in Malawi using on-farm trials. Sole maize with CA and CT plus maize-legume intercropping with CA were used. Soil samples were taken after using CA for 10 years at 6 different depths. At all sites CA improved total SOC, carbon stocks and stable fraction of of particulate organic carbon. They conclude that changing management practices from CT-SM to CA has the potential to improve the soil organic matter and soil hydraulic properties across agro-ecological zones in Malawi.

This long term study in Italy looked at the combined effects of the tillage system and crop sequence on SOC and biochemical properties associated with improved soil health. After 23 years of CT and NT, with continuous wheat vs a wheat-faba bean rotation soil samples were taken from 0-15 and 15-30 cm at three times during the year. Long-term NT increased total organic C (TOC) at a yearly rate of 0.17 g kg−1. This in turn stimulated microbial biomass, in particular Gram-negative bacteria. No differences were observed with regard to fungal biomass. Long-term NT varied widely by crop sequence, whereas in CT changes in biochemical characteristics and in the main microbial groups due to crop sequence were modest.

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%).

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.

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.

This 16 year long term study in Hungary looked at the effect of conservation tillage (CT) on run-off, soil loss and soil in large plots and compared with ploughing tillage (PT). By the end of the study period, significantly higher water-stable aggregates (PT: 20.0 %, CT: 30.4 %), higher soil organic matter (PT: 1.4 %, CT: 1.9 %), greater earthworm abundance (4.9 times that in PT plots) was recorded on the CT plots. The difference between PT and CT was significant for mean annual soil erosion, with values of 2.8 t ha−1 and 0.2 t ha-1, respectively. They conclude that the use of CT enabled the maintenance of a major fraction of precipitation on arable land, and consequently, soil loss remained an order of magnitude lower than its tolerable value.

In this paper, a process-based model, Denitrification-Decomposition (DNDC), was validated on midterm (9 years) and employed depending on the local climate, soil and management conditions, to assess the impacts of alternative management practices on SOC stock under two tillage systems, in a semi-arid region of Morocco. Modeled results pointed out that, under no-tillage practice (NT), the SOC content increased by 30% compared to conventional tillage (CT). During the simulated period (9 years), the SOC sequestration potential (CSP) has been greatly improved with increased crop residue rate and application of farmyard manure (FY-manure). They conclude that an increase in crop residue rate returned at surface after harvest and application of organic fertilizer, especially under NT practice, can substantially improve SOC stock in a semi-arid region.

This is an interesting paper from Cambodia looking at nematode issues in lowland rice managed using CA. They compared nematode populations, rice yield and soil organic matter in conservation agriculture management, conventional rice systems with greenmanure management (GMCT) and conventional plough-based tillage systems. Results demonstrated that GMCT for one year (GMCT1) and the long-term CA for seven years (CA7) reduced nematode densities in both soil and in rice roots, almost throughout the study period, compared to the CT system. For rice yield components and soil fertility, CA7 proved to be effective in increasing plant height, the number of tillers/plant and soil organic matter.

This study estimates the statistical effect of Conservation Agriculture on cropping-system yields (as opposed to single crops) under historical climate conditions. The cropping-system yields considered all crops grown including maize (Zea mays L.) and legumes in intercropping or rotation, or both. Data included 6296 yield observations from on-farm trials in farmer plots conducted over 14 seasons. This work studied three treatments: (1) a Control Practice treatment where the soil was tilled, crop residues were removed, and there was no crop species diversification, (2) a NT treatment where the soil was not tilled, crop residues were retained, and there was no crop species diversification, and (3) a CA treatment where the soil was not tilled, crop residues were retained, and there was crop species diversification through legume intercropping. The results demonstrate how CA can improve the adaptive capacity of cropping systems and this provides urgently needed evidence on how farmers can adapt to climate stress.

The question whether NT systems are as productive as those relying on conventional tillage (CT) is a controversial issue, fraught by a high variability over time and space. This study expands existing datasets to include the results of the most recent field experiments, and we produce a global dataset comparing the crop yields obtained under CT and NT systems. In addition to crop yield, this dataset also reports information on crop growing season, management practices, soil characteristics and key climate parameters throughout the experimental year. The final dataset contains 4403 paired yield observations between 1980 and 2017 for eight major staple crops in 50 countries. The paper does discuss the results for NT versus CA, since the residue retention in the latter is important for success in some but not all situations and crops.

This study assessed the impact of long-term conservation tillage and N fertilization in wheat-soybean rotation on soil aggregate distribution, nutrients stocks and functions of soil microorganisms. They compared conventional tillage and minimal tillage and 2 N levels; 0 and 200kgN/ha. Residues were incorporated to 25 cm in CT and 50% to 15cm in MT. Tillage was the most discriminant factor explaining 72% and 60% of total variance of soil parameters at 0-15 cm and 15-30 cm soil depth. All enzyme activities were higher under MT, whereas the majority of soil chemical parameters were higher under N200. They conclude that maintaining or even increasing SOC conservation in their silt loam soils may require both reduced tillage systems and N fertilization, shifting microbial community toward taxa more effective in contrasting soil degradation

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.

This paper uses a long-term continuous maize experiment to understand water and nitrate-N functions under no-tillage with mulching in dryland farming in China. It reports data for a complete year for spring maize plus the fallow period after 15 years of continuous maize. Treatments included conventional tillage (CT), no-tillage (NT), no-tillage with biochar (NB), no-tillage with straw mulching (NS), no-tillage with plastic film mulching (NP), and no-tillage with straw-plastic film mulching (NSP). Average soil profile water content (SWC) and the soil water storage (SWS) of the mulching treatments  were higher than the non-mulching at each stage. The study did show that mulching is required with NT and just NT may have lower yields. The plastic mulch was the best treatments in their research.