Conservation Agriculture Research Updates - April 2026

This report from CIMMYT, Mexico looked at yield and economics of wheat and maize in a 21 year old experiment comparing these two crops on conventional tilled beds to permanent beds with varying residue levels. They also added tied ridges in the furrows to see if they could offset the negative effects of removal or crop residues. Permanent bed planting (PBP+R) plus residue showed better yields compared to the CT beds. PBP plus full residue also yielded better than partial residue but partial residue with tied ridges had equal yields to PBP plus full residue. But treatments with partial residue and tied ridges results in higher net returns because of the value of residue for animal feed, although this is contingent on the market for residues. 

This paper studies the effects of no-till (NT) and residue over the long- and short-term (24 and 3 years) in a semi-arid area of Mexico in a maize-oat-triticale system established in 1995. There were 6 treatments: plow+harrow (PH), harrow (H), multi-plow (MP), No-till (NT), NT with 33% residue, and NT with 66% residue. Soil quality was increased with NT + R by increasing SOM but also total carbon and enhanced microbial abundance. Tillage treatments, however led to lower SOM and lower yields. Differences were also visible soon after the experiment was initiated.

This interesting article develops a conservation agriculture appraisal index (CAAI) as a standardized conceptual framework with defined thresholds that indicates the intensity and frequency of use of each CA core principle. This index was then applied to 100 farms in 4 wheat growing regions, with and without livestock and including rainfed and irrigated systems in Australia and Mexico to quantify CA adoption. CAAI score is the sum of the scores of each core principle, accounting for the percentage of the farm area and cropping season where CA is applied based on semi-structured interviews, questionnaires, and farm visits. Results show higher adoption in Australia than Mexico. No adoption of CA occurred when one of the core principles consistently scored zero within a year.

Low yields are often related to variable rainfall in semi-arid regions under conventional farming. This paper from the highlands of Mexico evaluates CA in 2 sites on-farm experiments and 17 farmer fields from 2013-2020 to assess yields and profits. Maize grown conventionally on the flat (CT) was compared with maize on permanent beds with residue mulch. The latter plots had monocrop maize and three rotations with either triticale, oats, or common beans. Results showed that average maize yields on beds exceeded CT maize by 70% in one location. Whereas in a second location there was no difference in maize yields between CT and CA systems. On the farmer fields, bed planting was 70% better then the CT. The most profitable rotation was maize-beans in farmer fields and the 2 on-farm trails.

This paper looks at 14 bread and 13 durum wheat varieties for yield and agronomic performance under different tillage and irrigation treatments. The authors suggest that genotype × tillage effects on yield are not well understood and it is unclear whether tillage should be an evaluation factor in breeding programs. The treatments used were conventional and permanent raised beds (no-till on beds) with full and reduced irrigation. Data was collected on an array of different traits including days to emergence, flowering, maturity and various harvest traits. Six years of data of 26 genotypes were published along with the Honsdorf et al. (2018) paper in Field Crops Research (DOI: s10.1016/j.fcr.2017.11.011). This updated dataset includes three additional seasons of data (harvest years 2016 to 2018) and an additional bread wheat genotype (Borlaug100).

Weeds are a major constraint in Maize in Mexico but best management methods are lacking.  This study evaluated weed dynamics and rainfed maize yield under five weed management treatments (pre-emergence herbicide, post-emergence herbicide, pre-emergence + post-emergence herbicide, manual weed control, and no control) and three tillage methods (conventional, minimum and zero tillage) in 3 agro-ecologies in Mexico. The most effective weed management treatments tended to be similar for the three tillage systems at each site, although weed pressure and the potential yield reduction by weeds tended to be higher under zero tillage than minimum or conventional tillage. No single best option for weed management was found across sites or tillage systems.

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 study in Mexico where CA is often been used on permanent raised beds (PB) not tilled, evaluated how PB widths in wheat, maize, and barley. The study selected 9 sites where 6 were rainfed and 3 irrigated. They found that bed width did not affect crop yield. Therefore, farmers can choose the width suitable for their conditions. Some suggestions were: mechanical weeding was easier in narrow beds, fuel use lower for shaping in wide beds, irrigation water use the same in wide beds and narrow beds where the latter is irrigated with alternate rows. Concentration of residue in windrows of wide beds easier. Also suggested soil texture important since it affects infiltration of water.

Weed control is a major issue with CA and although minimal tillage, soil cover and rotation can reduce weeds, it may take time to become apparent. This study looked at weed biomass, density and diversity with and without herbicide in a 19 year long term trial in the highlands of Mexico to evaluate the impact of the three pillars of CA on weeds. Generally weed density and biomass were lower in CA compared to CT. The three components of CA significantly reduced weed biomass that were lower when all three components were used. When herbicides were applied, weed biomass in CA was 91% lower in maize and 81% lower i wheat compared to CT. They conclude that if weeds are controlled in initial years, weed populations in CA systems are lower than CT systems.

Excessive tillage of soils in semi-arid Mexico has resulted in severe soil degradation, physical and chemical. The aim of this research was to evaluate how CA can reverse this issue over the long term (25 years) in a maize-triticale rotation under irrigation comparing conventional tillage against CA. They measured various soil physical properties and grain and forage yields. In 18 of the 19 soil quality indicators were higher for CA compared to CT. The highest estimated sustainability was 85% for CA, compared to 59% for CT. CA had greater structural stability with higher porosity values and lower bulk density, important factors for soil structure and crop yields.

This paper from Mexico looked at the the impact of conservation tillage (CT) versus intensive tillage (IT) on bacterial communities from experimental platforms that had practiced these three different tillage options for 25 years. The three tillage options were IT, CT and reduced tillage (RT) with residue with and without for each tillage practice. CT or conservation tillage showed higher species diversity and beta diversity while IT showed higher richness. IT results were grouped in the same phylum range whereas CT had a different range. CT also improved the soil physicochemical properties. Although not mentioned in the abstract, zero tillage and reduced tillage systems  led to the development of copiotrophic ecological niches, predominantly attributed to heightened organic matter levels stemming from the decomposition of agricultural residues and wastewater irrigation.

This study using maize and barley looked at the effect of various seed treatments (pesticides) had on roots and soil microbiota under CA. Seed treatments consisted of various commercial pesticide mixtures compared to a non-treated check. Soil and root samples were taken 2-3 times during the season and measurements taken on root biomass, root mycorrhizal fungi and pathogens, soil microbes and nematodes. They conclude that the pesticides and seed treatments had limited effects on root and soil microbiota.

Soil erosion is a major problem on tropical hillsides. This descriptive study in Mexico looked at water runoff and its runoff coefficients in four modalities of the “milpa intercropped with fruit trees” (MIAF) system, traditional and zero tillage, under rainfed conditions.  The MIAF.system reduced surface runoff by 46.13 % with respect to that obtained in LM-QR (minimum tillage with residue burning). The LO system (Zero tillage with crop residue distribution over the surface) had the lowest volume and runoff coefficient.

This paper looks at the effect of agricultural practices in the maize rhizosphere on soil bacterial communities in Mexico. Maize and bulk rhizosphere soil from conventional (CP) and CA practices were sampled at three growth stages and used 16S rRNAto assess bacterial diversity and community structure. Results showed that CA positively affected soil bacteria compared to CP. The bacterial community in the maize bulk soil resembled each other more than in the rhizosphere of CA and CP. Although agricultural practices did not alter the effect of the rhizosphere on the soil bacterial communities in the flowering and grain filling stage, they did in the vegetative stage.

This article looks at permanent bed planting (PBP) to improve soil quality, soil moisture conservation and stabilize yields of wheat in furrow irrigated systems in Mexico. It also looks at pre-irrigation (wet) and post-irrigation (dry) strategies in Durum wheat comparing conventional tillage and PBP (NT). They used 4 tillage-sowing irrigation and 5 nitrogen treatments over 3 years. The lowest germination was found in PBP-dry and the lowest yield. N fertilization management affected wheat quality, but not wheat yield, possibly due to high levels of soil mineral N available at sowing that were not measured in this study. They suggest research should address reduced plant stands with dry sowing in conservation agriculture to find management options that improve wheat emergence.

This paper used an integrated framework that included bioeconomic simulation, risk analysis, adoption theory and impact assessment to look at CA components and growing a new crop or variety performed over a 10-year period on farms in Central Mexico. They found significant differences in profit, net value, downside risk, and risk-aversion cost between double-component scenarios (and improved CA to a lesser extent) and all other scenarios, which suggested that disaggregating CA into smaller component packages could increase farmer adoption in risky contexts. The study highlighted the need for employing a range of research tools to understand the relative value of agricultural innovations and to identify and reduce trade-offs and uncertainty in farming systems. 

This study looks at looks at adoption of mechanization of appropriate equipment for resource poor farmers cultivating small and scattered plots using service providers. This paper uses the Scaling Scan tool to assess three project case studies designed to scale different Mechanization Service Provider Models (MSPMs) in Mexico, Zimbabwe, and Bangladesh. It provides a useful framework to assess the gap between international lessons learned on scaling captured in forty tactical questions over ten “scaling ingredients” as perceived by stakeholders involved in the projects, as well as private sector actors and government employees. Their results have important implications for similar development interventions aimed at increasing smallholder access to mechanization services at scale.

Interesting paper on the effect of CA practices and especially tillage (with and without), residue management (burned, incorporated or surface mulch) and fertilizer (with or without) on tilled or permanent beds (PB) on the soil microbial community in a long term maize-wheat experiment in NW Mexico. The soil organic carbon was highest in the PB, residue retained treatment and loweest in the burned and tilled plots. Bacterial communities were affected by tillage-residue, fertilizer and soil organic carbon. The paper has data on how the different bacterial communities were affected.