Conservation Agriculture Research Updates - May 2025

This article looks at the issue of declining soil health, soil organic carbon (SOC) and soil degradation and ways to sustain ecosystem services and human well being and food security in Africa. Aklso the need to do this when there are negative consequences of climate change. The paper says "soils of most agro-ecosystems in Africa have been subjected to land misuse and soil mismanagement, and thus are, severely depleted of their SOM content because of extractive farming practices. Thus, agronomic productivity, use-efficiency of inputs (e.g., fertilizers, irrigation, energy-based farm operations, seeds of improved varieties or choice of other species of animals or plants) and the nutritional quality of food produced is low." The paper then discusses options for reversing this declining soil health including CA, cover crops, crop-livestock systems, integrated soil fertility management, integration of crops and trees and more. The paper also suggests ways of encouraging farmers to adopt improved farming practices.

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.

This article from Mexico evaluates rainfed, monocrop maize CA cropping systems in semi-arid areas from 2 field experiments on 17 farmer fields planted from 2013-2020. The measured yield and profitability. Maize under conventional tillage was compared to maize on permanent beds with soil mulch, either monocropped or in rotation with triticale, oats, or common beans. Results varied between the two experimental sites. In one site bed planted maize was higher than conventional (CT), while in the other field yields did not significantly differ. In the 17 farmer fields bed planting yielded 70% higher maize than under CT. They conclude that "The most profitable system was permanent beds with a maize-bean rotation in field experiments and with maize monocropping in farmers’ fields."

This long term field experiment at 3 sites in India and one in Bangladesh to assess 4 scenarios: S1 - double cereal rotation with conventional practices; S2 - double cereal plus legume rotation with partial CA; S3 - double cereal plus legume rotation with full CA; and S4 - futuristic diversified cereal-legume rotations with full CA. The main objective was to study the dynamics and stabilization of SOC within these scenarios. Average results showed with passive C pools, , TOC, and Walkley-Black C followed S4>S3>S2>S1 in the 3 Indian sites but reversed S4 and S3 in Bangladesh. Stabilization of C as SOC was higher in the 3 CA scenarios compared to S1 and in rice-rice, compared to Rice-wheat. They concluded that "full CA systems with best management practices (S3) and best management practices with crop diversification (S4) are recommended for sustainable crop production in the major double cereal growing regions of South Asia.

This paper from India evaluated a 12-year old CA based pigeon pea-wheat cropping pattern on permanent broad beds with residue (CA-PBB), permanent flat bed with residue (CA-PNB) and conventional (CT). The results showed that the 2 CA treatments enhanced total SOC compared to CT. The CA flat bed showing the highest SOC at 0-5cm and 5-15cm depths. They conclude that residue input increases cumulative mineralization and SOC decay rate vis-à-vis helps to sequester carbon in the recalcitrant fraction, leading to higher stable carbon in soil.

The authors of this paper are looking at traditional grains like sorghum, pearl and finger millet to combat climate change and drought in sub-Saharan Africa (SSA) as alternatives to maize the staple food in this area. The main objective of this review paper is to identify suitable equipment for smallholders to mechanize growing these traditional grains. They reviewed six databases to find suitable equipment used globally. They found that the mechanisation of traditional grain production operations is lagging behind that of other cereals and so there is a need to work on development of suitable equipment  for smallholder farmers. They suggest use of two-wheel tractors and service providers as a way to move forward. Policy decisions and recommendations for improvement were made.

This paper from Iran looks at the effect of 5 years of CA managment on the quality and diversity of soil macrofauna in rainfed in semi-arid areas of Iran. Treatments included conventional moldboard tillage (CT), reduced tillage with a Delta  model and roller (RT1), Chisel plow and roller (RT2) and no-tillage. There were 3 subplots with no residue, 1/3 residue and 2/3 residue. Wheat rotated with chickpea was the cropping pattern. The results showed that no-tillage led to a significant increase in macrofauna biodiversity in both wheat and chickpea soils. Also keeping 1/3 residue led to an increase in macrofauna diversity.

This paper addresses the issue of managing the large amount of biomass straw after combining rice in India. The easiest and most common farmer way is to burn the straw so land preparation is easier, but this comes with negative environmental problems especially air pollution from the smoke. CA can be a good option since the surface straw can help improve soil health, but low temperatures and nitrogen levels slows decomposition rates, immobilizes nitrogen and hinders land preparation, although CA uses no-tillage. This paper applies fungal inoculants to enhance bacterial degraders. The paper also looks at the genomic insights for choosing appropriate decomposers. The paper talks about incorporation of straw, whereas in CA, the idea is to maintain the straw as a surface mulch and minimize soil disturbance through tillage. Just enough to sow the seed into the mulch with equipment designed to plant efficiently into the residue.

This experiment from dryland cotton areas of India looked at the impacts of tillage and weed management on soil quality index and system yield in a cotton-maize system. Treatments included various combinations of conventional tillage (CT) and no-till (NT) in cotton and maize with and without the legume Sesbania rostrata.Weed treatments (sub-plots) included use herbicide (H), herbicide rotation (HR), integrated weed management (IWM), and one hand weeding (HW). The experiment was run for 3 years. They measured 40 soil variables for soil chemical and physical properties. The soil quality index and yield increased by 23% and 52%, respectively for the NT with cotton + Sesbania rostrata residues–NT with maize + cotton residues–NT with Sesbania rostrata + maize stubbles compared to the farmer practice that used CT and no Sesbania. They conclude that NT for Cotton, Maize and Sesbania with residue retention and IWM had better soil quality and yield.

Despite CA being promoted and a possible solution for food insecurity resulting from climate shocks and soil degradation, adoption in Malawi is still low. This paper looked at social capital as a way of approving adoption. The interviewed 1512 smallholder farmers to find out how different social capital elements influenced farmer decisions to adopt CA. Factors that positively affected adoption were group membership, relations with leadership, land size, extension services, livestock ownership, and available credit. Full adoption of CA was limited compared to partial adoption. They conclude that better policy is needed to promote farmer organizations, community engagement, and training programs to enhance adoption.

This study is undertaken at the Ifugao Rice Terraces in the Philippines, an Agricultural Heritage system. They surveyed farmers in this region on the socio-demographic, environmental, and economic factors influencing the adoption and persistence of Environmental Conservation Agriculture (ECA). They found the shift to high-yielding rice in ECA led to a decline in the use of Tinawon rice, an important component of this Heritage site. They suggest it is important to balance modern practices with continued use of the traditional system to preserve biodiversity, soil health, and cultural identity. Climate change presents both challenges and opportunities for adaptation, making it essential to integrate traditional knowledge with modern techniques to build resilience. 

This paper from India looks at the causes of a plateau in rice-wheat yields in South Asia. They used a 2-year on-farm study to look at wheat productivity in a RW system. They introduced various system optimization practices (SOP) that include legume inclusion, NT wheat, Direct seeded rice, and bed planting. Benefits of SOP's were reduced global warming potential, reduces water use, reduced weed density, higher partial factor productivity, wheat yield and net return increases, lower energy use compared to traditional practices. They conclude that wheat production with SOP's of legume inclusion and zero tillage achieve higher productivity and profitability with less environmental footprint in the Indo-Gangetic Plains and similar agroecological regions.

This paper from India looked at the effect of CA and N management on soil N, P, and S release and the enzymes involved. The results showed that CA significantly enhanced the mineral N, Olsen P and CaCl2-S release and the soil enzymes involved compared to CT + R plots. They conclude that CA alongside optimum nitrogen management enhances the soil enzymatic activities and nutrient mineralization that results in higher crop output while maintaining soil health.

This article is concerned with the impact of climate change (CC) will have on the productivity of the rice-wheat system in the Indo-Gangetic Plains of South Asia and India that is the breadbasket of these countries. This long term research looks at the potential of long term conservation agriculture (CA) management to address this CC issue. The paper describes 6 different production scenarios with one the traditional system and 5 others that have various improvements on the traditional system including just NT wheat, both NT rice and wheat, addition of a mung bean legume, NT maize and wheat, and one with sub-surface drip for irrigation (SSDI). They conclude that overall, soil organic carbon was higher in all CA scenarios compared to the traditional scenario. "By substantially enhancing soil health and crop productivity, as well as boosting resilience, CA emerges as a promising solution for meeting the increasing food demand in Northwest India and beyond and cropping seasons between and across regions."

This paper from Malawi looks at ways to overcome the problem of climate change impacts that have affected food production. They looked at improved varieties on total productivity and nutrition under maize-legume CA systems over 13 years of on-farm experiments in Malawi. the 3 main treatments were 1. CT of sole maize planted on raised beds; 2. NT of sole maize on retained ridges + residue; and 3. CA maize intercropped with either cowpea, pigeon pea or groundnut on retained beds using NT. The results showed that total system nutrition was highest on the 3rd main treatment. The yields of maize were significantly higher in the 2nd and 3rd treatments irrespective of the variety grown. They conclude that "Conservation agriculture and NT systems have more influence on productivity of smallholder farms, despite the genotypes used (hybrids or OPVs)."

This paper from South Africa looks at the production performance, soil greenhouse gas emissions, and soil carbon sequestration of different crop rotations. They measured nitrous oxide and methane fluxes over one year and analyzed 20 years of historical data on soil carbon sequestration, yields, fertilizer use, and wheat protein content. Results showed that rotations that contained legumes and livestock produced more wheat and canola yields and higher wheat protein. All systems showed an increase in SOC over the 20 year period. They concluded that "Legumes and livestock incorporation in crop rotations interact with nitrogen management. Most N2O emissions occurred after precipitation in the otherwise dry summer, making reduction difficult as minimal management activities occur over this fallow period.

This paper used a meta-analysis of CA and/or biochar use on soil-nitrate-N, N20 emissions, biological N-fixation, N derived from the atmosphere, grain Y, and Nitrogen use efficiency (NUE). They used 87 papers from 15 countries in SSA with 1643 paired observations. Their results showed that on average over all studies CA and/or biochar significantly increased grain yield and NUE compared to conventional systems. In addition, Residue retention resulted in a significant increase in soil NO3-N and N2O emission, compared to conventional practices. Biochar also increased biological N-fixation, grain yield and NUE. N2O emission increased significantly in soils with < 0.05 % total N, while biological N2-fixation increased significantly in soils with > 0.2 % Total N.

CA is being used in this coastal area of the USA to improve soil health, reduce environmental impacts, and improve farmer profits. They commonly use cover crops, strip, minimal, and no tillage. The paper evaluates the changes in soil properties from various CA  practices. They evaluated 4 tillage systems: conventional, strip, minimal, and no-tillage; 3 winter cover crop systems; fallow, winter cash crop, and high biomass CC. They then measured 6 soil properties over 7 years. Altogether, soil carbon showed a more consistent response to conservation management than the other soil properties, which tended to show greater variability based on the time since tillage. They conclude that conservation practices need to be applied for multiple years in order to improve soil properties. 

This paper from Germany looks at crop rotation and cover crops on SOC and N content on yields. This 10 year dataset  from 6 locations in Germany was used to calibrate the DSSAT model. They then used a 4-year crop rotation with and without legume cover crops at the research sites with a no CC as a check. Results showed that business as usual (BAU) and no CC treatments had lower (SON) and SOC than with CC's included in the rotation. Legume CC's also did better than non-legume CC's although the latter had less N leaching. winter wheat and oilseed rape crops yields were better with cover crop rotations. Crop rotation with CCs significantly increased water productivity of cereal crops, but did not produce higher yield of winter and spring barley or silage maize compared with BAU unless only legume CCs were used in certain areas that are vulnerable to N losses. 

This paper looks at the effects of CA versus conventional management (CM) on 17 soil properties, microbial during 8 years of climate warming in China. Results showed an increase in soil health with CA management in terms of increased SOC, and soil microbial biomass carbon and fungal diversity. This led to increased wheat yields over the 8 years but only in CA. They conclude that CA management increases soil health leading to higher yields despite the climate warming trend. CM did not show this improvement.

This 15 year long-term experiment from Haryana State in India using a rice-wheat system was designed to measure the impact of 15 years of tillage and residue management on the soil quality index (SQI) and yields. There were treatments: 1. CT without residue (-R); CT with +R incorporated; Reduced tillage (RT) with -R; RT +R incorporated; NT -R; and NT +R left on surface. Soil measurements included various physical, chemical, and biological properties. Results showed that NT+R had the lowest bulk density and soil penetration resistance at the surface soil leading to better water infiltration. Also improved SOC, and microbial activities. Wheat yields were higher for NT + R, but lower for rice yields. This was related to using direct seeded rice and probably having more weeds than in the transplanted conventional rice. 

This study looks at the impacts of no-till individually and with other CA practices on nitrous oxide (N20) emissions and yields using a review of 1270 observations from 86 peer-reviewed articles. Results sho that yields increased by 9.1% while reducing N20 emissions by 6.8% compared to conventional tillage (CT). The results also showed that reduction of N20 emissions and yields were even greater when using other CA practices like residue retention and rotations; reductions in N20 of 15% and increase in yields of more than 30%. The mitigation of N20 emissions was higher in dry versus humid climates. They conclude that "Smallholder farms in Central Asia, South Asia, and sub-Saharan Africa appear particularly suitable for the adoption of conservation agriculture, whereas, in humid climates, high nitrogen (N) input management and silt-clay loam soil should be applied with caution. 

This paper suggests using DNA analysis to identify earthworm biodiversity. Earthworms are an important component of healthy, soil biodiversity. Traditional ways of identifying quantity and diversity is labor intensive and can only identify adult worms. This study used DNA (eDNA) metabarcoding using two different primer sets and next-generation sequencing, with earthworm hand-sorting from standard soil-pits in field planted for 3 years with grass-clover. The eDNA method found the same 8 earthworm species but was able to worm richness. The recommend using the eDNA method for better earthworm biodiversity monitoring.

This paper looks at the effect of cropping systems on larger macrofauna. They sampled 21 fields in France that were used for conventional, conservation or organic systems, either long-established (≥ 7 years) or in transition (≤ 3 years). Tillage, pesticide treatment and organic matter input intensity were assessed in each field. Macrofauna density and diversity, earthworm ecological categories, species richness and functional traits were investigated. They report that density and diversity showed few differences in respect to cropping systems with high variation across years and groups. They conclude that more information is needed on actual cropping systems in order to better assess the impacts of cropping systems on biodiversity.

This article from Ghana looks at the effect of CA adoption by smallholder maize farmers of their food security. 400 farmers were selected that had been introduced to CA. The findings of the study show that crop rotation, row planting, fertilizer application, improved seeds and cover cropping were the CA practices often implemented by the farmers. The main issue highlighted by these farmers was poor access to credit for applying CA but CA did improve their food security.