Conservation Agriculture Research Updates - March 2026

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 looks at the effect of cowpea cover crops and residue retention on yield of cash crops in Australian dryland cropping systems using the APSIM model. They assessed the combined influences of cowpea cover crops and three residue retention levels on soil water balance, soil organic carbon (SOC), nitrogen (N) dynamics, crop yield and gross margin across six crop rotation systems during the historical period (1985–2020), near future (2021–2056), and far future (2057–2092) in southeast Australia. They conclude that where residues are removed, the long-term adoption of cowpea cover crops could be a potential practice to sustain crop productivity with environmental co-benefits under climate change in the wetter parts of the dryland cropping region of southeast Australia.

The goal of this paper was to look at the long-term interactive effects of cover crops and residue retention on yield of cash crops and environmental outcomes in dryland cropping systems under climate change. They used the APSIM model to assess the combined influences of cowpea cover crops and three residue retention levels on soil water balance, soil organic carbon (SOC), nitrogen (N) dynamics, crop yield and gross margin across six crop rotation systems during the near future and far future in southeast Australia. Results showed cover crops decreased soil moisture on the day of sowing the succeeding cash crop but led to greater SOC stock,  reduced N loss through leaching, and enhanced N uptake and yield of cereals, but decreased N uptake and yield of field pea. The effects of cover crops on yield and gross margin became more positive in the far future. Cover crops were profitable in the wetter parts of the study region (east), but reduced gross margin in the drier west due to depletion of soil water reserves for the next cash crop.

This interesting paper looks at the problem of loose straw after combine harvesting wheat and other crops. One farmer solution is to burn this straw, but that has negative impacts and pollutes air. This paper reports the effect of residue distribution on soil properties and crop establishment and yield under no-tillage and controlled traffic in cereal (wheat-wheat-barley) and diverse (wheat-legume-canola) rotations, over the final six years of a larger 12-year rotation experiment in Australia. For each crop and rotation, residue was either spread evenly or burnt. Increasing residue amount had a positive effect on establishment and yield when conditions were dry around seeding and early crop growth stages, possibly associated with increased water availability with increased residue load. In the longer term, higher residue amounts resulted in increased soil nutrients behind the harvester, which increased yields in some years. Therefore, research to improve uniformity of residue spread behind harvesters is crucial. 

NT and stubble retention is common in Australia to protect soils from erosion. This 10-year (2008–2017) field experiment with 4 combinations of tillage (no-till vs cultivation) and stubble management (retention or burning) were applied annually from 2008 to 2011. In 2012, all plots were returned to no-till and stubble retention to determine the recovery of crop performance and soil properties from stubble burning and/or cultivation. Changes to ground cover, soil water repellency, soil water content, soil carbon and crop performance during a 6-year period (2012–2017) were compared with plots where no-tillage and stubble retention had been practiced for several decades. Average grain yields where stubble had always been retained were significantly (P < 0.001) greater by 22–33% than where stubbles had previously been burned.

This paper looks at the impact of CA and changes in crop rotation in the last 15 years that led to less disturbance of mouse burrows and increased ground cover and food supply on rodent pests. This study was justified since irregular outbreaks of mice in grain cropping regions in Australia and the damage they cause, makes it important to understand when and where mouse populations increase so that management strategies can be improved. They utilised a 20-year long-term mouse population data set collected prior to the introduction of CA farming practices and a more recent 8-year data set after CA to compare changes in mouse population abundance in a typical dryland grain cropping system in Australia. Mice are now resident year-round within crops and stubble and appear to only spill over into margin habitats. Previously developed recommendations for mouse management that include their control while in margin habitats may no longer be valid.

This study compares CT with NT with stubble burning and stubble retention and N fertilization on soil carbon and fractions and N. After 50 years, the tillage regime, addition of N and stubble management were all important in influencing carbon pools in the 0.1m depth with N and the tillage regime the most important. But stubble management was important with retention increasing total nitrogen content, stabilizing the C fraction, and increasing the microbial biomass. They conclude the importance of stubble retention and N fertilization in conservation agriculture clearly shows improvement in soil health and maintenance of soil C levels.

The link above will take you to a copy of this interesting book on CA farming in  a part of Australia.It covers the history of conservation farming from the early 1960's to the early 2020's. It covers the adoption of CA and mentions some of the leading innovators - NSW State agricultural scientists, University and CSIRO scientists, consultants in the private sector, agribusiness, pesticide companies, farm machinery and engineering sector plus progressive farmers. Bare fields of tilled soil are now rarely seen.Instead the fields are covered with crop and pasture residues that protect the soil and water. There have been adoption of many varied rotations. This book salutes all those who have been part of this soil revolution.

This article looks at regenerative agriculture, one of several sustainable narratives that have emerged as solutions for challenges facing agri-food systems. The paper uses 4 prominent narratives -- organic, CA, Sustainable intensification and agro-ecology -- and then discusses how RA fits in with these 4 narratives and what potential it has. They show that there are a number of differences and similarities that have coalesced to drive the emergence of RA. They suggest that regenerative agriculture risks inhibiting deeper agri-food system transformations that address both social and ecological challenges and is not the unifying sustainable agriculture narrative it claims to be. 

This paper from Australia looks at stubble born cereal diseases related to adoption of CA. The fungal pathogens that cause these diseases can saprotrophically colonise retained cereal residues, which may further increase inoculum levels post-harvest. The study looked at 3 stubble borne fungal pathogen sand compared under a range of moisture regimes of six cereals varieties - 2 wheat and barley and 1 durum and oat. Saprotrophic colonisation also increased with increasing relative humidity for all pathogens and varied by cereal type. They concluded that reduced cereal harvest height, may limit saprotrophic colonisation and improve stubble-borne disease management in conservation agriculture systems.

This paper looks at the impact of a "One-time tillage (ST)" after three years on soil microbiomes and functions in a long term no-till farming system under crop stubble and fertilizer management practices. The results showed that ST had marginal effects on microbial richness and diversity, enzyme activities, and catabolic function, but significantly affected the abundance of some microbial taxa that are relevant to carbon degradation. Stubble retention, regardless of tillage and fertilizer management, mainly increased the abundance of copiotrophs. Among the management practices, stubble retention was the main factor that contributed to increased richness and diversity of the soil bacterial and fungal community. Fertilizer application, regardless of tillage and stubble management had minimal impact on bacterial and fungal richness and diversity, enzyme activity and catabolic function. 

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 reports on the residue dynamics in a 12-year experiment (2007–2018) in the Wheatbelt of Western Australia, comparing rotations that included: cereal (cereal/cereal/cereal); diverse (wheat/legume/canola); farmer (wheat/barley/break – legume or fallow); and wheat monoculture. Crop residue was either spread behind the harvester (retain) or windrowed at harvest and burnt before seeding (windrow burn). Within rotations, residue quantity was highest with retained residue in the cereal rotation and wheat monoculture, averaging 5.0 t ha−1 prior to seeding, which could present management problems at seeding time in some years. Residue quantity was reduced to optimal levels by including legume crops or canola in the rotation, as these residues were more rapidly broken down than cereal residues, whilst maintaining residue retention practices.