Conservation Agriculture Research Updates - April 2026

This study looks at the impact of various soil management practices on soil microbial diversity in a no-till dryland soybean system in the USA. Treatments included cover crops and nutrient management including the use of poultry manure. Targeted amplicon sequencing of 16S rRNA and ITS2 genes was used to study the bacterial and fungal community composition. Poultry litter amendment and cover crops significantly influenced soil bacterial diversity. Fertilizer sources had different bacterial populations while cover crops influenced the fungal communities. Differential enrichment of advantageous bacterial (Proteobacteria, Actinobacteria and Acidobacteria) and fungal (Mortierellomycota) phyla was observed across the treatments. They propose a long-term study to provide more inferences on soil microbial community response to management changes.

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 study collected data from a long-term experiment in a semi-arid region of Tunisia. Their results showed that no-till (NT) increased soil organic carbon, soil microbial biomass carbon (SMBC), arbuscular mycorrhizal fungal root (AMF) colonization and soil microbial respiration in the 0-20 cm topsoil compared to CT. In addition the rotations Faba bean-Durum wheat-Barley and Faba bean-Durum wheat increased SMBC, AMF and respiration. They conclude that the current results highlight the benefit of adoption of minimum or (NT) combined with crop diversification on soil health.

In South Africa, arable land for crop production and permanent pastures accounts for 10–12% of the total land surface. South Africa is classified as semi-arid, with the average rainfall below the global average.This paper describes the role CA can play in more water use efficient agriculture that is not only for grain crops  but also other agricultural commodities. This review highlights the results of research to date and the challenges for practicing rainfed conservation agriculture in South Africa.

This is a preview of the third volume of this book series on the topic of advances in Conservation Agriculture that looks at the effectiveness of CA in differing countries and contexts. The following are 6 major sections. 1.Global adoption and spread of Conservation Agriculture; 2.Conservation Agriculture in west and central Canada;
3.Conservation Agriculture in the USA; 4.Conservation Agriculture in Central America, the Caribbean and Mexico; 5.Conservation Agriculture in South America; 6.Conservation Agriculture in Europe; This book provides an authoritative review from an array of international experts on the adoption of CA principles in different regions around the world. The final volume in this collection reviews the effectiveness of CA in differing contexts (e.g. in drier conditions where water conservation is important or in areas with poor soil) and refers to the wealth of research and experiential evidence currently available.

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.

This study uses an endogenous switching regression model to a nationally representative sample of 1901 wheat fields in Morocco to analyze the impacts of partial or full adoption of all three components of the CA system. Model results show that adoption of the complete CA system leads to 307 kg/ha (35 %) higher yields, US$99/ha (44 %) higher gross margins, and 23 kg/capita/year (38 %) more consumption of wheat relative to the conventional system. Adopting only two of the 3 pillars also leads to improved livelihood indicators compared to adoption of only one or none of the pillars. But adoption of one pillar is better than none. They conclude transition from the conventional system to CA requires the following: (1) flexibility to let farmers incrementally adopt one or more of the CA components, learn at their own pace, use some of the benefits, and improve it over time to exploit the full potential of the CA system with close follow-up and technical support from experts and extension specialists; and (2) sustained policy and institutional supports that provide incentives for farmers to adopt and for the private sector to be actively involved, especially in service provision.

This paper was given at the 1st International conference on Sustainable Land Management in Indonesia. This paper looks at the impact of CA in a semi-arid area of Indonesia. All the farmers in this project say that CA increased maize productivity and some farmers were even able to plant two maize crops with good yield in a drought year. Integrating forage into CA based farming also enabled farmers to provide enough feed 1-2 cattle per household. In this area basins were dug and then CA used. Labor was an issue but I suggest they make these basins permanent to lessen labor in the second crop/year. The residue mulch is also needed for animal feed. Similar to other dryland areas.

Conservation agriculture (CA) has been promoted to mitigate climate change, reduce soil erosion, and provide a variety of ecosystem services. Yet, its impacts on crop yields remains controversial.This paper looks at the probability of yield gain when switching from CT to CA worldwide. Relative yield changes were estimated with machine learning algorithms trained by 4403 paired yield observations on 8 crop species extracted from 413 publications. CA has better productive performance than a no-till system (NT), and it stands a more than 50% chance to outperform CT in dryer regions of the world, especially with proper agricultural management practices. Residue retention has the largest positive impact on CA productivity comparing to other management practices. The paper concludes CA appears as a sustainable agricultural practice if targeted at specific climatic regions and crop species.

This is chapter 6 in a 2019 book entitled "Smallholder Farmers and Farming Practices: Challenges and Prospects" available at https://novapublishers.com/shop/smallholder-farmers-and-farming-practices-challenges-and-prospects/  This chapter looks at the challenges of farming in a semi-arid area of Africa with erratic rainfall and frequents risks of crop failure. The chapter concludes that smallholders could optimally improve crop yield if they adopt appropriate technologies. They show improved crop yields with CA that also has environmental and socio-economic benefits for achieving sustainable dryland agriculture under the changing climate in Botswana.

The objective of this study was to investigate the effects of tillage, crop rotation, and residue management on soil CO2 fluxes, carbon stock, soil temperature, and moisture in the semi-arid conditions in the Eastern Cape of South Africa.They compared CT vs NT for different maize systems with and without residue removal and addition biochar. The results of the study show that NT can potentially reduce CO2 fluxes. In the short term, amending soils with biochar did not reduce the CO2 fluxes compared to R+, however the soil moisture increases were comparable.

This paper contends that efficient water use is vital for arid zones that rely on irrigation from available water. This paper's objective was to look at the effect irrigation before or after sowing with conventional or conservation agriculture practices on beds on bacterial community structure in soils. The bacterial communities were identified with Illumina MiSeq sequencing where the 16S rRNA gene was targeted. They conclude that soil water content was the principal factor shaping the bacterial community structure. While the three most dominant phyla were affected by the difference in water content in the tillage practices under dry and wet sowing, it was at the genera level that these fluctuations were more obvious.

This chapter 17 in the book "Food Security for African Smallholder Farmers" was selected to highlight the importance of CA adoption to help mitigate climate change in Southern Africa. Crop yields in the smallholder sector have continued to decline, and farmers whose livelihoods rely on agriculture are poor and food-insecure. This chapter provides a review on how the farmers can build resilience to climate change through adoption of conservation agriculture (CA). Conservation agriculture has several positive attributes, which enable crop productivity in semi-arid regions of southern Africa. Among other advantages, CA maintains or improves soil structure; reduces soil exposure to water and wind erosion; increases water infiltration and reduces loss through evaporation. Minimum soil disturbance slows organic matter breakdown and mineralization resulting in organic carbon build-up. 

This is a Pearl Millet (PM) based paper for low-irrigation, semi-arid areas of North Indian Plains. The study looked at ZT with and without residue, ZT and ZTR compared with CT using 3 PM cropping patterns that included, chickpea, mungbean and PM fodder over 2 years. Comparisons were made for yield, mineral biofortification and GHG emissions. Results showed a significant increase in pearl millet yield attributes, grain and stover productivity, nutrient uptake, and micronutrient biofortification in the PM–CP–MB cropping system under ZTR relative to other treatment combinations. On-farm trials confirmed the same result.

This study in semi-arid climates in Spain looked at nitrous oxide (NO) emissions and related microbial communities and their interaction with enhanced efficiency N-fertilizers in the transition year from tillage to no-tillage. They looked at the effectiveness of DMPSA (nitrification inhibitor) + NBPT (nitrogen stabilizer that slows the conversion of urea to crop available nitrogen) applied with urea and calcium ammonium nitrate to mitigate NO in rainfed barley. The highest N2O emissions were measured 49 days after harvest (immediately after a rainfall event that reactivated soil microorganisms), for the treatment with fertiliser without inhibitor combined with tillage. No tillage led to a higher abundance of Cyanobacteria, Verrucomicrobia and Bacteroidetes and resulted in better crop and higher plant density compared with tillage, thus increasing yields and N use efficiency and decreasing N2O emissions. They concluded that shifting from conventional tillage to no tillage enhanced the balance between N use efficiency and yield-scaled N2O emissions in the first year of conversion, particularity with the use of the double inhibitors.

This seven years study was done to study the effects of different tillage practices and residue levels on weed shift, diversity and crop yields. Results show that annual weed species were dominant in conventional tillage (CT) and reduced tillage (RT), whereas a shift towards perennials was observed in zero tillage (ZT). CT recorded lower weed densities after 7 years. A shift in dicot weed species with higher weed density and biomass and a small decrease in monocot weeds was observed in ZT. The anchored residues 10 and 30 cm, recorded lower monocots and total weed count over no residue. They conclude that integrated weed management (combination of herbicide and removal of chance weeds) are efficient strategies to minimise the weed infestation in CA and these methods not only reduce the over reliance on herbicides but also improve the productivity of pigeon pea (Cajanus cajan L.), castor (Ricinus communis).

This article applies an endogenous switching regression model to a case study of 2296 wheat fields in Morocco, to provide evidence on the socio-economic impacts of residue retention. 30% and 60% plus of crop residues were retained respectively on 35% and 14% of wheat fields. These levels of residue retention led to 22% and 29% more yields, 25% and 32% higher gross margins and 22% and 25% more consumption of wheat, respectively. Residue retention is economically and biophysically beneficial even for owners of livestock as the monetary value of the additional grain yield more than offsets the cost of purchasing an equivalent amount of feed from the market—all providing good economic justification for residue retention. Development and/or import of alternative feed sources, introducing crop insurance, and raising the awareness of the economic, biophysical and environmental benefits of residue retention among farmers are needed.

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 a paper that looks at selection of suitable wheat genotypes for CA that maintain productivity under drought conditions. The screened bread and durum varieties under CT and CA for three crop seasons under rainfed conditions in Iran. The wheat cultivars performed better in conventional than conservation agriculture system with grain yield superiority varied from 4 to 35%, depending on amount and distribution pattern of precipitation over crop seasons. They concluded there was a positive interaction of genotype and traits under the two tillage systems with some traits (i.e., number of spike/m−2, SPAD reading, normalized difference vegetative index (NDVI), days to heading, 1000-kernel weight and grain filling duration)  effective in genotype adaptation to a particular system. The wheat genotypes significantly interacted with different tillage systems, implying the need for specific adaptation to tillage systems and environments.

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 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.

This paper was included because of the debate about use of residues in crop-livestock systems in Africa and their impact on adoption of CA. The area in Zimbabwe for this study is a semi-arid area where yields are low and residue biomass is limited. The paper looks at the economic tradeoffs and profitability of using residues for feeding the livestock or livestock using household surveys. The results show that a maize-macuna rotation can reduce tradeoffs of residues for mulch or feed. The results also show that The poverty effects of all considered alternative biomass options are limited; they do not raise income sufficiently to lift farmers out of poverty. Further research is needed to establish the competitiveness of alternative biomass enhancing technologies and the socio-economic processes that can facilitate sustainable intensification of mixed crop-livestock systems, particularly in semi-arid environments.

This is a chapter in a 2019 book 'Innovations in Sustainable Agriculture" that looks at constraints to rainfed production globally. This chapter looks at some issues such as soil conservation, water and nutrient use efficiency and mitigation of climate change, suggesting some sustainable cropping and management strategies using examples from Mediterranean agroecosystems. The authors conclude that sustainable agricultural management in drylands should be primarily based on conservation agriculture practices and associated local-based crop residue management systems.