Conservation Agriculture Research Updates - March 2026

Manual methods of farming are common in Africa and also in Zimbabwe where this paper was written. It measures the fuel consumption needed to use a two-wheel tractor to relieve the drudgery of manual farming in this country. This is important for calculating the cost of mechanizing agriculture and GHG emissions. This study measured fuel consumption for 2-wheel tractors in direct seeding for sorghum and pearl millet crops in sandy soils at varying speeds of operation. The information in this paper can be used by farmers and other operators of 2WTs for planning the fuel quantity and budgetary requirements.

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.

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 study from Finland looked at the long-term (2000-2019) effects of primary tillage practices on environmental risks and nutrient input use efficiency. There were 3 tillage treatments moldboard plowing (MB) to 25cm, reduced stubble tillage (RT) to 15cm, and no-tillage (NT). P fertilizer was not used after 2008. Current results showed that MB and RT were comparable primary tillage methods but NT increased the N and P balances. However, barley yield was higher for MB and RT (12-13%) compared to NT. The research didn't mention if residues from the previous crop or cover crop were left on the soil surface, but did say all tillage treatments were planted on the same day. CA uses NT but is a better practice when residues are left as a surface mulch. Earlier planting with NT may also benefit the crop by having better soil moisture.

This paper looks at Climate Smart systems like CA and intensification in millet cropping systems. They looked at residue management and tillage practices in pearl millet (PM) yield stability and biofortification. NT systems with intercropping of other legumes with PM, increased yield of PM, micronutrient content, protein and oil content, and the fatty acid profile of PM compared CT-based tillage systems. The best combination for achieving stable yields and micronutrient fortification was residue retention in both (wet and dry) seasons coupled with a NT pearl millet + cowpea-mustard (both with and without barley intercropping) system. 

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 paper looked at productivity, profitability, and sustainability of barley genotypes that adapt to restricted resource settings and low energy-carbon management. 5 barley genotypes were evaluated under two contrasting  tillage/residue systems; NT + residue retention (NT+RR) and conventional tillage + residue incorporation (CT+ RI) in the semi-arid plains of NW India. The (ZT+RR) system, and the barley genotype RD-2552 followed by BH-946, provided significantly higher crop productivity and profitability compared to CT+ RI and other genotypes. The NT-RR system enhanced energy and carbon use efficiencies and provided lower energy-carbon footprints.

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 study from Spain, evaluates no-till, cover crops, and organic amendments as an alternative for conventional practices (CM) for rainfed cereal cropping on a calcareous soil based on the analysis of soil water retention curves (SWRC) and soil structure. The alternate treatment (AM) includes no-tillage (18 years continuous) after conventional tillage, crop rotation, use of cover crops and occasional application of organic amendments. CM involves continuous conventional tillage (chisel plow), mineral fertilization, no cover crops and a lower diversity of crops in the rotation. Their results showed more macropores under CM while mesopores and micropores were the same in both CM and AM. There were more stable macroaggregates in AM than in CM, as well as more organic C storage, greater microbial activity, and biomass. They also say that adoption of AM would not lead to a loss in yields.

Climate change is causing declining rainfall (more variability) and increasing temperature extremes and when added to declining soil fertility, food security in rainfed Morocco is threatened. The objective of this study was to systematically evaluate agronomic, economic, and soil fertility indicators under CA and conventional tillage (CT) using field experimentation (medium-term) and simulation modeling (long-term) for a clay soil in Morocco. They looked at the effect of CA on wheat, barley, lentil and chickpea to determine yield, stability, profits, WUE, and soil fertility. They also used Dynamic simulation modeling to assess the long-term effect of adopting CA and CT in these cereal rotations. Both their 5-year field experiment and the modeling showed that adoption of CA improves a range of agronomic, economic and soil fertility indicators compared to CT.

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.

With more dry spells in Southern Africa in recent years, the interest in CA to secure crop yields in rainfed areas has grown. This study in Zimbabwe looked at the effects of CA on finger millets growth, yield and water-use efficiency. There were 5 treatments 1) conventional tillage (CT), 2) CT + mulch (partial CA1), 3) reduced tillage only (partial CA2), 4) reduced tillage + mulching (partial CA3) and 5) reduced tillage + mulching + intercropping (full CA). All mulched treatments had 15-32% more soil water content over the two growing seasons compared to the control resulting in better finger millet yields. The full CA treatment achieved the best finger millet grain yield. They concluded that CA, particularly when practiced in full, was more effective at offsetting the water limitations imposed by intra-seasonal dry spells on finger millet and significantly improved productivity.

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 paper mentions that maize, wheat and rice account for 90% of the total cereal production globally. They suggest that a new approach to cereal production is needed to overcome food insecurity, climate changes and unsustainable land use. They propose that integrated crop management (ICM) is an avenue to explore. This article reviews 108 studies from literature over the last 23 years.The review the data from Asia, China, USA, and Africa. Their data shows that ICM increased yields in rice, wheat and maize but despite this potential, widespread adoption faces technical, climate-related and economic issues.  They suggest that overcoming these issues requires targeted training, improved extension, and supportive policies.

Low soil fertility, water holding capacity, and climate change threatens dryland farmers especially on sandy soils. This paper looks at sorghum with CA to address this problem but also looking at genotype, planting time, tillage and rotation on a sandy, dryland soil in South Africa. Tillage was CT and NT, planting early and late, and rotating wit cowpea or monoculture sorghum. Early planted sorghum yielded more than late planted. NT had higher SOC, available P and K than CT. They conclude that results show that positive effects of early planting and NT on sorghum grain and dry matter yields, while effects on soil properties were greater during the season with higher rainfall, with no effects of cultivar and rotation on this infertile sandy soil.

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.

This is another adoption paper from the Mediterranean region -- Morocco, Spain and Tunisia. The study objectives were to investigate the sociocultural aspects of CA adoption, where they examined farmers’ understandings of ‘good soil management’ and a ‘good farmer’ identity. Crop rotation was a prominent concept cognitively tied to fertilizer application, bridging conventional and reduced tillage practices. CA farmers’ mental models of soil management were also more complex than conventional farmers. The ability to have good productivity and experience and knowledge were the most prominent aspects of farmers’ understanding of a ‘good farmer’. For CA farmers, environmental responsibility and innovation were important, whereas for conventional farmers, tillage and the use of mineral fertilizers, was valued more highly.

This paper's objective was to identify suitable agricultural strategies with high yields, energy use efficiency (EUE) , and carbon use efficiency (CUE) for an array of different crops grown in India - cereals, legumes, oilseeds, and sugarcane in both rainfed and irrigated cropping systems. Irrigated systems had higher environmental impact (EI) and carbon footprint (CF) than rainfed systems. But rainfed crops had higher CUE than irrigated ones.  Adoption efficient irrigation strategies (micro irrigation), enhanced fertilizer use efficiency (site specific nutrient management or slow release fertilizer), conservation agriculture (conservation or reduced tillage) rice cultivation methods (SRI or Direct seeded rice) were some mitigation strategies identified.. 

This paper looks at ammonia (NH3) emissions under field conditions since they have impacts on health, climate change, and natural environments. They used fields with barley in Spain to compare NH3 losses in NT and CT plots. NT plots produced the highest NH3 emissions after applying basal and topdress N fertilizers with basal having more NH3 emissions than topdressed ones. They conclude that NT requires the optimized management of N (timing, rate and particularly source) to abate the potential side effects of NH3 volatilization, while the use of robust measurement methods are needed with enough replicates to increase the precision in estimating differences.

This paper looks at the issue of sulfur deficiency in Pearl Millet in dryland areas of India using a field experiment with CA and foliar applications of S (ammonium thiosulphate). Their results showed that pearl millet grain and protein yield were significantly higher under no-tillage +3 t/ha crop residue mulching (NTCRM) as compared to no-tillage without mulch (NoTill) and conventional tillage (ConvTill), whereas the stover yield under NTCRM and ConvTill remained the same. S application also resulted in higher grain protein, yield and net returns than no S in the control.

This paper investigates the effects on no-till (NT) and shallow conservation tillage (RT) in combination with cover crop mixtures in rotations with at least three different crops in on-farm experiments in Germany. Experiments were done in 18 farms and 2 experiment stations over 6 years. Yields of cereals, oilseed rape, maize, soybean and peas were slightly lower under no-tillage than under conservation tillage. Cover cropping did not affect crop yields. Tillage and cover cropping had no influence on weed control in the subsequent main crop. They conclude that CA with minimum tillage had slight advantages compared to the no-till system under their farming conditions.

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. 

This paper looks at the impact of agricultural intensification on arthropods, especially ground-dwelling predators that are negatively affected by tillage. They hypothesize that reducing soil disturbances conserves arthropod populations in the field and reduces the for chemical pest controls. They used pitfall traps in cereal fields with CT, Reduced tillage (RT) and NT under CA management. Overall, the activity-density of ground-dwelling predators was higher in fields with minimum soil disturbance and generally declined with increased distance to semi-natural habitats. Body size of beetles was also larger with less disturbance. The results obtained in the present study show that soil disturbances significantly influence arthropod abundance and diversity.

This study looks at the impact of CA on SOC dynamics in sweet sorghum systems in South Africa. They compared NT vs CT; two rotations, sweet-sorghum/winter grazing vetch/sweet sorghum and sweet-sorghum/winter fallow/sweet sorghum; three crop residue retention levels: 30%, 15% and 0%. Tillage was the main factor that influenced SOC with NT increasing SOC more than CT. Increased residue retention resulted in higher microbial biomass.

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.