Conservation Agriculture Research Updates - March 2026

This is an interesting article that looks at straw biochar's impact on soil fertility, GHG emissions, grain yield, carbon footprint (CF) and net ecosystem C budget (NECB) in an arid region in China based on a 2-year field experiment using 3 biochar quantities and comparing against no biochar. Their results showed that biochar significantly reduced soil GHG emissions, but the highest rate increased methane emissions. Biochar lowered the CF and enhanced the NECB, primarily through increased net primary production and improved soil fertility and crop yields. They conclude that "biochar improved crop yields, NECB, and soil carbon storage while reducing GWP, GHGI, and CF."

This paper from Rwanda looks at the low yields of maize, a critical staple crop in this country. The study evaluates the agronomic and economic results of CA compared to conventional systems (CT) by interviewing 222 farms in dry areas of Eastern Rwanda. They found that CA farmers incurred higher total production costs, particularly for fertilizers, seeds, weeding, and irrigation, while CT farmers had significantly higher land preparation costs. But CA achieved 40% higher net profit, 20% higher maize yields, and higher P use efficiency compared to CT. They identified irrigation frequency, seed rate, and nitrogen and phosphorus fertilizer application as key determinants of maize yield using CA compared to CT. 

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 paper looks at the impact of CA and fertilization on durum wheat in a dry region of the Mediterranean. They looked at two wheat genotypes and compared NT with CT and two fertilizer treatments. They then evaluated environmental, economic, technical ad quality traits. One wheat variety was better than the other. NT was better yielding than CT. Low emission fertilization did not reduce crop performance and its combination with NT showed a higher economic net return. They conclude. that these two treatments improved environmental, and economic sustainability but also the health qulaity of wheat under water limited situations.

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 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 s based on an on-farm field trial under a long=term no-till (NT) system to evaluate the residual effect of one-time occasional tillage (OT) on crop performance, soil water, and water-use efficiency (WUE) one and two years after OT implementation from a dryland area of Morocco. Shallow and Deep OT options were evaluated with and without residue retention. 3 crops all grown under NT were evaluated - Durum wheat, faba bean, and chickpea. Results showed that the grain yield of wheat and chickpea were negatively affected by OT for all years considered. Average soil water storage measured at 0–60 cm at sowing was also lower in deep OT (133 mm) compared to NT with crop residue retention (151 mm) for all years and rotations considered. The comparison of WUE between treatments showed that, under NT with crop residue retention, the crops produced more grain and aboveground biomass per mm of water. 

Soil sodicity is expanding in arid and semi-arid areas of the world. This paper examines the reclamation potential of CA based management on this soil issue. They look at NT, use of legumes in rotation, residue mulch (R+), and sub-surface drip irrigation (SDI)  for 3 years in a rice-wheat system in India. The paper provides detailed results on productivity, economics, water and N use efficiency, soil pH, exchangeable sodium percentage, extractable anions, soil organic carbon, soil solution cations. They conclude that CA practices can reduce sodicity and improve soil chemical properties for a profitable crop production.

This book chapter reviews the benefits of CA and its potential to conserve fragile soil and water resources in semi-arid environments. In CA tillage practices are coupled with crop rotations and cover cropping where reduced soil disturbance results in at least 30% of residue remaining on the soil surface. Crop rotation coupled reduced tillage also enhances soil properties. CA also reduces evaporative losses and conserves groundwater while enhancing soil stability and reducing wind erosion in semi-arid areas. They conclude that developing management strategies to efficiently use irrigation water and capture precipitation and soil water in rainfed environments is crucial to avoid degradation of soil and water resources. 

This paper from Uzbekistan looked at soil productivity and yield of a legume based rotation comparing CT with NT in a saline soil in an arid area. CA consistently out yielded CT for wheat, millet, chickpea and maize over two years. The increased residue retention under NT facilitated soil porosity, structural stability, and water retention, thereby improving soil quality and organic matter content. Soil salinity decreased under NT compared  to CT, reducing salinity buildup. They concluded that the NT method with legume-based intensive cropping helps maintain soil health and crop yield leading to more sustainable land management of drylands.

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.

This article assesses the adoption of CA by smallholder farmers in semi-arid areas of Tanzania. They surveyed smallholder farmers in 4 villages with a random sample of 260 households -- 134 CA adopters and 126 non-adopters. The results show that extension services led to a better quality of CA practices on CA farms. Gender, access to extension services, access to agricultural inputs, participation in farmer groups, and access to credit for agriculture significantly influenced the adoption of CA. Adopters achieved higher yields and higher farm income compared to non-adopters. They conclude that more resources are needed for better extension and mechanization to help scale up adoption of CA together with better monitoring and evaluation to measure impact and sustainability in semi-arid areas.

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 paper from Brazil looks at the role of cover crops to improve soil fertility, plant nutrition and soybean yield in the Cerrado area in a dryland area. There were 8 cover crops, and fallow preceding soybeans grown in the off-season. This area had cultivated soybeans under no-till for 10 years. They measured the biomass of the cover crops, but also soil chemical and biological properties, soybean foliar nutrients, yield and quality. Data can be found in the paper and abstract. They concluded that "Cover crops improved soil fertility while increasing soybean productivity, thus being an effective strategy for the achievement of sustainable soybean production."

This article explores the interaction of genotype (16 cold tolerant) and tillage (3) for chickpeas in dryland areas of Iran over three cropping seasons. Tillage treatments were moldboard with residue removed (CT); minimal tillage (MT) with a chisel plow with residue; and no-till (NT) with residue retained. Results were positive for no-till + residue with increases in SOC, potassium, phosphorus, nitrogen and soil moisture compared to the start of the experiment. There were differences in performance between the different genotypes with some better with no-till and others with MT and others with CT. Chickpea genotypes cultivated under the NT system demonstrated superior performance (41%) in comparison to those grown using conventional tillage (CT) practices during the third year.

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 paper looks at cassava using CA in Peru. The objective of this study was to compare soil properties, cassava physiology, and yield under conservation agriculture (CA) and traditional agriculture (TA) practices, with and without mulch, in a water-scarce environment. CA out performed TA for several measured properties and they conclude CA is superior to TA in this drought prone area and improves soil properties, cassava physiology and yield.

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.

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 meta-analysis compares the yield and nitrogen use efficiency (NUE) between conservation tillage (CA?) and conventional (CT) for different cropping systems , mulching methods, N levels and addition of manure in US and China. The results show that CA at high-N enhanced the yield and NUE, and reduced the yield and NUE at low-N, compared to CT. NT with leguminous cover crops (LCC) significantly increased wheat yield NUE under low-N compared to CT. They conclude that based on the results, moderate N with LCC and manure application is recommended for growing winter wheat in dryland regions of the USA and China.

This is a second 2022 article on cover crop benefits. It focuses more on replacement of summer fallow with cover crops in semi-arid regions and proposes this benefits soil health. It looked at the effects of long-term CC in no-till winter wheat - grain sorghum -fallow system. Fallow replacement treatments were spring-planted and included peas for grain as well as one-, three-, and six-species CC mixtures compared with summer-fallow. Half of each CC treatment was harvested for forage and the other half remained standing after termination. They conclude that simple CC mixtures and CCs managed for hay provide similar soil benefits as diverse CC mixtures or CCs left standing in this semi-arid environment.

This is Chapter 8 in a new 2024 CRC Press book on soil and drought edited by Rattan Lal. The author suggests CA is increasingly endorsed as a type of Climate Smart Agriculture, contributing to both climate change adaptation and mitigation. The objective of this chapter is to describe and review the benefits of CA increasing water use efficiency in dryland agriculture where water is the most limiting factor and the impacts of SOM on soil hydrological properties and crop yields. Management of soil carbon is also central to maintaining soil health and ensuring global food security. The organic carbon content of soil is a key indicator of soil health that indicates the efficient functioning of many ecosystem processes.

This paper looks at phosphorus (P) management needs in a CA wheat system in a semi-arid eco-region in India in a two year field trial. There were three tillage treatments; conventional tillage without residue (CT-R), NT-maize residue, and NT with maize reside (NT+R). And 5 P treatments. NT+R plus P had the highest yield but also the best amino acid and net protein yield compared to the other treatments. The NT + R plot that received 17.2 kg P ha(-1) + phosphorus solubilizing bacteria demonstrated higher P agronomic efficiency and recovery efficiency (similar to 53%) over the control. 

No-tillage (NTR) with residual plastic mulch is being adopted in arid regions of China to reduce plastic residue, soil disturbance, and improve water use efficiency (WUE). They compared conventional tillage (CTN) and NTN with new plastic mulch with those of 1,2 and 3 years of NTR on soil physical, soil water, maize root and shoot growth, yield, and economic benefits. They showed that the longer duration of NTN and NTR, the higher the bulk density and lower soil porosity compared to CTN in the 0-30 cm depth. Read the paper for more results. They conclude that NTR for 2 years can be recommended and help reduce the problem of plastic residue while increasing economic benefits.

This article looks at soil microbial communities that play a role in nutrient cycling, organic matter decomposition, SOC, and GHG emissions in particular under CA under a 10 year rainfed, semi-arid pigeonpea - castor bean cropping system. It looked at tillage and residue management in CA management on soil bacteria diversity, , enzyme activity, GHG emissions and nutrient availability. Overall, the results of the study indicate that CA improves the relative abundance of soil bacterial communities, nutrient availability, and enzyme activities, and may help to contribute to the mitigation of climate change, and sustainability in rainfed areas.