Conservation Agriculture Research Updates - April 2026

Groundwater resources in the Indo-Gangetic Plains of India have diminished in the high productivity rice-wheat systems of this region. It is vital that new alternative crop establishment and irrigation methods that do not rely on the conventional puddled transplanting method (PTR) are found. This paper assesses the impact of combining CA with sub-surface drip irrigation (SSD) referred to as CA+, at different nitrogen (N) doses on physiological performance, crop yield, irrigation and nitrogen use-efficiency, as well as farm profitability of rice in the north-western IGP of India. The results showed that the PTR plots produced 15% and 11% higher grain yield than CA and CA+ systems, respectively, even at 100% RDN, due to a significantly higher number of fertile tillers. But the CA+ SSD plots reduced irrigation water use by 1.5-2.0 times compared to CA and PTR plots and provided benefits in improved WUE, NUE, and crop yield. They suggest that future research should focus on identifying ideal rice cultivars suitable for CA+ systems and determining the optimal specifications for drip lines and emitter discharge rates for diverse water-scarce agro-ecological conditions.

This review paper from Bangladesh looks at the inclusion of legumes in rice based cropping systems where there is increased risk due to water, energy, labour and capital scarcity, which are exaggerated due to the effects of climate change. There is also a loss of soil health, groundwater depletion, and reduced water and land productivity that threatens food security. They suggest that CA with inclusion of legumes may be a solution. They list some of the benefits of including legumes in rice-based systems. They conclude that sustainability improvements can be made by researching the inclusion of legumes in rice systems of Bangladesh.

This is another paper from the Indian Himalayas that discusses degradation of environmental quality, water systems, and soil resources by present farming practices and the use of CA as an alternative option. The aim was to evaluate the effect of CA and weed management (WM) practices on carbon dynamics and biochemical properties of soil. The CA levels varied from conventional agriculture to partial CA (pCA1, pCA2, and pCA3) and full CA, while WM had three levels consisting of chemical control, integrated weed management, and weedy check. Results showed SOC and labile fractions of C were highest under full CA, but there were no differences for organic carbon. Full CA also had higher dehydrogenase and alkaline phosphatase activity than conventional agriculture. Full CA had the highest soil quality index and conventional the lowest. WM showed herbicide the best but little difference for weedy check or IWM.

This paper looks at nitrogen (N) rates and residue management in a wheat crop on soil biological and chemical properties. Different combinations of N fertilizer rates, tillage, and residue management practices for wheat were investigated. N was 75 and 10% of recommended. Tillage treatments included CT, rotoseeder (RS), Happy Seeder (HS) with various residue treatments with rice residue removed  or retained R0, R50(50%) and R100. The results showed that N-100 and HS +R-100 increased wheat yield, chemical and biochemical properties except polyphenol oxidase and peroxidase. The HS picks up loose rice residue before planting no-till and then placing the residue on the soil as a mulch and so allows seeding into loose residue using fixed openers. 

This paper used 9 treatments of tillage and residue management practices in fixed plots for 5 years on crop productivity and soil biological parameters in a rice-barley cropping system. Results show that shifting from puddled transplanted rice to direct seeded rice resulted in a yield penalty, but did not mention the issue of weed competition. The NT barley (NTB) with residues yielded better than just NTB. The best system productivity was with non-puddled TP rice and NTB (UPTR-NTB+R) with residues. Biological parameters were were significantly affected by different management practices. The same system also provided better soil health.

In Eastern Gangetic Plains CA management can improve cropping system performance but farmers adoption is low. This paper looks at CA-based crop establishment practices combined with alternative crops that could improve the whole cropping system in terms of productivity, profitability, and nutritional security over a longer time. 5 maize-based under CA management are compared with conventional tillage (CT) rice-wheat (RW). Results show that CA practices improved maize equivalent yields, protein, water productivity, and yield relative to CT RW. Labor and costs of production were also less under CA resulting in better net returns. They conclude that while cropping system performance can be improved by applying CA-based management in RW systems, diversifying to maize-based systems in combination with CA may sustainably improve smallholder productivity and profitability while reducing some of the constraints to introducing CA in rice-based systems.

This a second paper in this newsletter on potassium, an issue that has arisen in the intensive rice-wheat systems of the IGP. It was once thought that soils of this area had sufficient K for many years, but with high yields and removal or burning of residues has resulted in K now being a new nutrient deficiency. This paper sampled a long-term field experiment after 11 years to assess the effect of long-term cereal-based CA on K supplying capacity in soil of North-West India. This experiment had 6 scenario cropping systems with rice, wheat, maize, and mungbeans and compared the CA lots with the conventional system. The full CA based scenarios maintained significantly higher available K compared to the check treatment. The best scenario used rice-wheat or maize-munbean with sun-surface drip irrigation. The paper highlights the potential of long term crop residue retention under CA for improving and maintaining K supply to crops.

This study investigated various Climate Smart agriculture (CSA) practices on earthworms and soil physico-chemical properties in R-W systems in IGP area of South Asia using a 10 year established experiment. There were 5 scenarios with one the farmers practice (transplanted rice- tilled wheat) used to compare with the other 4 CSA ones. The other 4 CSA ones had rice-wheat-mungbean with flood irrigation (FI) and subsurface drip (SDI) and maize-wheat-mung bean with FI and SDI. Earthworms were absent from the check scenario whereas the 4 CSA scenarios over 10 years increased EW density and biomass. The maize based CSA's had more EW's than rice based ones and Drip systems had higher numbers than flooded treatments.  They conclude that CSA-based scenarios, in particular, maize-based scenarios using SDI, improved EWs' proliferation, SOC, and nutrients storage (in soil and EWC) and showed a better choice for the IGP farmers with respect to C sequestration, soil quality, and nutrient availability.

This is another fungal community paper affected by management practices from India. It also looks at soil chemical and physical properties. It looked at various climate smart agriculture (CSA) scenarios based on CA and compared with CT in rice-wheat systems. There were 6 scenarios with CT, NT and +/- mungbean in rice-wheat and maize-wheat systems. The first 4 scenarios were flood irrigated and the last two with a subsurface drip with N as fertigation. Soil samples from 0-15cm were taken for fungal community composition. The data showed a higher Shannon diversity index of 1.47 times and a Simpson index of 1.12 times in maize-based CSA scenarios (ScIV and ScVI) compared with rice-based CSA scenarios. Soil physical, chemical, and biological properties were found better under CSA-based practices, which also increased the wheat grain yield and system yield and hence play an important role in sustaining soil quality/health.

This paper reports on the rice-maize system in Bangladesh, an expanding system in this country. Traditionally, this systems cultivates puddled transplanted rice followed by tilled maize. This is labor intensive, reduces soil health and is less profitable. As such, a field study looked at conservation agriculture (CA) based tillage and crop establishment (TCE) techniques and residue management practices on the physical, chemical, and biological properties of soil along with crop productivity and the profitability of rice-maize systems in the sandy loam soil of Northwest Bangladesh. The authors concluded that CA could be an appropriate practice for sustaining soil fertility and crop yield under R-M systems in light-textured soils or other similar soils in Bangladesh. 

This study used an integrated network to show how the reduction of tillage (RT) intensity influenced invertebrates (such as rice pests and their predators), pathogens and weeds, that led to an impact on rice yield.This two year study showed that major rice pests, common diseases, and the density of weeds declined or were controlled by RT. The diversity and richness of pest predators increased in rice fields where RT or NT was used and yields increased gradually. The authors conclude that RT is beneficial for the protection of rice from various pests, and improves the sustainability of the agroecosystem and rice yield in southern China.

Farmers practice with CA varies considerably in different environments, farming systems, and the intensity of farmers management. This paper addresses this variability by developing an efficient tool to evaluate the cost-benefit of CA, to inform agricultural policymakers and development priorities to facilitate expanded use of CA under appropriate circumstances in the R-W system in South Asia. They used a 9-year experiment in the Eastern IGP to parameterize the EPIC model to simulate five CA and conventional managements. Geospatial and farm surveys information was used to parameterize the model at the regional scale. They conclude that yield gains from CA are widespread but generally low under current management regimes.They also suggest that farmers interested in CA to apply optimal management practices appropriate for their environment.

This study analyzed 84 on-farm trials comparing CA-based practices (CA) with farmers' conventional ones (CT) in rice-wheat systems of the Eastern Tarai region on Nepal. The objectives were to investigate crop and cropping systems productivity, profitability, yield stability, irrigation (WPi) and total water productivity (WP(r+i)), and fertilizer-use efficiencies of three CA- and one CT-based practice in R−W systems. The CT system was puddled transplanted rice (PTR) and tilled wheat (CTW). The three CA based systems were 1) PTR - ZTW; 2) Direct seeded rice (DSR) -ZTW; and 3) unpuddled transplanted rice (UPTR) - ZTW. There were no significant differences in rice or wheat yields between CT and CA treatments, but significant reduction in production cost due to reduced labor use and increased net gain (188−223 USD ha−1) in all CA-based R−W systems. DSR−ZTW showed the highest yield stability and net profit, demonstrating its adaptability in the region. CA based systems reduced production costs and increased farm profits, saved energy and water, increased land and labor productivity, and improved food security.

This paper looks at CA as a possible system to reduce residue burning in India by assessing the optimum residue levels for CA. It used the APSIM simulator model to analyze 37 years of diverse CA scenarios for yield, sustainability and carbon footprints in rice-wheat cropping systems (RWCS). The analysis indicated that the maximum system productivity was under the highest residue (HR) compared to conventional tillage with stable yields achieved under CA. SOC was predicted to increase by 30-95% with CA with higher sequestration rates and water productivity was highest with HR. They conclude the APSIM model is efficient in capturing CA effects in South Asian RWCS and that the adoption of CA results in greater and stable yields, higher water productivity, and more carbon capture over the long term, while reducing production costs.

This paper starts by saying "Burning of agricultural residues, cultivation of single crop varieties such as rice and wheat, and traditional soil tillage practices collectively contribute to the degradation of environmental quality, water systems, and soil resources. They describe CA as a viable alternative including weed management (WM). CA treatments varied from CT, three partial CA and a full CA. WM varied from Herbicide, Integrated WM and weedy check. They measured SOC, labile carbon fractions, total organic carbon, and several biochemical indicators of soil health. Results showed that CA had higher SOC and labile carbon fractions, and biochemical indicators resulting in a higher soil quality index value.

This is a second paper reporting on the issue of declining water tables and using drip irrigation (sub-surface drip - SSD) and CA to counter this problem but substituting maize for rice. This two-year field experiment in maize, under an ongoing CA-based maize-wheat system, evaluated the complementarity of CA with SSD irrigation with two CA interventions– CA+ (residue retained CA + SSD), and PCA+ (partial CA without residue + SSD) - at different N rates (0, 120 and 150 kg N ha-1) in comparison to traditional furrow irrigated (FI) CA and conventional tillage (CT) at 120 kg N ha-1. Overall, compared to the FI-CA and CT, SSD-based CA+ and PCA+ saved 54% irrigation water and increased water productivity (WP) by more than twice. CA coupled with SSD provided tangible benefits in terms of yield, irrigation water saving, WP, NUE and profitability.

This paper from Bangladesh had two 5-year field experiments on two different soils to measure the effects of CA on soil microbial populations. The first, on non-calcareous soils had two tillage; minimal (MT) and conventional (CT), three cropping patterns involving rice-rice with lentil, wheat and mustard LRR, WRR and MRR, and plus and minus residue. The second experiment on calcareous soil had three tillage; strip-till (ST), NT and CT and two previous crop residue treatments - High (50%) and Low (15%). Non-calcareous soils had higher fungal populations with higher microbial biomass carbon but lower nematode and bacterial populations compared to the calcareous soils. In non-calcareous soils, MT had higher microbial populations than C at 0-7.5cm but no difference below that. LRR had more microbial populations then MRR and WRR. In the calcareous soil, NT and ST had higher microbial populations than CT. the more residue left on the surface resulted in higher microbial populations.

Upland rainfed rice in Madagascar is usually planted on tilled soil as seed and not transplanted resulting in serious weed issues. This field experiment looked at a no-till system with the legume Stylosanthes (NT) managed as a living mulch and compared with the tilled (CT) system. In addition two fertilizer treatments were added; organic manure (F1) and organic combined with mineral fertilizer (F2). Weeds flora were documented and the affect of weeds on rice yield assessed by having weedy and weed-free plots. The effect of the cover crop on rice yield was also assessed using weed-stylosanthes-free plots. Results showed that NT suppressed the dominant grass weeds leading to a decrease in total weed biomass. Rice yield was significantly higher in NT than in CT. The living mulch reduced rice yield by 14% but it remained significantly higher in NT than in CT. The addition of mineral fertilizer to the organic manure had a positive effect on rice yield but only in weed-free conditions.

Crop residue burning in the intensive rice-wheat systems of the Indo-Gangetic Plains is a traditional practice but one that deteriorates the soil and environment including air quality. This paper looks at the impact of residue burning and excessive tillage on soil biological properties such as SOC, microbial biomass carbon (MBC), Soil Respiration (SR), Bradford reactive soil protein (BRSP), nitrogen mineralization rate and microbial community structure at two soil depths 0-15 and 15-30 cm. Four different burning treatments included with and without burning residues and tillage and no-till (NT). Results indicated that crop residue burning and tillage pose significant impact on soil biological parameters and soil microbial community especially at surface soil. They conclude that no burn and NT is a more ecologically sustainable system for soil biology. 

This paper investigates the root system dynamics of summer mung bean under different conservation agriculture practices. The best root properties were recorded in the Soybean (permanent bed; PB)-Wheat(PB)-Summer mung (PB)(+Residual; +R) based cropping systems, followed by Maize(PB)-Wheat(PB)-Summer mung (PB)(+R), while, the lowest values of above parameters were recorded in the Puddled Transplanted Rice-Conventional till (PTR-CT) Wheat-Summer mung (-R). The mung yields and yield components were also the highest in the Soybean-wheat-mungbean system listed above. The yield of summer mung bean increased when residues were retained. They conclude that the inclusion of summer mung in soybean-based cropping systems may substantially improve the root architecture and soil quality and increase crop yield under conservation agriculture.

This study looks at direct seeded rice (DSR) and NT DSR and the issue of weed control. Field experiments were conducted involving conservation agriculture (CA)-based DSRs compared to puddled transplanted rice (PTR) and weed control/herbicides treatments to appraise weed interference and productivity under an eight-year old CA-based rice-wheat system (RWS). All DSRs encountered more weeds than PTR. A double ZT system without residue had the highest density and dry weight of grassy weeds, but a triple ZT system without residue had the highest density and dry weight of broad-leaved and sedge weeds. However, a triple ZT system adding three crops residues reduced weed interference significantly and led to higher rice yield. The use of various herbicides significantly reduced all weeds. They recommended that the triple ZT system with rice, wheat and mungbean residues (C5) combined with application of herbicides be used in similar agro-ecologies in the IGP.

This is paper on the rice-wheat systems of South Asia, a system where its sustainability is questioned. The paper looks at the soil physical properties and carbon pools in a 10-year CA experiment. The treatment that had triple NT in all three crops (CA5) -- rice-mungbean-wheat - with residues left on the surface resulted in higher soil aggregates than conventional tillage - puddled transplanted rice - tilled wheat. Soil infiltration rate, sorptivity, and saturated hydraulic conductivity, yields and net returns were also significantly higher in CA5 than in CT. They conclude that CA-based rice–wheat–mungbean system (CA5) would be an alternative to conventional PTR-CTW system in the Indo-Gangetic Plains of India and in similar agro-climatic situations of South Asia. 

This paper looks at practices to reverse declining soil fertility resulting from excessive tillage and crop residue removal, while decreasing production costs and increasing farm profits in two sites in Bangladesh. Crop establishment methods included strip planting (SP), bed planting (BP), and conventional tillage (CT). Residue levels used were high (HR) and low (LR). The SP and BP of non-rice crops were rotated with non-puddled rice establishment; CT of non-rice crops was rotated with puddled transplanted rice. In the legume-dominated system (rice-lentil-mung bean), lentil yields were similar in SP and CT, while lower in BP in crop season 1. A positive effect of high residue over low residue was apparent by crop season 2 and persisted in crop season 3. In crop season 3, the lentil yield increased in SP and BP compared to CT. In the cereal-dominated system (rice-wheat-mung bean), significant yield increases of wheat in SP and BP over CT, and of HR over LR, were found by crop season 3 but not before. Rice yields under CA practices (non-puddled and HR) were comparable with CT (puddled and LR) in both systems.

This book chapter reviews the various practices researched and recommended for farmers in eastern IndoGangetic Plains of India for sustainable intensification of rice based cropping systems grown in this part of India. Ca and direct seeded rice, zero-tilled rice, mechanically transplanting improved water use efficiency, soil health and system productivity. Increasing cropping intensity from one crop to 2 or 3 per year was also possible with diversification, using short duration rice varieties, climate resilient other crops  improved management practices and appropriate mechanization. Other practices including infrastructure for irrigation, storage, marketing, value chains, and efficient extension systems also need to be developed. Some important agronomic practices include integrated use of fertilizers, soil mulching, optimal use of irrigation water, robust seed systems, crop rotation, integrated weed management (introducing new molecules and promoting mechanical weeding), using an integrated farming system approach, and policy support for small and marginal households.

This paper addresses the issue of declining water tables and increases in soil salinity in irrigated drylands. The paper assesses the potential of CA practices - water saving irrigation, water quality, and nitrogen rates to sustain rice-wheat (RWS) and cotton-wheat cropping (CWS) systems. The study included mixed-method approaches of two years of field experiments, and soil profile and groundwater salinity simulation using Hydrus-1D model, and multi-criteria trade-off analysis for the holistic assessment of alternative innovations in RWS and CWS. Fourteen sustainability indicators computed from experiments and simulation were compared to evaluate the sustainability of those cropping systems and to reveal the potential of those practices for improving sustainability. This study showed the importance of agronomic, soil, and water management practices for minimizing soil salinity and demonstrated the role of CA in sustainable agricultural production particularly under CWS in salt-affected irrigated drylands.