Conservation Agriculture Research Updates - March 2026

This paper from Poland was based on a long-term experiment started in 1999 and evaluated in 2016-2019. The crop studied was faba bean and looked 4 tillage systems; conventional (CT), reduced (RT), strip (ST) and no-till (NT). Over the 4 years there were two favorable years and two with prolonged drought with the weather conditions affecting faba bean yields more than tillage.The highest faba bean seed yield was obtained in 2017 when they ranged from 6.73 t ha−1 in NT to 7.64 t ha−1 after ST and they conclude that NT and ST are the most sustainable. NT provides the best soil protection and
conservation, but in favorable weather conditions, it limits the yield level of faba beans.

Strip tillage is gaining a lot of attention from farmers in the USA so I chose this article from a study in the USA (Alabama following Cotton) for readers of my CA newsletter. The objective of their study was to assess the effects of different tillage practices including strip tillage on soil pore properties. Undisturbed soil columns were collected during two seasons comparing ST with CT. Overall the study showed taht pore morphology can be affected by tillage and seasonal aspects associated with them.

This research paper from China looks at using Strip Tillage to resolve the problems of planting maize where all the residue is returned to the field. They use a Soil-Straw model using a discrete element method (DEM) to study this problem. They propose that a vertical rotation-based straw strip cleaning and soil tillage method with three vertical straw strip cleaning and soil tillage devices combining spring teeth (ST) and rake teeth (RT) design be used. Results showed that the straw cleaning and soil fragmentation rates of the proposed system combination were 97.7 % and 96.4 % and thus provides a new solution for a wide range of straw cleaning for planting maize.

This study from Europe suggests that farmers are reluctant to adopt conservation tillage because of lower yields compared with conventional tillage (CT). But like a couple of other papers in this January newsletter, they look at no-tllage (NT) by itself rather than with residue retention and rotation. Instead they look at ridge-till (RT) and strip-till (ST) as possible alternatives to CT and NT. They looked at 128 studies based on 624 crop yield observations from 21 European countries. They analysed the influence of crop rotation, crop type, texture, climate, tillage depth, residue retention, and duration of experimentation on the relative yield i.e., yield under NT/RT/ST over yield under CT. Their analysis show that NT resulted in 5.1% reduction while RT and ST each led to a 5% increase in crop yield over CT. But the abstract didn't mention the role of residue retention on yield of NT. Although in the paper a whole section was devoted to residue retention.

Depletion of soil potassium as a result of intensive cropping in South Asia is now appearing as a nutrient deficiency. This study looked at CA as a way to alter the soil K pools in soils. They hypothesized that long-term CA will reduce K depletion in soils through recycling and storing soil K. They compared treatments with (CT) and without soil disturbance (strip tillage (SP)) and residue retention at a low (LR) and high rate (HR) over 8 years with 3 crops per year. Soils were sampled at 5 depths and analyzed for K. K levels were always higher in the SP compared to the CT treatments. More crop residue also recycled more K to the soil than lower levels. They conclude that CA with minimal soil disturbance and increased residue retention, resulted in larger K pools in soil and appear to be an effective means for reversing negative K balances in these intensive rice-based cropping systems.

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 paper evaluates GHG emission, global warming potential (GWP), GHG intensity and net SOC variations in rice-mustard-rice cropping systems under CT and strip tillage (ST) on-station. The ST reduced methane (CH4) CH4 flux, GHG intensity and GWP than CT in rice. In mustard ST reduced GHG intensity and GWP compared to CT. There was about 33% increase in N2O emission and 24% augmentation of soil respiratory CO2 with ST compared to CT. There was a 10%  rice equivalent yield increase in ST compared to CT. They conclude that ST can minimize soil C loss, improve net ecosystem CO2 absorption, and reduce GHG intensity and GWP under the rice-mustard-rice system.

The hypothesis for this paper was that rotating rice with maize  using CA (strip-tilled maize followed by unpuddled transplanted rice), or seasonally alternating tillage (SAT; strip-tilled maize followed by fully-tilled, puddled rice with residues retained across rotations) would reduce costs and energy use, increase energy-use efficiency, and reduce yield-scaled CO2-eq emissions (YSE) and total global warming potential (GWP), compared to farmers’ own practices (FP) and conventional full-tillage (CT) under the same rotation in Bangladesh’s coastal region. Data suggested that both CA and SAT can result in a range of positive agronomic, economic, and environmental outcomes compared to FP or CT. But farmers had an aversion to use of all CA practices due to problems hiring labor to transplant unpuddled rice.

This study in Bangladesh looked at two rotations; lentil-mung bean-rice and wheat-mung-rice with strip planting or bed planting, along with residue return, on SOC pools after 1.5 years, compared with intensive conventional tillage (CT) and limited residue return. CT had higher CO2 emission compared with strip planting or bed planting as did high residue return. In the legume-dominated rotation, neither practice sequestered SOC. They conclude that strip planting with high levels of crop residue return can be an effective and quick strategy in either slowing the loss of SOC or improving C sequestration.

This article looks at the issue of weeds and the weed seed bank when converting from CT to CA in Bangladesh intensive rice-based systems. Two rotations were studied: wheat-mungbean-winter rice and monsoon rice-mustard-winter rice. Strip tillage plus residues was compared with CT and no residues. The weed seed bank was determined at several depths. After 2 years, ST+residue had a lower emerged weed count from the weed seed bank. Overall, ST plus 50% residue had a more diverse seed bank than CT without mulch. The majority of weed seeds were amassed in the 0-5 cm soil depth of the ST, while most of them were accumulated in the 10-15 cm layer of the CT.

This paper was chosen because in countries like Bangladesh, 2-wheel tractors are more appropriate for the small land holdings and strip-tillage works well. This article looks at rotary blade design when there is residue. They looked at 4 types of rotary blade with different tip angles but constant rotary speed for wheat and maize in Bangladesh. The research looked at the quality of strip; width of furrow, depth of seed placement but also germination and percent straw cut. Soil cutting depth of strips and seed placement depth was consistent all over the field by the modified blades during wheat and maize sowing. The 15° tip angle blades into 15 cm anchored rice residue (RH15) showed excellent seed germination rate of 96% for wheat and 79% for maize.

This study evaluated a strip-till-one-pass (ST-OP) system on the management of plant residues, soil properties, inputs, and emissions of CA compared to conventional tillage (Ct) with a plough and reduced non-ploughing tillage (RT). As compared with CT, the ST-OP system increased the stability of soil aggregates of 0.25-2.0 mm diameter by 12.7%, glomalin content by 0.08 g.kg(-1), weight of earthworms five-fold, bacteria and fungi counts, and moisture content in the soil. It also decreased soil loss by 2.57-6.36 tons labour input by 114-152 min.ha, fuel consumption by 35.9-45.8 l., and CO2 emissions by 98.7-125.9 kg.per ha per year.

This paper looked at a strip-till one-pass machine that regulated and monitored sowing rate and depth while applying fertilizer. The objective was to assess the accuracy of this wheat drill. They found the accuracy was 97% and 92% in lab and field tests, respectively. Field germination was 88%. The authors conclude that their machine can facilitate planting wheat in accordance with CA needs.

The issue of Potassium (K) deficiency in intensive rice systems in South Asia is increasing. This study evaluated this issue in a long-term CA project. The experiment had three factors; soil disturbance (strip planting (SP) and conventional tillage (CT)), residue retention (low (LR) and high (HR)), K application -- recommended, low and high dose. The experiment started in 2010 and soil sampling done in 2018 and 2020. Overall results indicate that minimum soil disturbance and increased crop residue retention had significant positive effects on cropping system yield and K balance. 

With the residue not being burnt and left as a mulch, there is a need for equipment to plant into this residue. This paper This paper describes a automatic control strip-till piece of equipment to overcome this problem in maize in China. The equipment has an air spring and electric linear actuator that controls the plowing depth straw width control that improves the stability of the equipment. Field tests showed that the straw clearing and soil crushing rates, tillage depth and breadth stability were above 90%. They conclude that the designed equipment would allow conservation tillage  for maize farmers.

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.

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 explores the combined impact of minimum or no tillage and fertilizer regimes on agronomic parameters of cotton–cereal rotations, as practiced by smallholder farmers in Benin in three different climate zones. There were 3 soil preparation treatments - CT, strip tillage (ST) and NT (direct seeding (DS)) and 4 fertilizer treatments. At the three sites NT or DS led to lower below ground biomass and cotton yields compared to CT in the first year of transition to CA where the soils were degraded. Fertilizer regimes affected seed cotton yields differently across sites and treatments, with marginal responses within soil preparation methods, but they contributed to increased yield differences between conventional and no tillage. The results from the first year of this experiment, which is meant to continue for another 5 years, suggest that strip tillage could be a sensible way to initialize a transition, without initial yield penalties, toward more sustainable soil management. Note the paper did not mention the use of residues, an important factor for successful no-till.

This paper from Bangladesh looked at intensively grown (3 crops per year) rice-based cropping systems and various management options. This 9-year study examined various 2 soil disturbance - strip tillage (ST) and conventional tillage (CT); two residue retention levels –15% residue by height (low residue, LR) and 30% residue (high residue, HR) and five N rates (60%, 80%, 100%, 120%, and 140% of the recommended N for a rice-wheat-mungbean system. Rice yields were comparable between the two tillage systems for up to year-6, wheat for up to year-3 but mungbean yield markedly increased in ST from year-1. Introduction of ST increased land equivalent ratio by 26% relative to CT, N use efficiency and partial factor productivity. They conclude that by practicing CA with increased residue retention under strip tillage, the crops had higher N use efficiency, grain yield, land equivalent ratio and annual gross margin in the rice-wheat-mungbean cropping system.

This is another paper looking at the shift from CT to CA and the issue of weeds and in this paper the weed seed bank. Two on-farm CA experiments were sampled at two sites in Bangladesh for the effects of strip planting (SP) and bed planting (BP), plus no-tillage (NT) in one site with increased retention of the residue of previous crops (20% vs. 50%). The conventional tillage (CT) and 20% residue was the control treatment. The weed seedbank in 0–15 cm soil was quantified by assessing the emergence of weeds from soils collected from the field after irrigation i rice and after wheat. The fewest number of weed species (especially broadleaf weeds), and the lowest weed density and biomass was in SP, followed by CT, BP, and NT, with 50% crop residue mulch. Relative to CT, the SP, BP, and NT produced relatively more perennials weeds. They conclude that continuous CA, for 3 or more years, in two rice-based crop rotations, decreased the size of the weed seedbank, but increased the relative proliferation of specific perennial weeds. 

This study looks at the issue of weed control in CA systems that has labor and costs of production problems. This study looked at a CA based rice (direct seeded)-wheat-mungbean cropping pattern over two years of study. The goals were to study the types and distribution of weeds in non-puddled rice and following strip-tilled wheat fields, and to find the most economic way to manage the weeds in both crops. The latter goal included using herbicides. The most most effective treatments involved two herbicides with one applied pre- and one post emergent in wheat and two other herbicides in direct seeded rice also applied pre- and post-emergent.

This paper looks at appropriate equipment for 2-wheel tractors in Bangladesh that allow timely field operations. The specifically look at the design of the blade and furrow openers for strip tillage under different soil types and environments. Compared to shoe-type openers, better seeding depth, uniformity and higher degree of seed coverage were recorded with use of the inverted-T furrow opener with a 65° rake angle. This resulted in better seed coverage in the furrow, a higher emergence rate index, and the highest emergence percentage of maize and mung bean. 

This study looked at CA based tillage with zero, minimum and strip-till tillage in farmer fields for a rice-maize system in Bangladesh run for 5 years. They compared participating versus non-participating farmers conducted by household surveys for 606 farmers. During five years of the trial period, participatory and non-participatory farmers respectively adopted CA-Ts in 12% and 3% of annual cropped areas with overall adoption of 6.6%. Variations in adoption existed between locations, cropping systems, and seasons. Yields either remained unchanged or were higher in the CA-T practices compared to farmers’ practices. Access to critical inputs, knowledge dissemination, capacity building and cropping season influenced the diffusion of CA-T practices.