Conservation Agriculture Research Updates - April 2026

This paper looks at weeds as responsible for crop losses but also beneficial for ecosystem services. They look at how arbuscular mycorrhizal fungi (AMF) in weeds respond to host identity and CA practices. The study was done in two locations in Southern Africa in both the off season and in-season maize. The diversity of AMF was highest under CA. Their findings highlight that implementing use of mulch and crop rotation to CT and NT positively affected weed AMF colonisation and diversity. The similarity between the off-season and in-season AMF composition of weeds supports the fact that weeds functionally host AMF during the non-crop period. 

This paper evaluated the importance of the third principle of CA, crop rotation and diversification to control weeds, pests, and diseases that can lead to increased yields and profits in Brazil. The objectives of this study were to determine whether grain production systems that employ crop rotation with species diversification are more productive and profitable than double-cropping rotations without diversification and to analyze the revenues and production costs of these cropping systems over a five year period, all under no-tillage and maize-soybeans. They conclude that where crop rotation was used there was higher productivity and profit than maize-soybean systems with rotation.

This paper reports on the use of "Push Pull Technology" (PPT) in maize that they use to control insect pests (stemborer) and parasitic weeds (Striga) in low fertility soils using two farming practices -- CT and CA - in Malawi. Stemborer and Striga infestations were investigated and the suitability levels of two Desmodium species as cover crops. Farmers' perceptions of PPT were gathered through a focus group discussion. The performance of PPT varied significantly between treatments, sites, and years on grain yields and the number of cobs that could be assigned to soil attributes. Results reaffirmed the technology's agronomic benefits in productivity, pest management, plant vigour, and Striga control. The cost of labour was described as a challenge, and research to identify more suitable Desmodium species is needed. They emphasized the importance of Desmodium and Brachiaria as animal fodder to improve the adoption of the technology.

This paper looks at various impacts on water of various sustainable agricultural measures. Straw retention and reduced tillage were mentioned as the most successful measures in arid and semi-arid regions. As such this review looks at these two factors in respect of SOM, soil moisture, soil temperature, soil microorganisms, soil enzyme activity, soil fertility, soil carbon emissions, pests, weeds, soil erosion, water use efficiency and yield under different tillage systems. Straw mulching increased SOM, soil moisture and reduced drought, but can increase pest and diseases and change the microbial community. But straw mulch does enhance WUE and yield. Reducing tillage maintained soil integrity, which is conducive to soil and water conservation.

This is an interesting paper that looks at rotations, one of the pillars of CA in Brazil. Recently rotation has been changed to crop diversity. The most common cropping pattern in Brazil is soybean/second corn crop succession and has led to problems with water and soil conservation and increase in pests and diseases and thus increase in energy use. This study looked at 6 different cropping patterns compared against the one above. Both the traditional and alternate cropping patters provided positive energy balance and efficiency -- they produced more energy than they consumed. But some of the newer systems had higher energy balances and efficiency than the traditional one. The abstract did not mention any differences in pests and diseases though but may have in the paper.

Weeds are a major constraint in Maize in Mexico but best management methods are lacking.  This study evaluated weed dynamics and rainfed maize yield under five weed management treatments (pre-emergence herbicide, post-emergence herbicide, pre-emergence + post-emergence herbicide, manual weed control, and no control) and three tillage methods (conventional, minimum and zero tillage) in 3 agro-ecologies in Mexico. The most effective weed management treatments tended to be similar for the three tillage systems at each site, although weed pressure and the potential yield reduction by weeds tended to be higher under zero tillage than minimum or conventional tillage. No single best option for weed management was found across sites or tillage systems.

This paper addresses issues of transplanted rice, by incorporating conservation agriculture (CA) based crop establishment practices in combination with suitable weed management options to sustain rice productivity. Their experiment had four planting techniques; farmer’s practice (Conventional Transplanting), zero-till direct seeded rice (ZT-DSR), reduced-till direct seeded rice (RT-DSR) (Rotavator single pass) and conventional-till direct seeded rice (CT-DSR) plus five weed management practices using various herbicides, plus hand weeding 20 and 40 DAS and a weedy check. Among various crop establishment methods CT-DSR recorded significantly higher N, P and K uptake by both grain and straw over the rest of the treatments except ZT-DSR during both the years. Based on the results application of pendimethalin pre-emergent followed by chlorimuron + metsulfuron at 20 DAS to the CT-DSR treatment gave the maximum N, P and K uptake by both grain and straw of rice.

This report looks at the potential and opportunities for sustainable development in the high rainfall, hilly areas of NE India where erosion and soil degradation is rampant. It looks at CA as a possible management system to address the issues in this area if India and result in better food and environmental security, reduced cost of cultivation, enhanced cropping intensity, crop diversification and improved soil properties. In this area residue burning/removal, repeated soil tilling, monocropping, low to very low use of organic manure and fertilizers result in soil loss, poor soil properties, low productivity and income. They conclude that large scale research, demonstration and capacity building programs along with adequate policy support is required to promote CA in the region with an ultimate objective of achieving sustainable the Development Goal (SDG) of zero hunger, conserve natural resources, biodiversity and climate resilient agriculture.

This on-farm study in sub-Saharan Africa compared CA based maize-legume cropping systems and CT on soil properties and yield. Treatments were: CT with monoculture maize (CT-M), CA with monoculture maize (CA-M), CA-based maize–common bean (Phaseolus vulgaris L.) intercropping (CA-M+CB), CA-based maize–cowpea (Vigna unguiculata L.) intercropping (CA-M+CP) and CA-based maize–common bean rotation (CA-M–CB). Weed infestation in CA-based maize–legume cropping systems reduced over the years. CA-based maize–legume cropping systems increased soil organic matter, total nitrogen, available phosphorus (Ava.P), and soil water infiltration rate over CT systems.

This paper looks at the transition from conventional flooded transplanted rice to direct seeded rice in NW India. The main challenge in these light textured soils is weeds. This study looked at the removal of nutrients by weeds under three different rice treatments as main plots (DSR-ZT; DSR-CT; DSR-RT) and three sub-plots under the following wheat (CTW-R; ZTW-R; ZTW+R using a happy seeder). Overall, the research study concluded that weeds on an average remove 25.65 % macronutrients (N, P, K) and 51.47% of micronutrients (Zn, Cu, Fe and Mn) in DSR under rice-wheat cropping system.

This article looks at permanent bed planting (PBP) to improve soil quality, soil moisture conservation and stabilize yields of wheat in furrow irrigated systems in Mexico. It also looks at pre-irrigation (wet) and post-irrigation (dry) strategies in Durum wheat comparing conventional tillage and PBP (NT). They used 4 tillage-sowing irrigation and 5 nitrogen treatments over 3 years. The lowest germination was found in PBP-dry and the lowest yield. N fertilization management affected wheat quality, but not wheat yield, possibly due to high levels of soil mineral N available at sowing that were not measured in this study. They suggest research should address reduced plant stands with dry sowing in conservation agriculture to find management options that improve wheat emergence.

This article assesses the effect of rotation in Northern European spring wheat (SW) cropping systems yield, pest and soil health using different tillage methods in a 12-year experiment in Finland. 3 crop rotations were used -- monoculture SW; a two year rotation with SW-rape-SW-barley; and a 4 year rotation SW-rape-barley-pea. Results show a diversified crop rotation improved SW yield by up to 30% in no-tillage and by 13% under plowing compared with monoculture. The yield quantity and quality differences between crop rotations were higher in no-tillage plots than in plowed plots. Weed species in SW before herbicide control was highest in the four-year crop rotation and lowest in the wheat monoculture. For plant diseases, wheat leaf blotch disease severity was lowest in the most diverse crop rotation when wheat was grown every 4th year.. Stem and root diseases became apparent after 6 years of rotation and the disease index was lowest in the most diverse crop rotation. Neither rotation nor tillage affected the control need of wheat midge. Based on our results, diverse crop rotations including cereals, oilseed crops, and legumes increase yield and reduce plant disease severity of spring wheat in Finland, with the magnitude being larger in no-tillage system

This paper looks at the issue of Glyphosate resistant weeds in the soybean crop grown with CA in North America. The rise of Glyphosate resistant weeds in this crop has led to reductions in use of CA in soybeans.They estimate reduced-form and structural probit models of tillage choice, using a large panel of field-level soybean management decisions from across the United States spanning 1998–2016. The first emergence of glyphosate-resistant weed species did not effect tillage practices, though by the time that eight glyphosate-resistant weed species were identified, conservation tillage and no-till use fell by 3.9% and 7.6%, respectively. They estimate an economic value of the proliferation of Glyphosate resistant weeds in soybeans in USA.

This paper looks at how weed density, community diversity, and structure are impacted by different combinations of CA principles (NT, Mulch (M) and Rotation (R) carried out in three seasons and two soil types (clayish and sandy) for maize in Zimbabwe. At the sandy location precipitation did not affect grain yield, but positively affected weed density, diversity, evenness, and richness. By contrast, at the clay location, precipitation positively affected grain yield, but did not modify weed density and evenness, and reduced weed community diversity and richness and also weed density affected grain yield. .

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 the impact of no-till and cover crops on soil health with sunflower following durum wheat in an on-farm trial in Italy. Direct sowing of sunflower following the dead mulch of a roller-crimped hairy vetch was compared with the use of glyphosate to terminate the vetch and control weeds. In this 3-year experiment, they compared three vetch termination stages (early: pre-flowering; Intermediate: beginning of flowering; late: 70% flowering) and three glyphosate rates (Nil, half and full). Vetch biomass increased from early to late termination and the extra biomass resulted in lower weed biomass. Treatments had inconsistent effects on weed diversity and composition, largely determined by the interactions between treatments and seasonal (different years) or local factors. They conclude that targeted timing of roller-crimped hairy vetch in no-till sunflower can result in equal agronomic and economic performances as addition of glyphosate.

This is a new book published in 2022 that looks at many aspects of CA situation, adoption, management, and future outlook in India. The chapters cover the various aspects of crop management such as soil, water, nutrients, weeds, crop residues, machinery, and energy, in a range of environments, including irrigated and rainfed regions. The impact of climate change and the economic considerations behind the adoption of conservation agriculture are also discussed. There are 4 distinct sections as follows:

Part I: Conservation Agriculture: Global Scenario and Status in India - 4 chapters
Part II: Management Options for Higher Resource Use Efficiency -- 6 chapters
Part III: Soil Health and Greenhouse Gas Emissions -- 4 chapters
Part IV: Economics, Adoption, and Future of Conservation Agriculture -- 3 chapters.

This paper looks at rainfed soybean yield gaps in South Africa despite recent genetic introductions and better weed control strategies. Inconsistent rainfall, high temperatures, and soil compaction being the major factors responsible. The benefits provided by including soybean in a maize monoculture production system has been identified, however, crop rotation effects on yield in combination with newly introduced agronomic practices such as no-tillage and crop residue retention are inconsistent. However, less rigorous soil tillage practices alongside greater residue retention can lessen surface runoff and evaporation losses. They conclude more research is needed to understand the soybean yield gap.

This paper investigated how much tillage reduces weed infestation and yield loss, and which systems and weed species are the most affected by tillage suppression. Data was collected from 395 arable cropping systems mainly in France. They used the data and simulated them over 30 years with 10 weather repetitions using the FLORSYS model. Three series were simulated, (1) using the recorded systems, (2) eliminating tillage without any other changes, (3) eliminating herbicides without any other changes. Among the recorded systems, herbicide treatment frequency index (HTFI) averaged over rotation increased when tillage frequency decreased. No recorded no-till system was herbicide-free. The simulations indicated that two CA pillars (diverse crop rotations, cover cropping) were essential to manage weeds while reducing (or eliminating) both tillage and herbicide use. More no-till cropping systems must be investigated to determine whether sustainable no-till herbicide-free systems are possible.

This is an interesting article on ground beetles that are an important component of biodiversity in agro-ecosystems as predators of pests and consumers of weed seeds. Unfortunately, there has been a gradual decline in these insects in Europe. This study looks at the impact of different tillage practices including NT on these beetles. They conclude on balance across multiple studies, greater tillage intensity tends to have a negative effect on abundance, species richness, and diversity of these beetles. The high variability of carabid responses to tillage is also a consequence of various modifying factors such as cover cropping, rotations, and variations in weed control associated with tillage. The paper has a good set of conclusions on this complex question that is worth reading.

This study from India looked at the effects of CA on weeds and yield of a maize-wheat-mungbean system. They showed that CA-based practices with residue retention resulted in significant reduction of weed growth and led to higher yield as well as economic benefits when compared to conventional tillage (CT). The plots under permanent broad bed with residue and 100% N (PBB+R+100N) resulted in significant reduction of weed density and biomass and led to ~27% higher grain yield of wheat compared to CT. 

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 article advocates for integrated weed management rather than relying on herbicides. This study assessed the effects of four IWM systems with contrasting objectives and practices (S2: transition from superficial tillage to conservation agriculture; S3: no-mechanical weeding; S4: mixed mechanical and chemical weeding; S5: herbicide-free; all with 6 year rotations) compared to a conventional reference (S1: herbicide-based with systematic plowing and a 3 year rotation) on taxonomic and functional weed community composition and structure after 17 years of continuous implementation in a winter wheat crop. They found that resulting weed communities in IWM systems were more species rich (species richness from 1.1 to 2.6 times greater) and more abundant (total density from 3.3 to 25 times greater) than those observed in the reference system, and differed in term of taxonomic and functional composition. 

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.