Conservation Agriculture Research Updates - April 2026

This paper presents results from a long-term experiment from the University of California Division of Agriculture and Natural Resources since 1999. The study site is located in the San Joaquin Valley. 19 years of reduced tillage with cover crops (CTCC) was compared with conventional tillage without cover crops (STNC). Results showed CTCC increased surface soil carbon by 50%, nitrogen by 83%, and air filled porosity 2.5 fold at high water potentials compared to STNC. CCTC respiration rates also increased over 100% under wet conditions, that the authors suggest is due to formation of macropores that become microbial hot spots upon re-wetting that results in accelerated carbon cycling. The authors conclude that "their findings highlight that soil structure–moisture–microbe interactions represent a critical frontier for optimizing conservation agriculture for carbon sequestration, requiring a balanced approach to tillage, organic inputs, and irrigation management to minimize rapid carbon losses. 

This Brazilian paper looks at Crop–livestock–forest integration (CLFI) systems that can enhance soil organic carbon (SOC) content within various aggregate size classes, thereby improving soil productivity and its capacity for atmospheric carbon (C) sequestration.  Treatments included long term CFLI with pasture rotation, CFLI with crop rotation, continuous conventional cropping (CCC), permanent pasture without and with fertilizer. The native Cerrado was used as the check. Results showed that after 23 years of CCC, SOC was reduced by 53%. compared to the Cerrado check. The CFLI treatments had much less SOC loss. They conclude that "the findings highlight the potential of CLFI systems to store carbon in the soil and promote macroaggregate formation, comparable to pastures established for 25 years and the native Cerrado. 

This paper from Texas (semi-arid area) looks at legume and non-legume cover crops (CC) in crop rotations on crop yields, SOC sequestration, GHG emissions, water use efficiency and the farm carbon footprint compared to business as usual (BAU). They also looked at the long-term impact of these practices using the DSSAT model. The results showed that the CC resulted in significant agronomic and environmental benefits compared to BAU. They conclude that "their findings emphasize the critical role of CCs in climate-smart agricultural strategies, highlighting the need to optimize rotations and nutrient management practices to sustainably intensify agriculture in semi-arid regions. 

This research from NW India analyzed data from a 17-year long term experiment that concentrated on crop establishment, tillage and residue management in a rice-wheat system. This cropping system and region of India is impacted by residue burning and GHG emissions. The experiment had 5 scenarios from the traditional system of puddled transplanted rice followed by tillage before planting wheat with all residues removed (Traditional) to NT direct seeded rice (NTDSR), NT wheat (NTW) and 1/3rd residue retention (RR) of both rice and wheat. Among the scenarios the NTDSR-NTW-RR one achieved the highest carbon management index across both the soil layers, indicating a reduced need for carbon management due to higher TOC  compared to the traditional system. They conclude that "reduced or no tillage combined with residue retention in RWS holds substantial potential for increasing carbon sequestration, reducing net GHG emissions, and lowering carbon footprints. Additionally, this practice offers an alternative to crop residue burning, a significant contributor to air pollution in the western IGP."

This is another article in this February newsletter from South America that provides very long term data on CA from a research experiment that considered 5 treatments representing agricultural systems relevant to Paraguay and assessed after 32 years. Treatments in a wheat-soybean system included conventional tillage (CT), reduced tillage (RT), and no-tillage (NT1). In addition, two diversified no-tillage rotations with increasing adoption in the region were included: NT2, composed of black oat–soybean, wheat–soybean, and black oat–soybean; and NT3, consisting of wheat–soybean, vetch–maize, and black oat–soybean. These crop sequences were implemented continuously in three-year cycles over the 32-year study period. The study focused on nutrient stocks, however, consistent relationships between pH and nutrients were observed while pH remained below the minimum threshold recommended for the regional commercial crops . They conclude that "diversified no till farming conserves fertility in low input contexts, but the benefits are limited due to soil acidity. Finally, integrating periodic soil diagnosis with amendments, particularly liming, offers a practical pathway to sustaining production in Paraguay."

This article describes the history of California's Conservation Agriculture Systems Innovation (CASI) that increased the sustainability of agriculture in the San Joaquin Valley of California, by reducing soil erosion, conserving soil moisture, using systems thinking, creating farmer networks, advisors, and researchers since 1998. It used CA management that included reducing soil disturbance for better soil structure and biological activity, retaining biomass on the soil to support soil life, and diversifying crops to enhance biodiversity. They calculate that CASI involves more than 2200 farmers and private sector, university, public agency and environmental groups as partners. The paper describes the benefits of CA in maize, small grains, vegetables, cotton, beans, and melons. They conclude that "reducing soil disturbance for better soil structure and biological activity, retaining biomass on the soil to support soil life, and diversifying crops to enhance biodiversity."

This paper starts out by saying that in Sub Saharan Africa (SSA) tillage and burning of residues is mostly used that causes soil erosion. Maize is also the major crop in smallholder diets. They used the APSIM model to simulate the productivity and protein yield of a variety of intercropping systems involving three crops (maize, cowpea and pigeonpea) under full CA practice relative to conventional tillage (CV) with the same intercropping system. The baseline scenario used daily climate data from 1997-2015 in Northern Mozambique. The results are given in the paper but the Authors conclude that "although under the CA system, there were ng declines in grain yields nevertheless, protein yields and overall productivity remained consistently higher under the CA system.

This paper from China compares the Agricultural Eco-Efficiency (AEE) between conventional tillage (CT) and conservation tillage (CA = no-till plus residue mulch) 2000-2020 using various models. Their results overall show that the AEE under conservation tillage is greater than under CT with both systems exhibiting an initial decline followed by an increase over time. However, there was differences between provinces because of contrasting tillage systems an d trends over time. They conclude "The long-term evolution of AEE in individual provinces is shaped by a combination of geospatial patterns, initial conditions, and other influencing factors. These findings provide valuable insights for policy formulation, the dissemination of conservation tillage, and the advancement of sustainable agricultural."

This long-term field experiment with Winter wheat looked at 3 tillage systems: conventional (CT), reduced (RT), and No-till (NT) since 1995. They collected data on SOC, microbial biomass, and enzymatic activity in four-year crop rotation periods from 2005-2024. There were 3 rotations: winter oil seed rape, winter wheat, pea, and winter wheat.Data was collected from 3 crop depths: 0-10, 10-20, and 20-30 cm. Residues were incorporated in CT, partially in RT and left as surface mulch in NT. Results showed that NT had the highest C-sequestration followed by RT and CT. The weather conditions during the year (abundance of precipitation) influenced crop yields significantly more than the tillage practices with wheat yields and N in grain the highest in CT followed by RT and lowest in NT. NT treatments increased the organic carbon and microbial activity in soils.

This study analyses and compares the economic indicators of conservation reduced tillage (CT) widely practiced in Central Europe with those of conventional ploughing tillage (PT) assessing the effects of CT compared to PT on yields and profitability from 2004-2023. The study covered 83 ha in 10 paired plots (from year 13 onwards, 76 ha in 9 paired plots), including extreme weather conditions and 6 crops. During the transitional period, profit under CT decreased by an average of 11.9% compared with PT, but subsequent periods indicated positive results, 2.3% increase in gross income and 13% higher profit. Over 20 years, material costs for CT plots were 1.9% higher and operating costs were 9.8% lower compared with PT. Their results suggest shifting to reduced tillage is worth it. It would be interesting to have seen the profits if the CA system was used in this comparison. 

This study from NW India using on-farm research explored how different duration's of CA (2, 4, 8, and 12 years) compared to conventional tillage (CT) on SOC, soil aggregation, and system productivity. Results showed that adopting 8-12 years of CA led significant increases in SOC in the topsoil (5cm) and 5-15cmand improved percentages of macroaggregates. But 8-12 years of CA resulted in20-25% reduction in soil inorganic carbon compared to CT. They conclude that enhancing SOC with long-term CA can improve climate-resilient wheat yields in NW India

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.

This paper quantifies the Ecosystem Services from 13 years of using CA practices in a maize-wheat system in India. The treatments were conventional tillage (CT), zero tillage with planting on flat land with residue (ZR + R), permanent broad beds with residue (PBB + R), permanent narrow beds with residue (PNB + R). The CA-based practices recorded higher value of provisioning ES values as compared to CT. The highest economic value of regulating ES was observed under PBB + R, which was 61% higher than that of CT. PBB + R is a better management alternative for better TES while ensuring higher crop productivity than CT. The results can be used to formulate the payment for ecosystem scheme by policy makers.

This report from CIMMYT, Mexico looked at yield and economics of wheat and maize in a 21 year old experiment comparing these two crops on conventional tilled beds to permanent beds with varying residue levels. They also added tied ridges in the furrows to see if they could offset the negative effects of removal or crop residues. Permanent bed planting (PBP+R) plus residue showed better yields compared to the CT beds. PBP plus full residue also yielded better than partial residue but partial residue with tied ridges had equal yields to PBP plus full residue. But treatments with partial residue and tied ridges results in higher net returns because of the value of residue for animal feed, although this is contingent on the market for residues. 

This paper from India looked at the long-term impacts of CA management on water infiltration in soils and also determined the effectiveness of Kostiakov, Green and Ampt, and Philip models in predicting the infiltration rates. Treatments included permanent broad bed (PBB), PBB with residue (PBB+R), permanent narrow bed (PNB), PNB with residue (PNB+R), zero tillage (ZT), and ZT with residue (ZT+R) and conventional tillage (CT). Initial infiltration rate was maximum in PBB+R, which was 111.5% higher than in conventional tillage CT (lowest). PBB+R had the highest infiltration, followed by PNB+R>ZT+R>PBB>PNB>ZT>CT. In other words residue was important for improving infiltration. The Kostiakov model performed the best for predicting infiltration rates.

This another report for a long-term experiment (60 years) from the Triplett Van-Doren No-Tillage and Crop Rotation Experiment established in 1962 in Wooster, Ohio, USA that was designed to evaluate the impact of no-tillage and crop rotation on corn and soybean yields. This experiment is conducted on two contrasting soils, one well-drained and one poorly drained. There were 3 tillage practices; moldboard, chisel and no-till with the residue from the previous crop left in the field and 3 rotations; continuous maize, a 2-year maize-Soybean, and a 3 year maize-forage-forage. Crop rotation was the main driver of long-term crop performance, with the most favorable responses observed when forage crops were included in the cropping system at both sites. Note the forage crops contained mixtures with legumes. The paper contains a lot of interesting data. They conclude that " By evaluating long-term trends, we found that no-tillage can be viable even in clay soils under temperate climates when perennial crops are included in the rotation system. Our results demonstrate that longterm crop yields can significantly benefit from the implementation of both practices adopted together in cropping systems."

This paper presents some of the data from  a family farm in Ohio, one of the oldest continuous NT and cover crops adapted farms in Ohio since 1971. The objective of the study was to assess the effects of no-till (NT) management over 0, 6, 20, and 35 years in a rainfed corn-soybean system, incorporating cereal rye as a cover crop, on soil organic C (SOC) sequestration and total N accumulation across different pools. The results show a significant increase under NT compared to conventional for SOC, total N, microbial biomass C, active C, passive C, particulate organic C and N. They conclude that "long-term NT consistently facilitates SOC sequestration and total N accumulation in different pools, with these benefits distributed non-linearly across distinct SOC and total N pools at the 0-15 cm depth and linearly at the 15-30 cm depth in rainfed corn-soybean systems."

This is another article from the Central Valley of California that assesses 20 years of conservation agriculture management that looks at soil physical, chemical and structural properties comparing reduced tillage with cover crops with conventional tillage without cover crops. In brief, the CA management achieved dynamic equilibrium characterized by fundamental shifts in carbon stabilization pathways. Water stable aggregates also exhibited 136% greater stability with CA than with CT. This paper discusses the implications of these differences. They conclude "This mechanism shift represents a new soil system equilibrium that maintains enhanced functionality and continued carbon sequestration potential in Mediterranean agricultural systems."

This research looked at long-term adoption of residue retention on soil-water and temperature for wheat grown under CA in both a field experiment and crop model simulation using the APSIM (Agriculture Production System Simulator) model. Two tillage practices were NT + Residue retention (NT+R) and CT with residue incorporation (CT+R). The results indicated that the model accurately simulated crop phenology, leaf area index, above ground biomass, and grain yield under both tillage treatments. Soil water content, transpiration and drainage were higher in NT+R compared to CT+R. Evaporation and soil temperature were higher in CT+R. The authors were happy with the APSIM model for identifying the effect of tillage and residue on wheat yield components. 

This 10-year study from India compared 2 conventional tilled (CT) puddled transplanted rice followed by either CT wheat or NT wheat with 6 different NT Direct seeded (DSR) rice followed by NT wheat treatments. Details can be found in the abstract or full paper since two treatments also used Sesbania (brown manure) in the system and 2 used an additional mung bean crop. A summary of the results showed that the NT wheat treatments were better than the CT wheat but CT rice had a higher yield than DSR rice. The overall rice-wheat system also was better than the traditional system despite the lower rice yield. Soil fertility, SOC, soil health, GHG emissions, and profitability were better in the CA systems compared to the CT one. The recommended that more research is needed to control weeds, nutrient needs and water management to improve the DSR treatment.

This paper from Ohio State University's Triplett-Van Doren long-term tillage and crop rotation experiment (one of the oldest NT experiments in the World) looked at the temporal dynamics of soil N and C pools in a maize growing season, in a 55 year old tillage and crop rotation experiment. Tillage treatments were no-till (NT) + residue, Chisel-till (CT) + 30% residue and moldboard till (MT) - residue incorporated. There were 3 rotations: continuous maize, maize-soybean (2-year rotation), and maize-forage-forage (3 year rotation). Their results suggest that crop diversification with perennials enhances soil C and N; NT has stronger effects in clay loam than silt-loam soils; and although C and N pools vary seasonally, long-term management effects persist throughout the growing season.

This paper starts by saying conventional agriculture is labor, energy and water inefficient and so reports of experiments to identify more sustainable, productive and efficient crop production in a maize-wheat-mungbean system started in 2009-10 and assessed in 2018-19 to 2019-20. Treatments included CA-based bed planting methods such as permanent narrow, broad and flat beds with and without retention of crops residues and 75% and 100% of the recommended dose of nitrogen (N) were compared with conventional tillage (CT) treatment. Results show that adopting the CA practice involving a permanent broad bed with residue using 100% N in this maize-wheat-greengram system was more productive and efficient for nutrients, water, and energy.

The authors mention that there are 3.5mha of CA in India but little data on the effects of CA on soil nutrient dynamics like N, P, and S. They have a nine year study on these nutrients in a maize-wheat cropping pattern that compares CA with conventional methods. Results show that CA and N addition significantly enhanced various soil chemical properties and microbial biomass compared to CM for N, P and S and concluded that "These findings contribute crucial knowledge for sustainable development by offering valuable perspectives on N, P and S management strategies."

This paper reports on the long-term effects of different tillage practices and crop residue management on soil biological and physical health using winter wheat and a fodder radish cover crop. The experiment started in 2003 and samples taken in 2021. There were three tillage treatments: direct sowing (NT), harrowing to 10 cm H), and moldboard plowing to 20 cm (MP). Residue was either removed or left in the plots. The biological soil measures were two fatty-acid biomarkers arbuscular mycorrhizal fungi (AMF)and glomalin-related soil protein (EE). Soil physical indices were water stable aggregates (WSA) and five soil pore characters and SOC. CA practices increased AMF biomass and harrowing and NT resulted in stratified SOC. Residue increased SOC levels. They conclude that their study identified the significant role of AMF in maintaining soil health.

This paper utilized bibliometric analyses to map the conceptual and intellectual structure of soil health research from 1996-2021. They reviewed 984 peer reviewed papers that they divided into 3 major research clusters. The analysis revealed critical gaps, including limited integration of pedological modeling to quantify ecosystem services and insufficient long-term studies on conservation agriculture. They recommend that interdisciplinary collaboration among agronomists, microbiologists, policymakers, and climate scientists to align soil health metrics with global targets providing a roadmap to integrate soil health into climate-smart land-use policies.