Conservation Agriculture Research Updates - April 2026

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.

This paper looks at ways to address the negative soil, environmental, and productivity issues of the major rice-wheat systems of the IndoGangetic Plains of South Asia that are grown on 13.5 mha and are crucial to food security. They evaluated 8 years of research that looked at farmer practices compared to 6 based on CA principles. They look at yield, economic returns, soil quality factors including chemical, physical and biological components and GHG emissions. They conclude that "CA practices and diversified crop rotations can address issues like falling crop productivity, reduced economic returns, soil degradation, and increasing environmental impacts in northwestern India’s traditional rice-wheat system. However, widespread adoption requires government policies, including C credit payments and guaranteed markets with supportive pricing."

Tillage and residue retention influence carbon storage within soil aggregates and particulate organic matter. This paper studied the effect of CA involving NT with surface residue mulch (NTM) in a maize-wheat system on particulate (POC) and mineral associated organic C (MinOC), C storage within aggregates and acid non-hydrolysable C (NHC) in a sandy loam soil and compared NTM to conventional tillage without residue. Results showed that the NTM improved SOC stocks by 23% more than CT in the 0-15cm. The results also showed that the effects of NTM were brought about by improved aggregate stability and C preservation inside macroaggregates of size >1 mm. They conclude that CA and NT plus residue leads to SOC sequestration in coarse textured soils. 

This paper collected undisturbed soil cores from the FArming System and Tillage long-term field experiment (FAST) near Zurich (Switzerland) to compare conventional. organic, and conservation agriculture systems for soil structure and physical conditions. This site has been under these 3 systems since 2009. The assessed 28 soil chemical and physical properties and related them to root growth, microbial biomass and bacteria and fungi diversity. They conclude that each management system creates contrasting soil physical environments. It also highlights the trade-off between creating a facilitative environment for root growth by tillage and maintaining complex and diverse soil microhabitats for microbes under conservation agriculture.

This paper from Hungary assessed the status of soil in an 18-year-old tillage experiment. looking at physical, chemical and biological properties in 3 tillage systems; No-till (NT), Shallow till (SC), and Ploughing (P). Their results show differences in bulk density (NT>SC) in 0-10cm depth, (NT>P in depths from 10-40 cm. NT had highest SOC in 0-10cm. Soil microbial respiration and abundance and biomass of earthworms was highest in NT. The conclude NT would be a good approach for sustainable soil tillage.

This study looked for the best option for crop establishment, tillage, and rice straw retention over a period of 10 years in a rice-wheat system in the Indian Punjab. Treatments in the main plots included direct seeded rice with ZT (DSRZT), DSR with conventional tillage (DSRCT), DSR with reduced tillage (DSRRT), and puddled transplanted rice (PTR). In sub-plots CT w/o residue (CTW), ZT w/o residue (ZTW), and ZT with residue for wheat. Results showed that bulk density and soil penetration resistance decreased while, plant available water content, infiltration and hydraulic conductivity of the soil increased significantly in DSRZT, DSRRT and ZTW+R compared to PTR and CTW. SOC and aggregation status also increased in DSRZT compared to PTR and CTW. Rice yield was higher in PTR than DSR treatments but wheat yields were higher in ZTW+R than CTW and ZTW..

This long-term research, that was started in 2003 in Denmark, looks at continuous cereal cropping using NT versus moldboard ploughing (MB) combined with a fodder radish cover crop. Soil was sampled at the 0-10 and 10-20 cm depths. Various soil physical properties were assessed. Neither tillage or cover crop affected SOC stock in the 0-20cm depth. NT improved clay dispersibility (CD) and wet stability of aggregates (WSA) more in the 0-10 cm depth compared to plowing suggested as due to lack of disturbance. More results can be found in the paper. They conclude that the positive effects of NT on CD and WSA and the CC's on pore characteristics were more pronounced after 20 years than 10 years and conclude the value of longterm CA experiments.

This paper looks at nitrous oxide (N20) emissions in relation to soil pores under long term CA practices. Soil cores were extracted from CT and NT plots and cover crop (CC) hairy vetch (HV) and no CC (NV) and used for N20 measures. Their results show CT and HV emitted more N20 than NT or NV and for macroporosity, NT and NV increased these more than CT and HV. They conclude that N2O emissions were positively and significantly correlated to relative soil gas diffusivity, CT-derived macroporosity, number of macropores, and fractal dimension.

This South Dakota study assessed the impact of tillage CT and NT); crop rotation: 2-year corn-soybean, 3-year corn-soybean-oat and 4-year corn-soybean-oat-wheat; cover crops (cover crop [CC] and no cover crop [NC]); and drainage (tile drainage [TD] and without drainage [ND]) on soil organic matter (SOM), bulk density, wet aggregate stability (WAS), and field-saturated hydraulic conductivity (Kfs). Soil samples were collected over 2 years from five depths and analyzed for SOM, bulk density, and WAS. NT increased soil bulk density, soil organic matter, and wet aggregate stability (WAS) for the 0- to 10-cm depth but decreased Kfs within the soil profile compared to CT. CC and tile drainage(TD) had minimal impact on SOM, bulk density, WAS, and Kfs.

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 is another study of the impacts of CA but on permanent broad beds (PBB), narrow beds (PNB) and NT flat beds with residue retention on SOC protection within soil aggregates compared to conventionally tilled plots (CT). CA plots had a higher total SOC content than CT ones and improved soil physical properties. Plots under PBB + R, PNB + R and ZT + R had only ~11, 3% and 23% more SOC within silt + clay fraction, respectively, than CT plots (5.85 Mg ha−1). Thus, SOC stabilization within microaggregates inside macroaggregates was the major mechanism, and not the chemical stabilization within silt + clay, of C sequestration under CA. They conclude In this maize/cotton-wheat system that CA on beds or flat are viable options for carbon sequestration, water holding capacity and resistance to erosion.

This paper looks at how CA affects subtropical dryland farming systems in Pakistan. In a field experiment, fallow-wheat (farmers' practice) and the conservation tillage methods minimum tillage (MT), reduced tillage (RT), and zero tillage (ZT) were compared to conventional tillage (CT) in the main plots and the cropping systems sorghum-wheat (S-W) and mungbean-wheat (M-W) to fallow-wheat (F-W) in the sub-plots. They look at SOC, total organic carbon (TOC), microbial biomass carbon (MBC), particulate organic C (POC), and mineral associated organic C (MOC). They show that regardless of cropping system, cumulative CO2 flow was lowest in ZT plots. The CENTURY model confirmed that continuous use of tillage  is a major threat  to soil fertility and production.

Soil health has become a foundation for sustainable goals associated with mitigation of climate change and reversing soil degradation and loss of biodiversity. There is also an array of indicators of soil health but what are the key indicators important for soil health outcomes and ecosystem functioning? This paper proposes and integrated approach to assess soil health.They list important key indicators because of their position in the soil food web and linkages to key soil processes. They recommend that future soil health assessments directly measure soil organisms in conjunction with indicators that reflect key ecosystem functions. 

This study collected soil samples from paired farms that had used CA or conventional tillage (CT) and looked at tillage effects on physio-chemical properties including SOC by soil depth. SOC was higher in CA soils. But higher SOC was measured at depths of 0-10 cm compared to 10-30 cm under CA. In fact, soil depth had significant effects on most soil properties compared to tillage. The paper concludes that CA improved total SOC and its associated fractions, a finding relevant towards understanding effects of land management on carbon storage. However, challenges of competing residue use as feed, mulch, and fuel continued to impede mulching under CA systems.

This paper from Brazil assessed the effects of tillage systems and winter cover crops on soil carbon stocks and maize yields. Tillage treatments were conventional (CT), Reduced (RT) and No-till (NT). Cover crops included vetch, fodder radish, and black oats. Soil sampling occurred 4.5 years after the experiment was started. Samples were taken from 0-45 cm and measured for organic carbon and bulk density. NT had the highest SOC for all cover crops with CT the lowest. Vetch increased maize yield in CT and RT, but had lower C input than radish and black oats because of less biomass. NT systems led to the highest maize yields. Note that maize was not fertilized in this experiment. NT and cover crops was beneficial for environmental and agronomic benefits.

This paper from South Africa explored soil fauna, physico-chemical properties, soil health, and multi-functionality management in 4 different land uses: Conventional (CT), livestock integrated (LA), conservation agriculture (CA) and natural grassland. Results showed that CT favored some nutrients, but soil of both LA and CA had physical and chemical properties indicative of good soil quality like low compaction, low C:N ratio and stable aggregates. Soil fauna abundance was more responsive to management than diversity. Ct where tillage is used had the lowest soil fauna and soil quality due to its disruption compared to no-tillage. They conclude that implementation of sustainable soil management practices that improve soil physical and chemical status will be beneficial for productivity but also for the promotion of important soil fauna, better soil quality and ecosystem multi functionality.

This article looks at how nature manages resources and describes management of a living soil and its productivity using nature's laws to guide crop management. It contends that although tillage was considered necessary for agriculture it is now considered as the cause of soil degradation and violates the laws of nature. Soil tillage over time destroys soil biological, chemical, physical and hydrological properties resulting in soil degradation and lower yields. CA systems that include much reduced or no-tillage with surface mulch and crop rotation on the other hand emulate nature.  and offer farmers, both large and small, productivity, economic and environmental benefits. Te authors conclude that application of CA based management will be needed to reduce the impact of climate change on future food security.

This global review compiles data on the impact of cereal residues on soil health, residue management, residue removing issues, and differences in SH between incorporation or retention on the surface using 113 peer reviewed articles. The review found that both residue retention and incorporation affected soil physical, chemical and biological properties important for soil health.

This paper evaluated the effect of CA management - no-till rice straw mulching on soil health parameters including SOC in the inter-rows of two citrus orchards in Spain. Various soil physical, chemical, and biological  were studied in the top soil layer (0-20cm) over 3 years. Their results showed that rice straw mulch resulted in reduced soil temperature that then resulted in higher crop root growth and increased soil macrofauna development and higher soil enzyme activities. The rice mulch also increased soil macroporosity and SOC levels showing that it enhances soil health in citrus orchards in Spain. However, compacted soils, the beneficial effects of straw mulching on soil health were still limited after three years of treatment.

This paper is from Austria and the objective is to evaluate the soil physical, chemical, and biological effects of 3 different tillage regimes -- conventional (CT), mulch tillage (MT) and No-till (NT) over the long term (1994-2021) sampled in 2002 and 2021. They assessed soil health indicators in the 0-20 cm soil depth (CT soil layer) and below 20 cm. A  “Soil Management Assessment Framework” (SMAF) procedure was applied to assess and compare soil quality using the Soil Quality Index (SQI). MT and NT enhanced soil quality, predominately soil organic carbon (SOC) and soil physical indicators (e.g. water holding capacity, coarse pores). SOC in the 0-20 cm depth increased significantly in NT compared to CT.

This review looks at the challenges of meeting food demands in South Asia complicated by climate change. They contend that CA can help resolve challenges of soil health, climate change, water scarcity, pollution, profitability and human health. This review uses published literature to look at how CA affects SOC and therefore soil health, carbon sequestration and GHG emissions. The results from several studies show CA increased SOC and improved soil health mainly in the surface layer. CA also made a positive impact on nutrient availability. The present gaps in knowledge of soil health assessment and research to fill the gaps are also included in this chapter.

This research from China divided the soil into three aggregate size classes (mega-aggregates), macro-aggregates, and micro-aggregates and evaluated the response of aggregate stability, SOC and microbial communities within aggregates to long-term conservation tillage, which consisted of two tillage methods (conventional tillage and no-tillage) and three nitrogen application rates (105, 180, and 210 kg N ha(-1). Under the NT treatment, the high nitrogen rate increased SOC within mega- and macro-aggregates but reduced the total amount of phospholipid fatty acids (PLFAs) within all aggregates. The paper describes the results for CT and NT with nitrogen rates. They conclude that overall, high nitrogen application under longterm no-tillage protects SOC within mega-aggregates by altering aggregate formation through the microbial communities, providing information that may be useful in developing management strategies to enhance carbon sequestration in agricultural soils.

This paper is based on two long-term experiments started in 2013 in Zimbabwe. There were 6 treatments: Conventional tillage (CT); CT plus rotation (CTR); No-tillage (NT); NT+ mulch (NTM); NT+ rotation (NTR); NT + mulch+rotation (NTMR). Maize was the main crop with treatments using rotation growing cowpea. SOC and soil bulk density (SBD) were taken from 9 depths from 0-100cm. Results show that SOC stocks were higher in NTM, NTR and NTMR treatments compared to NT and CT in the upper soil samples (0-5 and 0-10cm). NT alone had a small negative impact on upper SOC stocks. Cumulative SOC stocks were not significantly different between treatments in the whole 100cm soil profile. NTM enhances SOC stocks but only in the topsoil and showed the highest cumulative organic carbon inputs. Last, results showed thatat least 2 CA principles were needed to increase SOC stocks in these low-nitrogen-input cropping systems.

This paper from India and the NW IndoGangetic Plains assesses the system productivity and soil quality in a CA-based maize-wheat rotation as an alternative to rice-wheat. They compared no-till (NT) with conventional (CT); residue mulch (M+) versus no residue (M0); three N levels, 50 (N1), 100 (N2), and 150 (N3). The soil was sampled from 3 depths down to 30cm. Various soil properties were measured. Available P and K was higher in the M+ plots as expected. NTM+ increased soil microbial biomass C. The highest soil quality index was the NTM+ N3 treatment and the lowest CTM0, N1. Adding maize in rotation with rice improves soil quality.

This meta-analysis collected 14,308 pairwise from 369 global publications to evaluate the effects of different conservation tillage practices (reduced tillage (T), reduced tillage with straw return (TS), reduced tillage with straw mulch return (TSO), no-tillage (NT), no-tillage with straw return (NTS), and no-tillage with straw mulch return (NTSO)) on the activities of 35 soil enzymes. They conclude that conservation tillage improves soil enzyme activity with the combination of NT with residue having good potential for improving soil activity.