Conventional Soil Tillage Research Articles

Characterization of soil pores in strip-tilled and conventionally-tilled soil using X-ray computed tomography

Changes in soil pore size distribution and connectivity can affect contaminant transport. Climate, soil type, and agricultural management practices can influence these characteristics. Conservation tillage practices, such as strip tillage, have been promoted as agricultural management practices that can help reduce soil erosion and nutrient loss in runoff. However, limited information exists in the literature on the effect of strip tillage on soil pore characteristics. Thus, the objective of this research study was to assess the effects of different tillage practices i.e., conventional tillage (CT) vs. strip tillage (ST), on soil pore properties and quantify change in soil pore characteristics as a function of season. Undisturbed cylindrical soil columns (150 mm diameter and 640 mm length) were collected from a field in Alabama, USA planted with cotton (Gossypium hirsutum L.) under ST and CT treatments during two seasons i.e., fall 2021 and spring 2022. Soil cores were collected from CT and ST portions of the field, in the fall, following cotton harvest and before planting a cover crop (season 1), and in the spring, after the cover crop had matured (season 2). X-ray computed tomography was used to scan the soil cores and quantify soil pore characteristics. Results show that the ST treatment had significantly (p < 0.05) greater macroporosity values, network density, macropore length density, and interconnectivity compared to the CT in season 1. This was attributed to ST being a minimally disturbed treatment: thereby, it has a better chance of preserving cracks and biological activity as compared to CT, which is more prone to destruction of large macropores. The pore properties also showed a drastic decrease in values during season 2, especially for the top 200 mm of the soil profile in response to rainfall induced soil reconsolidation in both the tillage systems. Overall, this study showed that pore morphology can be affected by tillage and seasonal aspects associated with them.

Effects of transitioning from conventional to organic farming on soil organic carbon and microbial community: a comparison of long-term non-inversion minimum tillage and conventional tillage

The combination of conservation tillage (non-inversion and no-till) with organic farming is rare due to weed problems. However, both practices have the potential to improve soil quality and increase soil organic C (SOC). This study investigated the changes in SOC, microbial biomass, and microbial composition during the transition from conventional to organic farming (from 2014 to 2020) in a long-term tillage trial established in 1999. Non-inversion minimum tillage to a depth of 10 cm (MT) resulted in SOC stratification, whilst conventional soil tillage with 25-cm-deep mouldboard ploughing (CT) maintained an even SOC distribution in the plough layer. After 12 years of contrasting tillage in 2011, the uppermost soil layer under MT had a 10% higher SOC content (1.6% w/w) than CT (1.45% w/w). This difference became even more pronounced after introducing organic farming in 2014. By the fall of 2020, the SOC content under MT increased to 1.94%, whilst it decreased slightly to 1.36% under CT, resulting in a 43% difference between the two systems. Conversion to organic farming increased microbial biomass under both tillage systems, whilst SOC remained unchanged in CT. Abundances of total bacterial and Crenarchaeal 16S rRNA and fungal ITS genes indicated shifts in the microbial community in response to tillage and depth. Fungal communities under MT were more responsive to organic farming than bacterial communities. The improved soil quality observed under MT supports its adoption in both organic and conventional systems, but potentially large yield losses due to increased weed cover discourage farmers from combining MT and organic farming.

Synergy between Zeolites and Leguminous Cover Crops Improved Olive Tree Performance and Soil Properties in a Rainfed Olive Orchard

Soil degradation and climate change are threatening the sustainability of Mediterranean olive orchards, typically grown under rainfed conditions and conventional soil tillage. Thus, implementing sustainable soil management practices is crucial to preserve soil health and mitigate the negative effects on plant performance. In this study, we assessed the effects of conventional tillage (T), an early maturing and self-reseeding annual legume cover crop (LC) and its combination with natural zeolites (ZL) on plant physiological performance, tree nutritional status, crop yield, and soil physicochemical and microbiological properties. Although both LC and ZL enhanced the photosynthetic activity, tree nutritional status, soil moisture and olive yield relative to T, ZL was clearly more efficient at improving some soil health indicators, namely at the 0–10 cm soil layer, once soil acidity decreased and Kjeldahl N, extractable P and B, cation exchange capacity and microbiological activity increased, as evidenced by the higher concentrations of easily extractable and total glomalin-related soil protein, microbial biomass carbon, microbial biomass quotient, and actinomycetes. Therefore, using natural zeolite with leguminous cover crops appears to be a promising strategy of sustainable soil management in rainfed olive orchards, as it is able to provide numerous ecosystem services.

Earthworms increase soil greenhouse gas emissions reduction potential in a long-term no-till Mollisol

Earthworm activity and plant residues in the soil can strongly influence soil organic carbon (SOC) dynamics. However, studies on how earthworms, especially epigeic and endogeic species alone or together, affect the main soil greenhouse gas (GHG) emissions (CO2 and N2O) and SOC under the long-term no-till (NT) and conventional tillage (CT) in Mollisols in Northeast China are unclear. The effects of two different species of earthworms (epigeic, Eisenia nordenskioldi; endogeic, Metaphire tschiliensis) on the soil GHG emissions and the SOC content were studied in NT and CT soils in a 337-day mesocosm experiment. The presence of earthworms enhanced the soil cumulative CO2 and N2O emissions in both NT and CT soils, and the soil GHG emissions (expressed in terms of the global warming potential, GWP) were increased by 20.43 %–42.99 % in NT soil and by 0–55.62 % in CT soil, respectively. Compared to E. nordenskioldi, the presence of M. tschiliensis (endogeic species) significantly increased soil GHG emissions. Earthworms in NT soil induced less soil GHG emissions than those in CT soil. The presence of earthworms did not increase the SOC content in CT soil but significantly increased the SOC content in NT soil. Our study suggests that earthworms in the long-term no-till soil can contribute to the reduction of soil GHG emissions. This research helps to understand the effects of different ecological categories of earthworms on soil GHG emissions and SOC dynamics under different tillage systems and to mitigate soil GHG emissions.

Water-stable aggregation among untilled and intensively tilled soils with similar contents of aggregating agents in central Ohio, USA

Organic carbon (OC), permanganate-oxidizable carbon (POXC), and autoclaved citrate-extractable (ACE) proteins are utilized as soil quality indicators due in part to their positive relationships with water-stable aggregation (WSA). Tillage-induced losses of WSA are oftentimes attributed to decreases in these soil constituents. The objective of the present study was to explain differences in WSA existing between tilled and untilled cropland soils through comparing the soils in terms of these and other aggregating agents. We examined WSA and a suite of related properties on conventional tillage (CT) and no-tillage (NT) soils of an Epiaqualf-Argiaquoll association along a low-relief hillslope in central Ohio, USA. Overall, WSA was strongly correlated (r > 0.7, P < 0.05) with OC, POXC, and ACE proteins, but when concentrations were similar between NT and CT soils for these constituents, most notably at the toeslope position, WSA was consistently greater for the NT soil. Statistically controlling for the effect of these individual WSA covariates did not change this result. Results suggest that heightened WSA for the NT vs. the CT soil may be due to the greater water repellency of the former when other aggregating agents are equivalent between tillage regimes. These findings suggest that soil quality evaluators should measure WSA directly rather than rely on inferences based on organic constituents, especially when working with CT soils from poorly drained, depositional landscape positions.

The Influence of Short-Term Tillage, Compost, and Beneficial Microbes on Soil Properties and the Productivity of Wheat and Cowpea Crops

Tillage systems comprise physical, chemical, and biological modification processes that influence soil properties. Soil cultivation aims to create favorable conditions for the development and growth of crops, as evident in their yields. Three growing seasons (winter 2019/2020 (wheat), summer 2020 (cowpea), and winter 2020/2021 (wheat)) were studied in field experiments in Sidi Salem, Kafr El-Sheikh, Egypt, to investigate the effects of soil tillage and the application of organic and beneficial microbes on various biological, chemical, and physical properties of soil and its productivity. Three replicates of the experimental treatments were set up in a split-plot design, in which there were four main plots: conventional soil tillage (ST) treatment for all three seasons (ST1); tillage in the first and second seasons (ST2); tillage only in the first season (ST3); and no tillage for all three seasons (ST4). However, the subplots (soil additives) were conditioned as follows: without treatment (control, T1); compost (C, T2); beneficial microorganisms (BM, T3); and combination (C + BM, T4). The biological property results showed that ST4T4 treatment produced high levels of microbial communities (bacteria, fungi, and actinomycetes), as well as high levels of soil enzyme activity (dehydrogenase, urease, and phosphatase), during the three growing seasons. However, the second season produced high numbers and dry weights of cowpea plants’ nodules. Additionally, changes in the chemical and physical properties showed that the application of various soil tillage treatments during the examined seasons led to significant increases in electrical conductivity (ECe, dSm−1), bulk density (BD, kg m−3), and soil infiltration rate (IR, cm h−1), following the trend of ST4 &gt; ST3 &gt; ST2 &gt; ST1. In contrast, the results revealed decreases in the exchangeable sodium percentage (ESP, %), porosity (PO, %), soil aggregates (stable aggregates and optimal-sized aggregates, %), and soil penetration resistance (SPRa, Mpa). The combination treatment (ST4T4) provided the best yields, with grain yields of 4.991 and 5.325 tons ha−1 and straw yields of 5.214 and 5.338 tons ha−1 in the first and third seasons (wheat), respectively. Cowpea plants showed the same pattern in the second season. Therefore, improvements in soil properties and enhancements in biological activity help maintain its productivity and fertility through simplified tillage processes that reduce interference with the soil surface layer.

Changes in Molecular Structure of Humic Substances in Cambisols under Agricultural Use

Soil organic matter stability and transformation affected by agriculture is a global problem of great concern. This study aimed to reveal structural changes in humic molecules under conventional soil tillage in Cambisols of the Transbaikal area. Humic acids were isolated from the humus horizons of native and arable variants of Eutric Cambisol Cryic (gleyic, humic, loamic) from the forest steppe, and Haplic Cambisol (arenic, humic, protocalcic) from the steppe zone. The changes in the humic substances’ quality were evaluated by means of an elemental analysis and 13C nuclear magnetic resonance spectroscopy. The results indicate that different agronomic management affected the changes in the composition and molecular structure of humic acids. Soil tillage induced an increase in the carbon content, the proportion of aromatic compounds and carboxyl groups and the depletion in nitrogen. As measured by 13C NMR spectroscopy, the intensity of these changes was determined by soil properties and the hydrothermal regime. Organic matter from Eutric Cambisol Cryic was suggested as providing significant environmental resistance to the agricultural impact due to the optimization of the water regime and a loamy texture. Prolonged ploughing of sandy Haplic Cambisol under the arid conditions promoted deep changes in the humic substances’ composition and chemical structure.

The Assessment of Soil Quality in Contrasting Land-Use and Tillage Systems on Farm Fields with Stagnic Luvisol Soil in Estonia

Soil quality indicates the soil’s ability to provide ecosystem services. Reducing the tillage intensity has been suggested as an alternative to conventional tillage for sustaining soil quality. This study aimed to evaluate the effect of soil tillage systems on individual soil quality indicators in comparison to those on grassland with Stagnic Luvisol soil in Estonia. Four soil management systems were compared: no-tillage (NT), minimum tillage (MT), conventional tillage (CT) and grassland (G) as a reference. Soil quality indicators included physical (bulk density, water-stable aggregates, porosity, air-filled pores, moisture content, water-holding capacity, penetration resistance and water permeability), chemical (total N, total soil organic C, permanganate oxidisable C, pH, P, K, Ca and Mg) and biological (earthworm abundance) parameters. CT soils had a significantly lower aggregate stability compared to MT and G soils. The higher penetration resistance of CT under an arable layer suggested the presence of a plough pan. NT improved the soil’s physical quality at 5–10 cm, which was indicated by higher moisture content, water-holding capacity and porosity and a lower bulk density, whereas penetration resistance exceeded 2 MPa in the lower part of the topsoil. NT also had significantly lower total soil organic C and total N compared to MT and G. The absence of tillage in the NT and G systems may have improved the soil’s resistance to moisture loss under dry conditions, which, in turn, improved the soil habitability for earthworms a despite higher density. In general, NT or MT stabilised or increased the soil quality compared to CT.

Responses of N2O emissions to straw addition under different tillage soils: A 15N labelling study

Nitrous oxide (N2O) emissions contribute to global climate change and are regulated by the intensities of N mineralization, nitrification and denitrification processes. These processes depend on soil management, e.g., tillage and straw addition. Microbial mechanisms underlying the effects of straw addition on N2O emissions were investigated by 56-day incubation of soil from a long-term (27-year) no-tillage (NoTill) and conventional tillage (ConvTill) field experiment. The abundance of N functional genes (amoA, amoB, nirK, nirS and nosZ) in no-tillage and conventional tillage soils was analysed based on straw addition. The application of 15N-labelled straw allowed us to trace N2O sources. Conventional tillage with 15N-labelled straw (ConvTill+Straw) reduced N2O emissions derived from soil by 42 %, whereas no-tillage with 15N-labelled straw (NoTill+Straw) reduced N2O emissions by only 8 % compared with soil without straw addition. The N2O emissions derived from straw were higher under NoTill+Straw than under ConvTill+Straw, whereas they accounted for only ~4 % of the total N2O emissions under both conditions. The nirK and nirS gene abundances were higher than those in soil without straw addition. Compared to that under ConvTill, the nosZ gene abundance was higher and the N2O emissions were 40 % lower under ConvTill+Straw, indicating its strong capacity to reduce N2O to N2. Pathway analysis showed that gene (amoA and nirK) abundance combined with soil properties (particulate organic matter nitrogen (POMN) and NO3−) were the main factors affecting N2O emissions, with increased POMN and nirK abundance driving increased N2O production under NoTill+Straw. However, gene (amoA, amoB, nirS and nosZ) abundances affected N2O emissions, with the nosZ gene being the main factor decreasing N2O under ConvTill+Straw. These findings revealed that straw return suppressed N2O emissions in conventional tillage soil, which may mitigate greenhouse gas emissions.

Soil structure under tillage systems with and without cultivation in the off-season

Conservation systems, such as no-tillage, follow as principles the absence of soil tillage, formation and maintenance of vegetation cover, and crop rotation. Nevertheless, when one principle is not adequately adopted there may be alterations in soil aggregation and porosity. Thus, this study aimed to evaluate physical attributes and organic carbon of the soil in an area with tillage and fallow in the off-season and in areas without soil tillage, with fallow and with crop in the off-season. The soil of the three areas was characterized as an Oxisol with clayey texture. For more than 10 years, corn has been the main crop grown in the season period in the three areas: conventional soil tillage system with fallow in the off-season (CTS), no-tillage system with fallow in the off-season (NTS-f), and no-tillage system with grass-grass succession (NTS-g). Each area was sampled at 20 random points and soil samples were collected from the layers, 0–0.1 m, 0.1–0.2 m and 0.2–0.3 m. The data were subjected to multivariate factor analysis, where two factors were identified, called “soil aggregation” and “soil porosity”. Through the “soil aggregation” process, it was found that clay is essential for the formation of aggregates with diameter of up to 2.0 mm, while soil organic carbon influences the formation of macroaggregates. The “soil aggregation” was higher in the area under NTS-g, and lower in the areas under NTS-f and CTS. The practice of fallow in the off-season in a no-tillage system proved to be harmful to soil structuring, especially in relation to soil aggregation. In the area under CTS there was greater "soil porosity" in the 0–0.1 m layer, but this effect is temporary, due to the large amount of microaggregates generated in this system, which over time obstructs soil pores and causes lower porosity than that determined under the no-tillage system.

Soil tillage and agricultural crops affect greenhouse gas emissions from Cambic Calcisol in a temperate climate

ABSTRACT Conventional soil tillage creates suitable conditions for plant growth, but it is an energy and labor-intensive technology causing ecologically unfavorable changes in the soil. In order to reduce GHG emissions from agricultural soils, reduced soil tillage and different crops have been proposed. However, the impact of individual practices on GHG emissions is affected by multiple on-site variables and is limited to different soil types and climate zones. Therefore, the aim of this study is to investigate the impact of two soil tillage treatments and four agricultural crops on GHG emissions from clay soil in temperate climate. During the growing seasons from 2018 to 2021, we measured soil flux of N2O, CH4 and CO2 using a Picarro G2508 on a broad multifaceted field experiment with two tillage treatments. This study shows that winter wheat with conventional tillage treatment may emit significantly lower N2O emission (8.3 g ha−1 day−1) and higher CH4 assimilation (−11.9 g ha−1 day−1) in warmer and drier growing season compared to winter wheat (26.1 g ha−1 day−1 and −3.3 CH4 g ha−1 day−1, respectively) and spring barley (11.1 g ha−1 day−1 and −2.9 g ha−1 day−1, respectively) with reduced tillage treatment in cooler and wetter growing season (p<0.05).

Cover crops maintain or improve agronomic performances of maize monoculture during the transition period from conventional to no-tillage

Maize monoculture systems often cause environmental impacts such as soil erosion, nitrate leaching and pesticide transfer. Conservation tillage and the use of cover crops appear to hold promise for limiting these impacts, but questions about their performance remain, particularly during the transition period after conventional soil tillage ceases. In this study, effects of no-tillage maize and fallow-period management with different cover crop species, either pure or in mixtures, were studied on the agronomic performance of maize and on soil N and water dynamics. The study combined field experiments over three years (2012–2014) and simulation modelling with the STICS model. The biomass of cover crops produced during the fallow period varied from 0.8 to 10.5 t dry matter ha−1 depending on the cover crop species and date of termination. Differences in soil water content were quantified among the treatments studied, with the lowest water content at the beginning of the maize growing season with late termination of a cover crop composed of pure faba bean or a vetch-oat mixture in 2014 (25–50% of plant-water available capacity). Maize grain yields ranged from 8.5 to 13.6 t dry matter ha−1, with the lowest yields in the bare soil treatment. Simulations with STICS were consistent with the observations and indicated a decrease in drainage of 8–38 mm year−1, depending on the year and cover crop. Introducing cover crops into maize systems is a powerful mechanism for maintaining production while improving environmental performances during the transition phase of soil properties in conservation tillage.

The use of the No-till technology in autumn wheat cultivation in order to increase the capacity of soil water accumulation and the decrease of fuel costs

Traditional agricultural practices, based on intensive soil tillage, have not ensured the sustainable development of agriculture. At the same time, innovative technologies used in agriculture are becoming less efficient or have a short-term effect, causing negative consequences for the environment. In addition, prices for non-renewable energy sources and their derivatives are increasing, which directly affects the stability of the agricultural sector. In this context, a new paradigm of agricultural intensification is needed, based on the conservation of natural resources, the reduction of production costs and the prevention of environmental degradation. The Conservation Agriculture System (CAS) is able to answer these questions by implementing them correctly, respecting all its basic principles: crop rotation, minimal soil disturbance and ensuring an optimal layer of mulch on soil surface. In our experiment the extra yield from conventional soil tillage was equal to the economy of fuel by using No-till technology, without taking in consideration other advantages for No-till.

Deep tilling and localized liming improve soil chemical fertility and sugarcane yield in clayey soils

The selection of an appropriate soil tillage system for improving yields and longevity is an important decision in sugarcane cultivation. In the present study, the effects of different soil tillage systems and methods of applying lime on sugarcane stalk and sugar yield performance as well as soil fertility parameters were evaluated throughout the sugarcane crop cycle. The experiments were established in two locations in April 2015 and conducted until August 2019, corresponding to a total of 4 growing seasons. A field study with a randomized block design was established with four replicates considering 4 treatments: conventional soil tillage system (CT), deep strip-tillage system (DT) and modified deep strip-tillage system (MDT), all with the same lime rate; and a standard treatment (control, CT without liming). Immediately after harvesting plant cane (18 months (mo) after planting), first ratoon (30 mo after planting), second ratoon (42 mo after planting) and third ratoon (54 mo after planting), soil samples were collected from a depth of 0.0–1.00 m, stratified every 0.2 m. Leaf material was sampled during the period of full vegetative growth. Analyses of soil chemical fertility, leaf concentrations of elements, and sugarcane yield components were performed. MDT was found to correct soil acidity most efficiently, mainly due to the positioning of the lime application. Under high aluminum saturation (AS), especially in deeper layers, deep lime placement was more effective and resulted in the best distributions of calcium (Ca2+) and magnesium (Mg2+), the highest base saturation (BS) and the lowest AS compared with the other treatments. Lime application was more important than the tillage system for improving the sucrose concertation and total recoverable sugar (TRS), whereas the tillage system affected the stalk yield and, consequently, the yield of sugar. Compared with DT and CT, the average stalk yield was 4.1% and 9.4% higher, respectively, under MDT at Macatuba and 6.3% and 15.3%, higher, respectively, under MDT at Piraju. Similarly, MDT improved average sugar yield by 3.7% and 10.4% at Macatuba and 6.1% and 16.3% at Piraju. Overall, long-term assessments, which are important for semi-perennial crops like sugarcane, showed that the both deep strip-tillage were most effective.

Trifluralin and Corn Residues for Weed Management in Mung Bean Fields, Central Iraq

A field experiment was conducted at two sites (Baghdad and Wasit Governorates) to evaluate the effects of allelopathic corn residues applied as soil incorporation or mulch, alone and in combination with reduced (50% of recommended dose) rate of trifluralin herbicide on weeds growth and mung bean yield. Conventional soil tillage and zero soil tillage treatments with corn residues were performed, while 50% dose and full dose of trifluralin only (without residues) treatments were included for comparison. Soil incorporation and mulch of corn residues reduced weed density and dry weight biomass and improved yield and yield components of mung bean in both sites. Mulch application was more effective than soil incorporation for weed control. However, the reduction in weed growth and the increase in mung bean yield were below the levels achieved by the label dose of herbicide. Application of 50% dose of trifluralin in plots incorporated or mulched with corn residues reduced weeds and scored yield similar to that achieved by 100% herbicide dose applied in both conventional and zero tillage plots. Chemical analysis revealed the presence of higher phenolics in plots amended with incorporated and mulched corn residues compared to their control plots. Chemical analysis also revealed that the periods of maximum quantities of phenolics paralleled with the periods of maximum suppressive activity against weed tested under field condition, which explains the phytotoxicity of phenolics on weed suppression. Such approach may help in reducing reliance upon high concentrations of trifluralin herbicide, improving the sustainability of agroecosystem, improving environmental safety, mitigating human health risks, and reducing the ability to tolerate herbicides.

Greenhouse gas emissions from the wheat-maize cropping system under different tillage and crop residue management practices in the North China Plain

With increasing attention being placed on mitigating global warming and achieving agricultural sustainable intensification, conservation agriculture practices have gradually been implemented in the North China Plain (NCP). However, there are still knowledge gaps on the effects of conservation practices on greenhouse gas (GHG) emissions in this area. In this study, a four-year field experiment was conducted from 2014 to 2018 to assess the effects of tillage and crop residue management practices on the emissions of nitrous oxide (N2O) and methane (CH4). Subsequently, crop yields, area-scaled and yield-scaled total non-carbon dioxide (CO2) GHG emissions were assessed. Our research found that no-till (NT) decreased N2O emissions by 22.6% compared with conventional tillage (CT) in winter wheat (Triticum aestivum L.) seasons, but there was no difference between tillage practices in summer maize (Zea mays L.) seasons. Crop residue retention practice (+R) increased N2O emissions by 28.1% and 26.7% compared with residue removal practice (−R) in winter wheat and summer maize seasons, respectively. The NT soils took up more CH4 compared with the CT soils in summer maize seasons. Area-scaled total non-CO2 GHG emissions showed trends similar to those of N2O emission. Since crop residue retention improved the maize yield compared with the residue removal treatments, yield-scaled total non-CO2 GHGs emission did not differ between residue management practices in summer maize seasons. Our four-year field measurements indicated that no-till practice could be more useful as an option to mitigate non-CO2 GHG emissions in the wheat – maize cropping system.

Exchangeable potassium reserve in a Brazilian savanna Oxisol after nine years under different cotton production systems

Adequate potassium (K) fertilization is essential for agricultural production in soils of the Brazilian Savanna (Cerrado biome) due to the high demand by crops (especially cotton), likelihood of leaching losses, and the dependence on fertilizer importations. Therefore, sustainability requires improvements in the soil efficiency management. This study evaluated the influence of soil management and crop succession or rotation combinations with cotton on K dynamics and exchangeable reserves in the soil profile, and the partial balance of K after nine years of cultivation in a clayey Oxisol in the Cerrado. The soil was sampled in layers up to 100 cm depth in four cotton production systems treatments: 1) conventional soil tillage (CST) with cotton monoculture; 2) CST with annual cotton-soybean-cotton succession; 3) CST with cotton/soybean/maize rotation; and 4) no-tillage system (NTS) with cotton/soybean/maize rotation and Urochloa ruziziensis (ruzigrass) as a cover crop in the off-season after grain crops. The experiment was conducted using a randomized block design with four replications. CST with cotton monoculture favored the leaching of K surplus from fertilization. Crop rotation including ruzigrass in the NTS allowed better control of K dynamics, ensuring its circulation in the soil-plant compartments and reducing leaching. The increased organic matter (OM) in this system enlarges the storage capacity of K in the topsoil. The adoption of no-tillage crop systems integrating ruzigrass is viable to improve the efficiency of K fertilizers in cotton cultivation in highly weathered tropical soils.

No-tillage promotes C accumulation in soil and a slight increase in yield stability and profitability of rice in subtropical lowland ecosystems

Context The effects of no-tillage (NT) on soil organic C (SOC) and rice yield in lowland soils are poorly understood in subtropical ecosystems. Aims In a long-term (24 years) field experiment, we assessed the effect of NT on SOC stocks in labile (&gt;53 μm, particulate) and stable (&lt;53 μm, mineral associated) fractions of soil organic matter (SOM), grain yield, between-season stability, and gross margin compared to conventional tillage (CT) and pre-germinated tillage (PG) systems in a lowland Gleysol in southern Brazil. Methods Soil from eight different layers down to 40 cm under each tillage system was sampled in a field experiment, and additional soil samples were obtained from an adjacent area under native grassland (NG) as reference for SOC stocks. Key results While the PG and CT systems maintained similar SOC stocks as the NG soil, NT increased SOC stocks at an annual rate of 0.41 Mg ha−1 in relation to the traditional CT soil. Rice grain yield increased twice over the 24-year period, amounting to 12 Mg ha−1 in the last crop season. Despite lower yield in NT system in most crop seasons, a slight effect on yield stability and profitability (&lt;10%) in favour of NT, compared with CT and PG systems, was observed. Conclusions Based on our findings, NT promotes C accumulation in subtropical paddy rice soils. Implications There is a beneficial effect of NT on rice yield stability and profitability in the long term.

Soil carbon sequestration and soil quality change between no-tillage and conventional tillage soil management after 3 and 11 years of organic farming

ABSTRACT The aim of this study was to evaluate the long-term effect of no-tillage systems in organic farming on soil carbon sequestration and soil quality, which is associated with nutrient availability. The experiment was conducted on a low-input organic farm since 2009, using a randomized complete block design with four replications. Two treatments, conventional tillage (CT) and no-tillage (NT), were tested. Soil samples were obtained after crops were harvested in 2012 and 2020 from four different soil depth layers between 0‒30 cm, and the physical and chemical properties of soil samples were measured. Data were analyzed using ANOVA with Tukey tests (α = 0.05), while the correlation was analyzed based on Pearson correlation. At 0–2.5 cm and 2.5–7.5 cm depths, soil bulk density (BD) in the NT treatment was 30% and 8% lower, respectively, in 2012, and 25% and 14% lower, respectively, in 2020 compared with the CT treatment. The NT treatment could enhance the soil organic carbon (SOC) better than CT treatment at the same depth, sequestering a greater amount of carbon in the soil. Compared with the CT treatment, SOC concentration in the NT treatment was 76% and 12% higher, respectively, in 2012, and 103% and 38% higher, respectively, in 2020. In 2012, the SOC stock showed a significant difference between NT and CT treatments only at the 0–2.5 cm soil depth, with the value being 24% higher in the NT treatment than in the CT treatment. However, in 2020, the SOC stock was 50% and 19% higher in the NT treatment than in the CT treatment at 0–2.5 cm and 2.5–7.5 cm depths, respectively. The SOC also could significantly expand cation exchange capacity (CEC) and the availability of some nutrients in the soil. However, the relationship between was weak in 2020. Moreover, the NT treatment showed better progression of humification than CT. Finally, long-term NT systems in low-input organic farming could reduce soil bulk density and enhance soil carbon sequestration and soil quality. However, this system must be complemented with the conventional approach to maintain nutrient balance for long-term management.

APPLICATION OF FRACTAL THEORY IN QUANTIFYING SOIL AGGREGATE STABILITY AS INFLUENCED BY VARYING TILLAGE PRACTICES AND COVER CROPS IN NORTHERN GUINEA SAVANNA, NIGERIA

&lt;p&gt;&lt;strong&gt;Background.&lt;/strong&gt; Soil aggregate stability varies with management practices like tillage and soil organic matter management. &lt;strong&gt;Objective.&lt;/strong&gt; The objectives of this study were to (i) Explore a fractal theory to investigate the extent of soil fragmentation in soil of Samaru, Northern Nigeria, subjected to different tillage practices and covers crops for the purpose of improving soil aggregate stability (ii) Establish a relationship between fractal dimension (D) and mean weight diameter (MWD). &lt;strong&gt;Methodology.&lt;/strong&gt; A three years field trials was conducted with three tillage practices (no-till, reduced till and conventional till) as main treatments and four cover crops (&lt;em&gt;Centrosema pascuorum, Macrotyloma uniflorum, Cucurbita maxima&lt;/em&gt; and &lt;em&gt;Glyine max&lt;/em&gt;), and a bare/control (no cover crop) as sub treatments. The trial was laid out in randomized complete block design, split plot arrangement and replicated three times. Soil samples were collected at 0-15 cm prior to trial establishment for routine soil physical and chemical properties and at depths 0-5, 5-10, 10-15 and 15-20 cm at the end of each cropping season each year for soil aggregate stability test. &lt;strong&gt;Results. &lt;/strong&gt;No-till soils had 12.58% better soil aggregate stability than soils under reduced and conventional tillage systems. Also, no-till soils had 2.40 % less fragmented soil aggregates than Reduced and Conventional till soil as indicated by the fractal dimension of soil aggregates. Soils under &lt;em&gt;Macrotyloma uniflorum&lt;/em&gt; cover crop, were on the average 2.33% less fragmented than soils under &lt;em&gt;Centrosema pascuorum, Glycine max &lt;/em&gt;and&lt;em&gt; Cucurbita maxima&lt;/em&gt; but 4.56% less fragmented than soils with no cover crops. &lt;strong&gt;Implication, &lt;/strong&gt;No-till and reduced till systems; and cover cropping better enhanced soil aggregate stability due to better accumulation of organic matter emanating from crop residues return to soil in these practices. &lt;strong&gt;Conclusion.&lt;/strong&gt; Conservation tillage and the use of cover crops lowered soil aggregate fragmentation relative to conventionally tilled system and bare soil with no cover crop. The strong linear relationship established between MWD and fractal dimension showed over 80% dependency, suggesting that fractal dimension is another useful index for evaluating soil aggregate stability.&lt;/p&gt;&lt;p&gt;.&lt;/p&gt;