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This study quantified the immediate impact of soil deformation caused by agricultural vehicle traffic on the anisotropy of the topsoil pore system and gas transport properties (air permeability, gas diffusivity). A field experiment was conducted with five repeated passes of a two-axle self-propelled agricultural vehicle (wheel load 8 Mg, tyre size: 1050/50 R32, tyre inflation pressure: 100 kPa) on an arable clay soil (crop at the time of the experiment: grass ley) in north-western Switzerland. Undisturbed cylindrical soil cores were collected in non-wheeled areas, at the edge of the wheel rut (i.e., at 0.5 m lateral distance from the centre of the wheel track), and at the centre line of the wheel track. The soil cores (0.1 m diameter, 0.06 m in height) were taken in two directions (vertical and horizontal) in the topsoil (0.1 m depth). Air-filled porosity (ε a), air permeability (k a) and relative gas diffusivity (D p / D 0) were measured at three matric potentials (corresponding to p F 1.5, 2.0, and 2.5, respectively). The vehicle-induced deformation resulted in significantly reduced ε a , k a , D p / D 0 in the topsoil. Air permeability was highly anisotropic in non-wheeled soil, with higher k a in vertical direction. Compaction mainly affected macropores and hence k a at the wet end (p F 1.5), decreased the vertical k a more than the horizontal k a , and consequently, k a became less anisotropic due to compaction. This effect was stronger under the edge of the wheel rut than in the centre of the wheel rut. The anisotropy of D p / D 0 was little affected by the vehicle-induced soil deformation. Our results show that soil deformation due to vehicle traffic not only decreases the gas transport capacity of soil but also changes the anisotropy of air permeability, with consequences on soil aeration and soil-atmosphere gas exchange. • Impacts of wheeling are different under the centre and under the edge of the wheel rut. • Wheeling decreased the gas transport properties and changed the anisotropy. • Air permeability was more affected than gas diffusivity. [ABSTRACT FROM AUTHOR]

Here, we investigated the effects of biogas digestate application on flow pathways and soil properties in a sandy soil aiming at unraveling phosphorus accumulation and depletion processes in fertilized soils. Dye tracer experiments were conducted to visualize and distinguish between various flow pathways, while X-ray tomography was utilized to characterize the soil structure. The dye tracer experiments revealed differences between the control and the digestate-treated group of soil profiles in the top-soils although no statistical verification was possible amid a single plot per treatment. The stained soil profiles in both treatments indicate extensive areas of homogeneous and heterogeneous matrix flow. However, the digestate-treated group showed a decrease in homogeneous matrix flow and a notable presence of preferential flow with low interaction. The application of biogas digestate impacted various soil properties, including organic carbon content, water drop penetration time, and pH levels. Accordingly, the topsoil experienced an increase in soil organic carbon, water repellency, and a decrease in pH levels. The fraction of macropores also increased in the topsoil of the digestate-treated group, accompanied by an increase in tortuosity. Double lactate-extractable phosphorus (DL-P) distribution varied across the different flow pathways, with higher concentrations detected in matrix flow and a depletion observed in preferential flow regions in both treatments. These findings confirm the close relationship between the type of flow pathway and phosphorus distribution in soils. Additionally, a significant correlation was observed between pH levels and DL-P in the digestate-treated group, indicating potential implications for phosphorus availability. Overall, the results of this study suggest that the long-term application of biogas digestate is likely to improve soil properties as related to soil organic matter content, particularly in the topsoil of sandy soils. The study highlights the significance of the prevailing flow and transport pattern on nutrient distribution, with potential implications for nutrient management in agricultural systems. While the study design presented prevents the unequivocal assignment of differences to treatment effects, our data likely illustrate the impacts of biogas digestate amendment on the investigated sandy soil. Further research should focus on assessing the long-term effects of digestate application in loamy and clayey soils. • The impact of digestate on topsoil organic matter and water repellency is notable. • The application of biogas digestate tends to reduce the extent of homogenous matrix flow. • Macroporosity, air-filled porosity, and tortuosity alter with digestate application. • The spatial distribution of soil phosphorus exhibits high variability and is influenced by the flow field. [ABSTRACT FROM AUTHOR]

The application of spent coffee grounds (SCGs) to soil has been widely encouraged because of the agronomic benefits of SCGs. However, the negative impacts of this practice are not fully understood. This study aims to present the effect of nanosized SCGs (n SCGs) on the dispersibility/transportability of soil clay. An n SCG sample with an average hydrodynamic size of ∼260 nm was extracted from SCG waste, and its effects on the dispersibility of clay were tracked over a pH range of ∼3 to ∼9 and an ionic strength range of 0.001–0.1 N by using dynamic light scattering techniques and a test tube-based method. n SCGs were found to carry negative charges (zeta potential, ζ, varying from −2 to −30 mV), and the presence of n SCGs in clay suspensions resulted in decreases in the surface charge (towards more negative charge) of the clay suspensions, particularly at pH < 6. By providing more negative charges to the clay system, n SCGs stimulated and favoured clay dispersal. The edge surface of clays and Fe oxides may play a central role in promoting soil particles association, but this effect was likely weakened in the presence of n SCGs. In ge n eral, it can be inferred that the utilization of SCGs may have adverse impacts such as soil/clay losses or soil structural changes, and these impacts need to be considered. [Display omitted] • Nanosized spent coffee grounds (n SCGs) occur in soils due to soil application. • n SCGs were found to carry negative charges over the pH range of ∼3 to ∼9. • n SCGs added to clay suspensions make the surface charge of the system more negative. • n SCGs were found to promote the dispersal of clay. • The colloidal properties of n SCGs are strongly governed by pH and IS. [ABSTRACT FROM AUTHOR]

Soil compaction combined with water deficit may cause a significant decrease in microbial functions. Two texture-contrast sugarcane soils were exposed to the combined stresses of compaction and drought, and microbial responses were investigated going into stress (phase I) as well as their response coming out of stress (phase II). We artificially applied a gradient of bulk densities (0.9–1.5 g cm−3) and water-filled pore space (WFPS, 21–100%) to simulate compaction and drought conditions. PCA results clearly demonstrated the separation of impacts of soil types and the moisture treatments. Additionally, it is evidenced that soil texture can strongly regulate soil microbial response to compaction, as finer texture provides a better local environment for soil microbial community growth, supported by two folds higher microbial biomass carbon content and significantly higher CO 2 respiration in Nitisol (clayey soil) than Planosol (sandy soil). The Structural Equation Modelling (SEM) analysis showed a strongly direct negative effect (path coefficient= −0.59 to −0.61, p < 0.01) of WFPS on the labile C at Phase I and Phase II in both Nitisol than Planosol. Further, soil moisture would govern microbial respiration cross soil types, particularly after removal of compactions which supported by the SEM result (path coefficient= −0.36 to −0.47, p < 0.05). Results from this study have implied the importance in considering the combined effects of soil texture and moisture in assessing compaction impacts and developing associated management regimes. [Display omitted] • Microbial response to compaction varied with soil moisture levels and texture. • Water filled pore space regulates microbial activity at the low moisture level. • Clayey soil showed a greater microbial response to compaction and moisture level. • Clayey soil showed higher resistance to compaction in comparison to sandy soil. [ABSTRACT FROM AUTHOR]

Recent studies have shown that long-term irrigation with treated wastewater (TWW 1 1 Treated wastewater irrigation (TWW): Freshwater (FW): Blended TWW:FW in a 1:1 ratio (MIX): Low-frequency TWW-irrigation (LFI): TWW irrigated tuff trenches (TUF)) can lead to land degradation and reduction of crop performance in clayey soils due to additions of salts and organic compounds. This study investigated the effects of two remediation and two mitigation methods intended to alleviate the damage to soil properties following long-term irrigation with TWW. The experiment was conducted in a 'Hass' avocado orchard (Persea americana Mill.) grown on a clayey soil irrigated with TWW since 2009. The treatments implemented in 2016 included: TWW (control), freshwater (FW), blended TWW:FW in a 1:1 ratio (MIX), low-frequency TWW-irrigation (LFI), and TWW irrigated tuff trenches (TUF). The results showed that FW and MIX significantly reduced total salinity, salinity-related ions (Na and Cl), and sodium adsorption ratio (SAR) to (i) depths of 90 cm and 30 cm under drippers, respectively, and (ii) depths of 60 cm (except for chloride) and 30 cm between drippers, respectively, compared with TWW. TUF and LFI reduced soil salinity and sodicity under drippers but not between drippers compared with TWW. Moreover, FW significantly increased aggregate stability to a depth of 30 cm. TUF had the highest oxygen concentration in the root zone (35 cm depth), followed by FW. Considering the scarcity of freshwater, MIX and TUF are suggested as possible measures for reducing soil salinity and sodicity, and increasing aeration of clayey soils under long-term irrigation with TWW, respectively. Our findings contribute valuable insights into strategies for remediating and mitigating the detrimental effects of TWW irrigation on soil, thus promoting sustainable agriculture in regions facing water scarcity. • FW reduced EC, Na and SAR than TWW both under and between drippers to 60 cm depth. • FW reduced salinity and sodicity at 15 cm away from drip laterals to 30 cm depth. • MIX significantly reduced EC, Na and SAR than TWW to 30 cm depth under drippers. • TUF increased oxygen concentration to 35 cm depth than all treatments. • TUF effects on EC and SAR was restricted to the wetted area bellow the drippers. [ABSTRACT FROM AUTHOR]

To achieve sustainable agricultural activity, phosphatase determination is an important practice for improving the efficiency of phosphorus (P) management in tropical agriculture. The objective of this study was to evaluate acid phosphatase activity in different soil textures and P stress levels affecting the nutritional, chemical, biochemical, and agronomic aspects of soybean. Treatments resulted from factorial combination in a 3 × 3 factorial scheme, consisting of three soil textures (clay, medium, and sandy) and three P stress levels (severe, moderate, and control) with four replications. Three different soil textures were used in the research: Latossolo Vermelho Distrófico (LVd) with clay texture, collected in the native forest, equivalent Oxisol (Soil Taxonomy); Cambissolo Háplico Tb Distrófico (CXbd) with medium texture collected in the natural field equivalent Inceptisols (Soil Taxonomy); and Latossolo Amarelo Distrófico (LAd) with sandy texture collected in the natural field equivalent Oxisol (Soil Taxonomy). Soil electrical conductivity, P available (method Mehlich-1), and acid phosphatase activity (ρ-nitrophenol released) (μg h−1 g−1 soil) were analyzed and the samples were collected at a depth of 0–20 cm. Also evaluated were the height of plants, number of leave and branches, dry mass (root, leave, and stem), P total concentration in leaf, and P translocation (transport from root to shoot) of soybean plants 45 days after sowing. Results showed the clayey textured soil provided the best results for plant growth, root, stem, and leaf dry matter content, P total concentration of P in leaf, P translocation (transport from root to shoot), P available in the soil, and higher acid phosphatase activity of under P stress. Results showed that the Latossolo Vermelho Distrófico (LVd) provided the best results in managing P in different soil textures. However, based on growth and development results, a reduction in phosphate fertilization (P stress moderate) may favor acid phosphatase activity. Acid phosphatase activity can be used as an option in the management of P soluble activity in different soil textures. However, in front of the complexity of soil–plant–P–environment interactions, further research needs to be conducted to investigate better these effects of the da acid phosphatase on different soil textures. • Different soil textures affect acid phosphatase activity. • Phosphatase is an important practice to improve phosphorus efficiency. • Different soil textures affect root and dry matter production in soybean. • Moderate P stress may favor acid phosphatase activity. [ABSTRACT FROM AUTHOR]

Despite numerous individual studies evaluating the impact of straw return on soil organic carbon (SOC) stock in upland wheat and maize croplands in China using no-tillage (NTS), rotary tillage (RTS), and deep tillage (DTS) practices, the results have shown inconsistency. In addition, several factors influence the effects of various tillage practices with straw return on SOC stock that are not well understand. In this study, we conducted a meta-analysis of 764 comparisons to determine the combined impact of SOC stock in the topsoil (0–20 cm) and subsoil (20–40 cm) layers, while considering factors such as climate conditions, management practices, and initial soil properties. The results indicate that straw return with different tillage practices significantly improved SOC stock in both soil layers compared to straws removal. The increase in topsoil SOC stock was nearly identical for NTS (7.38 %) and DTS (7.17 %), compared to the RTS. However, the increase in subsoil SOC stock was significantly higher for DTS (28.8 %). According to subgroup analysis, NTS has been more effective in increasing topsoil SOC stock in regions with medium temperature (10–15 °C) and low precipitation (<400 mm), when used in a single cropping system. However, in regions with higher temperature (>15 °C) and precipitation (>800 mm), DTS is more effective in increasing SOC stock in both topsoil and subsoil layers in a double cropping system. Long-term (11–20 years) DTS resulted in a significant increase in SOC stock in the topsoil (19.2 %) and subsoil (18.5 %), while the increased effects of NTS on SOC stock were only in topsoil layer (17.1 %). The effects of straw return on SOC stock were also found to be associated with soil texture, with NTS having a greater impact on sandy to loam soils, and DTS having a greater impact on clay soils. Furthermore, a significant (P < 0.01) positive linear relationship was observed between annual carbon (C) input and SOC sequestration in the topsoil under NTS, as well as in both soil layers under DTS. These findings have important implications for enhancing SOC in Chinese upland wheat and maize cropland soils through optimizing straw return, given that more than 518 million tons of crop straw are produced annually. • Effect of straw return and different tillage practices on SOC stock was analyzed. • Topsoil SOC stock increased more in NTS than RTS in semi-arid regions. • DTS has greater effects on subsoil SOC stock than RTS and NTS. • C inputs contribute to SOC accumulation in topsoil and subsoil layers. [ABSTRACT FROM AUTHOR]

Liming with 'structure lime', comprising approximately 80–85% ground limestone and 15–20% slaked lime, has been promoted in subsidised environmental schemes in Sweden since 2010 to increase clay aggregate stability and mitigate particulate phosphorus losses to surface waters. To date, approximately 65,000 ha have been structure-limed. Apart from stabilising aggregates, liming may also improve other physical properties, such as soil strength. This study examined the effect of increasing application rate (0–16 t ha-1) of structure lime on soil strength, approximated by horizontal (draught requirement) and vertical (penetrometer resistance) measurements, in eight field soils (clay content 26–38%) to which structure lime had been applied two, three, four or six years previously. Draught requirement when cultivating with a multipurpose cultivator significantly decreased (by 11%) with the highest application rate of structure lime (16 t ha-1) compared with an unlimed control. This reduced the wheel power requirement by 7.1 kW and diesel consumption by 1.2–1.4 L ha-1, and lowered CO 2 emissions by 3–4 kg ha-1. To clarify the general effect of structure liming, the mean value of all limed treatments was compared with that of the unlimed control. This showed that structure liming in general significantly reduced the draught requirement (by 7%). However, penetrometer resistance measurements revealed no significant effects of structure liming and no relation between draught requirement and penetrometer resistance measurements. Overall, the results indicate that structure liming can reduce fuel consumption, due to easier soil tillage, and thus lower CO 2 emissions. • Cultivator draught requirement was measured in structure limed field trials. • A towing eye with sensors that can measure forces in three directions was used. • Structure liming reduced horizontal draught requirement by 7%. • Reductions corresponded to decreases of 1.2–1.4 L diesel ha-1 and 3–4 kg CO 2 ha-1. • Structure liming did not affect penetrometer resistance in this study. [ABSTRACT FROM AUTHOR]

Slow- and controlled-release (SCR) nitrogen (N) fertilizers improve crop production and N utilization efficiency. However, responses of biological soil characteristics to the long-term application of N fertilizer have received little attention. In this work, a five-year field experiment was performed to assess the influence of different N fertilizer treatments (no N fertilizer application [CK] and applications of polymer-sulfur coated urea [PSCU], conventional prilled urea [PU], and urea-formaldehyde [UF]) on soil microbial communities in yellow clayey paddy soils in southern China. The types of N fertilizers had a stronger impact on soil bacterial diversity and community structure than fungal diversity and community structure. The soil microbial communities of PU and UF treatments did not differ from those of CK regarding alpha diversity indices. However, the PSCU treatment significantly decreased the Shannon index by 2.16% for bacteria but had no significant effect on the Shannon index of fungi. This might be due to the application of PSCU significantly reducing the soil pH by 0.16 units compared to CK and leading to soil acidification. Co-occurrence network analysis determined the keystone species mainly belonging to Proteobacteria and Ascomycota. Notably, these keystone species played an important role in PSCU-treated soils. Soil Ca2+, Na+, and NH 4 + were the main determinants of microbial network stability. These results contribute to our understanding of how SCR-N fertilizers impact soil microorganisms. • The application of polymer-sulfur coated urea significantly reduced soil pH. • Nitrogen fertilizer types had more significant effects on soil bacterial diversity. • Nitrogen fertilizer types significantly affected soil bacterial community composition. • Soil nutrient availability played critical role in driving microbial community change. [ABSTRACT FROM AUTHOR]

Phosphorus (P) interacts with soil constituents in many ways, forming compounds of distinct stabilities in a number of chemical inorganic and organic forms. The identification of these P compounds in tropical agro-ecosystems is especially relevant to understanding potential P availability in these common P-fixing soils, providing information to improve P use efficiency. In this study, we investigated P partitioning and speciation in Brazilian Cerrado Oxisols under different management systems using a combination of sequential chemical P fractionation (SPF), P K-edge XANES and 31P NMR spectroscopy. Topsoil (0–10 cm) samples were obtained from soils under three management regimes, including native vegetation (Cerrado), no-tillage (NT), and conventional tillage (CT) agriculture. Four representative agricultural sites in the Brazilian Cerrado were selected: Ox-1 (Costa Rica-MS), Ox-2 (Sapezal-MT), Ox-3 (Cristalina-GO) and Ox-4 (Tasso Fragoso-MA). In all sites, the soils are classified as Typic Hapludox, varying in cultivation time, soil clay content and oxide types. Long-term cultivation in NT and CT led to large P accumulation in the soil. Chemical P fractionation indicated that labile P was the smallest pool at all sites. P K-edge XANES showed that P is mostly sorbed to the Fe and Al hydr(oxides), goethite, hematite and gibbsite. It also showed that phytate was the predominant organic P species, depleting in sequence from native vegetation to NT and CT management systems. 31P NMR showed that monoester P was present in all soils and management systems, whereas diester-P was found only in soils under native vegetation. The combined use of SPF, XANES and 31P NMR data was necessary to fully understand inorganic and organic P chemistry and reactivity in these tropical agricultural croplands. • Soil P fractionation (SPF) was useful to identify labile P. • Like SPF, P K-edge XANES detected the majority of P sorbed on Fe/Al oxyhydroxides. • 31P NMR identified recalcitrant monoester-P as the major form of organic P. • 31P NMR identified diester-P only in the soils under native vegetation. • SPF, XANES and NMR should be combined for a clearer image of P in tropical soils. [ABSTRACT FROM AUTHOR]

The shrinkage and swelling behaviors of clayey soils could lead to cracks and erosions inducing severe damages to agricultural lands and engineering projects. Thus, improving the understanding of shrink-swell characteristics is crucial to nonrigid soils. However, it remains difficult for in-situ monitoring of soil shrink-swell processes continuously and nondestructively. The objective of this study was to present a thermo-time domain reflectometry (thermo-TDR) technique for determination of soil shrinkage and swelling dynamics and hydro-thermal regimes in-situ during wet-dry cycles. A field experiment on two clayey soils (a paddy soil and an alluvial soil) was conducted to evaluate the performance of the thermo-TDR method for in-situ determination of soil volume changes and associated hydraulic and thermal properties during wet-dry cycles. The results showed that both soils experienced considerable shrinking and swelling processes with maximum vertical deformations of 2.4 and 1.8 cm for the paddy soil and alluvial soil, respectively, and with maximum horizontal deformations of 370 and 280 cm2 for the paddy soil and alluvial soil, respectively, during a 36-day period. The thermo-TDR method provided volume change values (shown as the bulk density) agreed well with independent core-sampling measurements with an average RMSE of 0.15 Mg m−3 and a R2 of 0.46. A better agreement was observed between thermo-TDR measured bulk densities and values from the ruler-image processing method with an average RMSE of 0.07 Mg m−3 and a R2 of 0.77. Besides, the thermo-TDR method gave consistent in-situ soil shrinkage curve and water retention surface measurements by combining with soil matric potential sensors. Unlike rigid soils, the paddy and alluvial soils showed complicated hydro-thermal regimes in response to the shrink-swell processes. We conclude that the thermo-TDR technique is a reliable tool for continuous in-situ determination of soil shrink-swell processes. Future studies should focus on development of comprehensive soil heat and water transport models accounting for both moisture content and volume changes. • A thermo-TDR technique determines soil shrink-swell behaviors accurately in- situ. • New approach produces in- situ shrinkage curves and water retention surfaces. • Shrinkage and swelling have significant effects on soil hydro-thermal regimes. • Paddy soil is susceptible to the shrink-swell behavior than alluvial soil. [ABSTRACT FROM AUTHOR]

Tillage and nitrogen (N) fertilization have been shown to affect soil abiotic and biotic properties, but it is unclear how these impact long-term tillage systems in subtropical climates. We studied a 48-y wheat cropping trial in semi-arid, subtropical Australia that applied different tillage practices (no-till [NT] and conventional till [CT]) and N fertilization rates (0 and 90 kg N ha-1, 0 N and 90 N, respectively) in a Vertisol from 0 to 10 cm soil depth. Total organic carbon (TOC) significantly increased only when N fertilizer was applied under NT. Total nitrogen (TN) concentrations increased when N fertilizer was applied but were unaffected by tillage. N-acetyl-β- D -glucosaminidase (NAG) activity was highest when N was applied and α-glucosidase (α-Glu) activity was lowest in the NT and 0 N treatments. Activities of β-glucosidase, phenol oxidase and phosphatase were unaffected by the management practices. While the bacterial community composition appeared most distinct in NT and 0 N conditions, fungal community composition, and bacterial and fungal alpha diversity remained unaffected by the treatments. Although wheat yield was only significantly influenced by N fertilization rates, both NT and N fertilization may be preferable for management as these soils had the most favorable TOC, TN, and enzymatic activity. These differences seen between treatments here are less pronounced than reported elsewhere, with this likely a result of the high clay content of the soil which can have a buffering capacity, or that these treatments have less of an impact over longer time scales. Nevertheless, we conclude that no-tillage and N fertilization remain important in influencing soil properties and functioning over decades in this Vertisol in a semi-arid subtropical region. • Total organic carbon significantly increased when N was applied under no-till (NT). • Total N increased when N fertilizer was applied but there was no effect of tillage. • N-acetyl-β- D -glucosaminidase activity was highest when N was added. • Bacterial community composition was most distinct in NT and no N addition treatment. • Fungal community composition and bacterial alpha diversity were not affected. [ABSTRACT FROM AUTHOR]

The expansion of irrigation infrastructure in Tasmania, Australia, has led to intensified irrigated crop production, including for vegetables. This has resulted in increased irrigation of texture contrast soils, and other soils with high clay content in the subsoil. Widely used for rain-fed grain production in other parts of Australia, these soils have been subject to a range of soil amelioration approaches in an effort to improve their soil physical characteristics and capacity to produce crops. Subsoil manuring – the process of placing organic soil ameliorants at a target depth using a specially modified deep ripper – has proven to be successful in increasing yields of rain-fed grain crops. Locally available organic materials (chicken manure and poppy seed meal) were placed in the upper zone of a clay subsoil at three sites used for irrigated vegetable production. The crops grown were green peas for processing and carrots for seed production. Normal grower management practices were the reference against which treatments were compared. Subsequent measurements showed no consistent or significant benefit from subsoil manuring one year after treatment under the soil and crop management conditions used in this research. • Subsoil manuring has shown productivity benefits in rain-fed grain production. • Irrigated vegetables were grown on treated texture contrast and high clay soils. • No significant differences were found as a result of subsoil manuring treatments. [ABSTRACT FROM AUTHOR]

Adhesion between metal surfaces and soil can have significant effects on soil-tool interaction. The cone pull-out test (CPT) and piston pull-out test (PPT) for adhesion assessment were used in this study on smectite, illite and kaolinite clays at different water contents. In the CPT, the tangential adhesion stress (TAS) and cone adhesion (CA) were measured. In the PPT, the normal adhesion stress (NAS) and piston adhesion (PA) were measured. The results showed that the NAS and TAS depended on the type of clay. The ratios of NAS to TAS for smectite and kaolinite had the largest and smallest values, respectively. For all three types, NAS and TAS decreased as the water content (W) decreased. An increase in the thickness of the water film at the soil-metal contact surface reduced the stress required to separate the metal from the soil. The relationship between CA-W and PA-W for the three clay types differed. For smectite, a change in water content had no effect on CA or PA. For illite, an increase in water content decreased the CA and PA. For kaolinite, a bell-shaped curve formed such that, as water content increased, where WLL, CA and PA decreased. For all three clay soil types, NAS and PA were higher than TAS and CA at a specific water content. This demonstrated the effect of the metal-to-soil contact geometry on the adhesion parameters. The NAS and TAS values were classified in terms of clogging potential. Clogging potential is the adhesion of soil to the cutting tools or conveying system. The selection of the use of the CPT or PPT for adhesion assessment depended on the phenomenon being studied. • The metal-to-soil contact geometry does affect on adhesion parameters. • The normal adhesion stress (NAS) was higher than the tangent adhesion stress (NAS). • The piston adhesion (PA) was higher than the cone adhesion (CA). • The NAS and TAS decreased as the water content decreased. • There is linear relationship between NAS and TAS. [ABSTRACT FROM AUTHOR]

Organic wastes, fertilizers, organominerals, and minerals contain nutrients essential to crops and contribute to increase productivity. However their use can also lead to the accumulation of copper and zinc, which changes the distribution of their fractions and enhances the risk of toxicity to plants and the environment, thereby working against the sustainable development goals. However, the effect of manure applications on clayey soils and the effects of increasing Cu and Zn contents over the years on crop productivity remain unknown. This study aimed to evaluate the distribution and the potential for contamination of heavy metals in clayey soil with a history of the application of different types and amounts of fertilizers under Cynodon spp. grazing and no-tillage system for soybeans. In Experiment 1, Cynodon spp. were cultivated for hay production and submitted to applications of the following treatments: 0, 200, and 400 kg ha−1 of total-N in the form of pig slurry and urea. In experiment 2, the soybean was grown and subjected to the following treatments: control, pig slurry, commercial granulated solid organic fertilizer, organomineral fertilizer blended with granules, and mineral fertilizer blended with granules. The dose of each nutrient source was determined based on the soil analysis and the recommendations of the liming and fertilization manual. The experiments were conducted for four agricultural crops where soil samples were collected in the layer of 0.00–0.10 m layer and submitted to chemical fractionation of Cu and Zn. The use of pig manure increased the availability of Cu and Zn in the soil, causing an increase in the distribution of copper organic (40.73% and 57.64% for PS200 and PS400 treatments, respectively, in Experiment 1; 67.33% for PS treatment, in Experiment 2) and residual fractions (10.01% and 7.60% for PS200 and PS400 treatments, respectively, in Experiment 1; 9.80% for PS treatment, in Experiment 2), while zinc was predominant in clay-mineral (61.04% and 92.01% for PS200 and PS400 treatments, respectively, in experiment 1; 278.90% for PS treatment, in Experiment 2) and residual fractions (2.36% for PS200 treatment in experiment 1; 9.90% for PS treatment, in Experiment 2). Additionally, the use of swine manure increased the Cu and Zn contents in the exchangeable fraction, which may potentiate the toxicity to plants and increase the potential for contamination of subsoil water. However, the increased bioavailability of Cu and Zn did not caused a loss of crop productivity but instead increased dry mass production and crop yield. • Use of PS in the highest dose increases Cu and Zn available contents in the soil. • Use of PS accumulates Cu in the organic and residual fractions. • Use of PS accumulates Zn in the mineral and residual fractions. • There was no harm to Tifton 85 DM the accumulative production over the years. • There was no harm to soybean DM accumulative production and productivity over the years. [ABSTRACT FROM AUTHOR]

Cement and other traditional materials are frequently used to improve the properties of soil in the Yellow River Basin, the ecological environment has become severely polluted. To promote the environmental protection strategy of sustainable development, environmentally friendly biopolymers were used to treat typical silt samples collected from the Yellow River Basin. The water retention characteristics and vegetation growth of the treated silt were evaluated, and the microscopic mechanism of the water retention characteristics was investigated. The results show that the water retention capacity of the treated silt increased upon increasing the ratio of xanthan gum, gellan gum, and guar gum, with gellan gum performing better than the other two gums. The biopolymers had no discernible effect on the vegetation germination, but effectively promoted vegetation growth with a significantly lower wilting rate than that of the untreated soil. The soil treated with xanthan gum had the highest germination rate and vegetation growth height, while soil treated with gellan gum had the lowest wilting rate. The superior performance of gellan gum and xanthan gum can be attributed to their hydrophilicity and adhesion. These gums directly interact with the surface of charged clay particles in the soil pore space to closely connect the particles, reduce water loss, and increase the water retention capacity. The better soil water retention capacity is associated with improved germination and vegetation growth. • Water retention characteristics of biomolymer-treated soil in wide suction range. • Different biopolymers' effects on vegetation growth in treated soil. • The water retention capacity of treated silt increases as the ratio increases. • The water retention capacity of gellan gum was better than xanthan gum and guar gum. • The rate of wilting in treated soil was significantly lower than in untreated soil. [ABSTRACT FROM AUTHOR]

The degree of soil compaction is affected not only by the agricultural machinery but also by the soil physical, chemical, and mechanical properties. We hypothesized that the changes in the soil physical (clay content) and chemical properties (soil organic matter, SOM) due to long-term tillage operations would cause corresponding variations in the soil mechanics properties. The in-situ undisturbed soil samples were firstly adopted to detect soil properties as affected by long-term conventional tillage of Mollisol (black soil), and explore the relationship between soil physico-chemical properties and mechanical properties with 4 different cultivation duration croplands (0, 17, 30, and 40 yr). Then, artificial modified soil samples were further used to verify this relationship and confirm the predominate factor influencing compression-rebound behavior at 3 levels of SOM and clay contents, respectively, at 2 levels of gravimetric water contents. The compression index (C c) and rebound index (C r) were determined using a fast oedometer test. We found that with cultivation duration extending, the clay content and soil bulk density increased, while the SOM, C c and C r gradually decreased. The laboratory simulation tests also showed that the compressibility was higher when SOM or clay content was higher; while the soil resilient capacity was lower when the SOM was lower or clay content was higher. In conclusion, the decrease of SOM and the increase of clay content due to long-term cultivation could increase the risk of soil compaction and weaken its recovery capacity. SOM is predominant in influencing the soil mechanical properties relative to clay content. Maintaining and/or increasing SOM may improve the mechanical properties of arable Mollisols. • Long-term conventional tillage decreases SOM and increases clay content. • Both SOM and clay content affect the compression and rebound behavior. • SOM is predominant in governing the mechanical properties of Mollisols. • SOM acts as an early warning signal for evaluating mechanical properties. • In-situ and indoor simulated test can be complemented and verified mutually. [ABSTRACT FROM AUTHOR]

Sustainable agriculture intensification requires optimization of agriculture resources such as new fertilizers with higher nutrient use efficiency. Biochar has been a promisor alternative not only as a P source but also as a matrix to host P fertilizer to improve its use efficiency by intrinsic features. In our previous work, biochar enriched with P lead to higher sugarcane biomass yield and P use efficiency than conventional P fertilizer in a greenhouse trial, however, the effects of biochar enriched with P in the fate of available-P were not plenty understood. In this work, we investigated the superior P availability after fast-pyrolysis biochar-P fertilizer (BioFert) over the incubation time of 240 days in three distinct soils (sandy, loamy and clayey), evaluating the available-P by an anionic exchangeable membrane (AER) and bicarbonate solution extractions, as also solid P speciation by X-ray Absorption Near Edge Structure (XANES) analysis performed at a Synchrotron source. The AER results showed that available-P in BioFert treatment was, on average, 14% superior in sandy, 56% in loamy, and 72% in clayey soil than triple superphosphate (TSP). XANES results pointed out Al- and Fe-phosphates as the main P-sink for all soils, however both fertilizers introduced P-Ca in the system. The superiority of BioFert was associated with its capacity to buffer the soil pH in values higher than 7 potentially reducing P immobilization. In summary, results support the higher efficiency of BioFert than TSP observed in previous work because it supplies more available P synchronized to plant demand over time. [Display omitted] • Available-P in Biofert was, in average, 14% superior in sandy, 56% in loamy and 72% in clayey soil than TSP • Superiority of Biofert was associated to its capacity to buffer the soil pH. • Al- and Fe-phosphates are the main P-sink for all soils, however both fertilizers introduced P-Ca in the system. • The higher efficiency of Biofert than TSP because it supplies more available P synchronized to plant demand over the time. [ABSTRACT FROM AUTHOR]

Biochar is a beneficial amendment for fine-textured soils. In addition, the interaction of biochar particles with soil components influences the dynamics of water and ions, which is particularly important to remediate salt-affected soils. We investigated the effect of sugarcane bagasse (SB), orange bagasse (OB), and corncobs (CB) biochar on water movement and ion leaching in clayey soil. Non-amended soil (CT) column and soil amended with gypsum (CTG) served as controls. Water infiltration, water flow rate, cumulative leached cations, anions, and exchangeable cations (Ca2+, Mg2+, K+, and Na+) were determined. Biochar increased the water infiltration and water flow rate by 80% and 71%, respectively. The SB and CB treatments increased the ion removal from the soil by 48%, whereas the OB increased the removal by 19%. The OB´s lower surface area and water holding capacity likely influenced its performance. Biochar reduced the Ca2+ and Mg2+ concentration on the soil exchange complex by 44% and 76%, respectively, and increased K+ by 233%. However, the most exciting result was the reduction of exchangeable Na+, 90% in the SB and CB treatments and 50% in the OB treatment. Considering that a high concentration of Na+ on the exchange complex contributes to soil structural degradation, biochar application, especially SB and CB, can potentially improve soil quality and mitigate salt-affected soils. [Display omitted] • All biochars increased the water infiltration and distribution in the clayey soil. • Biochar showed a selective affinity for cations and anions in the soil. • All biochars promoted Ca2+ and K+ leaching. • Sugarcane biochar increased Na+ removal from the soil. • Biochar can potentially improve the soil´s mechanical and hydraulic properties. [ABSTRACT FROM AUTHOR]

The dynamics of soil structure is caused by biotic and abiotic processes, with the onset and magnitude of deformation controlled by soil rheological and mechanical properties. Quantification of such properties is challenging because soil behaviour changes with soil moisture, but common rheological tests are not applicable over all consistency ranges. Here, we combine oscillation shear rheometry with spherical indentation mechanical measurements of soil to obtain greater characterization over a broader range of water contents. The elastic modulus could be measured with either approach, with good agreement found for measured silt and clay textured remoulded agricultural soils. For shear rheometry, plastic viscosity, complex modulus and shear yield stress were also obtained. The spherical indentation provided measurements of hardness and yield stress. Although yield stress was correlated between approaches, the values were orders of magnitude greater for the indenter (0.54 ± 0.33 kPa vs. 34.4 ± 31.2 kPa), presumably because of different loading and failure conditions. At drier water contents, yield stress varied more between the two tests on the clay soil, which corresponded with brittle fracture creating artefacts in shear rheometry measurements. Spherical indentation has not been widely applied to the testing of soils, but the good agreement over a wide water content range between elastic modulus obtained from spherical indentation measurements (0.66 ± 0.27 MPa in wetter zone to 4.45 ± 2.53 MPa in drier zone) and shear rheometry (0.47 ± 0.11 MPa in wetter zone to 2.02 ± 0.98 MPa in drier zone) is promising. Moreover, spherical indentation can be applied to materials varying from brittle to viscous and allows testing on structurally intact soil aggregates. The geometry of a spherical indenter may more closely mimic contacting soil aggregates, so scope exists to extend the approach to explore the slumping of aggregated seedbeds produced by tillage. • Spherical indentation and shear rheometry tests on soil pastes were combined • Testing range extended to broader water contents, from viscous to brittle behaviour. • Elastic modulus measurements similar with both approaches. • Yield stress differed by orders of magnitude between tests. • Future potential to apply spherical indentation to structured soils. [ABSTRACT FROM AUTHOR]

Intensive soil disturbance by conventional tillage and heavy machinery traffic for planting, cultivation, and harvesting operations are the main causes of soil compaction and degradation of soil physical quality in sugarcane fields. However, the adoption of conservation soil tillage practices, such as no-till and reduced tillage associated with traffic control have been proposed as a key strategy to preserve soil physical quality, enhancing water availability and air fluxes. Nevertheless, the effects of reduced tillage associated with traffic control in sugarcane fields are still not well documented. A study was carried out to quantify soil water availability and air flux indicators in two soils with contrasting textures (named Sandy Loam and Clayey soil) under conventional and reduced tillage practices associated with and without controlled machinery traffic in central-southern Brazil. Soil physical parameters such as bulk density, total porosity, air-filled porosity, air permeability, pore continuity index, and the least limiting water range (LLWR) were measured. In both soils, there was no difference between conventional and reduced tillage in bulk density, air permeability, and LLWR. However, reduced tillage with non-traffic decreased bulk density and increased macroporosity, air-filled porosity, air permeability, pore continuity, and LLWR in Sandy Loam soil. In Clayey soil, the bulk density and LLWR did not change between tillage practices, but air permeability and pore continuity index were larger under reduced tillage with non-traffic. These results highlighted that soil disturbance by conventional tillage does not improve the water availability and air permeability during the crop cycle. However, the traffic control is essential to support the adoption of reduced tillage in sugarcane fields, preserving soil water availability and air fluxes for the subsequent ratoons. Reduced tillage and traffic control are two of the most important pillars for reducing soil compaction and promoting sustainability of sugarcane production in Brazil. • Reduced tillage system did not negatively impact the least limiting water range (LLWR) compared to conventional tillage. • Reduced and conventional tillage system sustain similar air-filled porosity and air permeability. • Reduced tillage associated with traffic control increase LLWR in Sandy loam soils. • Traffic control is essential to support the adoption of reduced tillage in sugarcane fields. [ABSTRACT FROM AUTHOR]

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. • Strip-tillage system is an innovative soil tillage for sugarcane plantation. • Deep liming placement is important to reach longevity for sugarcane ratoons in highly weathered clayey soils. • Soil fertility is enhanced by deep liming placement. • Sugar and stalk yield is affected by the relation of lime application and tillage systems. [ABSTRACT FROM AUTHOR]

Prevention of soil compaction requires examining soil mechanical stability. This is usually done by applying the basic concept of the pre-compression stress σ p , assuming a fully elastic behavior for soils being loaded by stresses lower than σ p and a mixture of elastic-plastic behavior being loaded by higher stresses. However, a small cumulative plastic deformation may occur even when the applied stresses is not beyond σ p being indeterminable by current pe-compression test procedures which is not accounting for unloading steps. Therefore, we investigated an alternative approach to simultaneously determine σ p and mechanical elasticity of soil by introducing unloading steps (referred to as release compression, RC). Results were compared to the conventional procedure with continuously increasing loads (continuous compression, CC). In the case of RC, soil settlement was measured both after each loading (RC-L) and after each unloading (RC-U) phases between two consecutive pressures providing two load displacement curves. Oedometer tests were conducted with three different soils comprising different clay contents ranging from 75 to 454 g kg−1. Remolded soil was filled into steel rings and compressed under pre-determined loads in a loading frame providing test samples with known pre-compression stresses of 60 and 120 kPa. The results revealed that σ p values determined under two different applied loading paths (RC vs. CC) were significantly different. Both testing approaches resulted in an overestimation of σ p values based on stress-strain curves which was more pronounced for RC-L compared to CC paths. However, the results from RC-U paths were closer to the CC method than the RC-L path suggesting that if an unloading step is used, RC-U curve should be used to determine σ p values. The results also showed that soil with higher clay contents comprised the lowest σ p value determined from the oedometer tests among all examined soils. From release compression test, we were also able to determine the elasticity of the sample for each loading stress. Among the examined soil samples, the clay soil (with higher clay content) showed the highest elasticity index being less susceptible to soil deformation. • Determination of pre-compression stress (σ p) is stress-path depended. • Continuous multistep stress-path test predicts the known σ p with higher accuracy. • Loading-rebounding (LR) stress-path test predicts the known σ p with lower accuracy. • LR stress-path test allowed to determine soil elasticity for each stress level. • The accuracy of σ p prediction was highest for soils with higher clay contents. [ABSTRACT FROM AUTHOR]

For decades, conservation tillage has been promoted as a measure to increase carbon stocks in arable soils. Since organic farming improves soil quality and soil carbon storage, reduced tillage under organic farming conditions may further enhance this potential. Therefore, we assessed soil organic carbon (SOC) stocks of reduced tillage compared with mouldboard ploughing in nine organic farming field trials in France, Germany, the Netherlands, and Switzerland with the same sampling and analytical protocol. We sampled soil cores until a depth of 100 cm to determine soil carbon stocks that are relevant for climate change mitigation but are often overlooked in tillage studies with shallow sampling depths. The studied field experiments were between 8 and 21 years old and comprised different soil types with clay contents ranging from 10% to 50%. SOC stocks increased with increasing clay-to-silt ratio, precipitation and organic fertiliser input. Across sites, reduced tillage in comparison with ploughing increased SOC stocks in the surface layer (0–10/15 cm) by 20.8% or 3.8 Mg ha−1, depleted SOC stocks in the intermediate soil layers to 50 cm soil depth with a maximum depletion of 6.6% or 1.6 Mg ha−1 in 15/20–30 cm and increased SOC stocks in the deepest (70–100 cm) soil layer by 14.4% or 2.5 Mg ha−1. The subsoil SOC stock increase may be linked to the inherent soil heterogeneity. Cumulative SOC stocks increased by 1.7% or 1.5 Mg ha−1 (0–50 cm, n = 9) and 3.6% or 4.0 Mg ha−1 (0–100 cm, n = 7) by reduced tillage compared with ploughing with estimated mean C sequestration rates of 0.09 and 0.27 Mg ha−1 yr−1, respectively. There was no effect of field trial duration on tillage induced cumulative SOC stocks differences. Under reduced tillage, biomass production was 8% lower resulting in a decrease of crop C input by 6%. However, this reduction may have been outbalanced by increased C inputs from weed biomass resulting from a higher weed incidence in reduced tillage, which warrants further research. Thus, reduced tillage in organic farming has the potential to increase total SOC stocks, while crop management has to be improved to increase productivity. • Reduced tillage in organic farming has the potential for carbon sequestration. • Reduced tillage in organic farming stratifies SOC stocks similarly to no-till. • SOC stocks in subsoils affect the climate change mitigation evaluation of tillage systems. [ABSTRACT FROM AUTHOR]

Many Chinese croplands are suffering from soil acidification, defined as a decrease in soil acid neutralizing capacity (ANC), due to over-application of nitrogen (N) fertilizer and removal of base cations (BCs) in crop harvest. The contribution of fertilization and harvesting on soil acidification rates for different cropping systems is, however, seldom quantified under field conditions. Here, field experiments were conducted on a moderately acid silty clay soil in southwest China to quantify proton (H+) production rates under three fertilization management regimes, including control (non-N), optimized fertilization and farmers' practices (i.e. over fertilization), by measuring the inputs and outputs of major element in three cropping systems, i.e. rice-fallow, rice-wheat and maize-wheat. The maize-wheat cropping system had the highest proton production rates (2.3–10.2 kmol c H+ ha−1 yr−1), followed by rice-fallow (3.2–4.6 kmol c H+ ha−1 yr−1) and rice-wheat (2.2–4.5 kmol c H+ ha−1 yr−1) systems. Crop removal, dominated by straw removal, was the main driver of proton production in all three cropping systems, contributing over 50% of the total H+ production. Compared to the control, N fertilizer application enhanced soil acidification rates among three cropping systems, but had no significant effects on H+ production per kg grain in the rice-fallow and rice-wheat systems. The same was true for the maize-wheat system in case of optimized fertilization, but over fertilization increased both soil acidification rate and H+ production per kg grain, while grain yield was comparable to that with optimized fertilization. The change in soil ANC was dominated by accumulation of SO 4 2− (leading to potential soil acidification) that was mainly added to the soil with superphosphate containing high concentrations of both Ca2+ and SO 4 2− sometimes even causing an increase in the base cation pool, despite BC crop removal. The low contribution of N transformation processes to the total H+ production (3–47%) was due to high denitrification in this specific soil. The soil pH and base saturation did not change significantly among the three fertilization management regimes, largely due to the large BCs pools in the soil. Although the common farmers' practice does not strongly increase proton production in rice-fallow and rice-wheat systems, it still implies a waste of N fertilizer as the excess N input is either enhancing straw production or lost to air in this silty clay soil. Hence, optimized fertilization and localized BCs-rich straw return are suggested to reduce costs of N fertilizer without yield losses and mitigate soil acidification in those systems. [Display omitted] • Soil acidification rates were quantified in three cropping systems in China. • Maize-wheat rotations had higher acidification rates than rice-wheat and rice-fallow. • Optimized N fertilization reduced soil acidification rates without yield loss. • Base cation removal by crop harvesting was the main driver of soil acidification. • Low contribution of N cycle to soil acidification was due to high denitrification. [ABSTRACT FROM AUTHOR]

Modelling of the tillage process by working tools based on the method of discrete elements is currently the most promising. The results of modelling the processing process obtained by the method of discrete elements adequately describe the behaviour of the soil. Due to the large number of physical and mechanical parameters included in the description of contact models of discrete elements, the calibration process takes a lot of time. Thus, we set a research goal - to evaluate the significance of the parameters of the contact model particles in soil modelling by the discrete element method and to obtain nomograms for selecting the parameters of the Hertz-Mindlin contact model particles depending on the humidity of various types of soils. The article presents the results of calibration of the physical and mechanical parameters of the particles of the soil medium model described by the discrete element method. An improved Hertz-Mindlin JKR model was used as a contact model, the model was implemented in the Rocky DEM programme. The following properties of the modelled particles are taken as the studied factors – Poisson's ratio, static and dynamic friction coefficients, Jung's modulus, surface energy, and particle diameter. The detection of the natural slope angle of the soil was carried out for black soils of clay, light loam and sandy loam mechanical composition. The calibration was performed according to the angle of the natural slope. Comparison of the simulation results with field experiments of typical soils made it possible to establish that the nature of the change in the angle of the natural slope of the simulated soil environment is significantly affected by the surface energy and the diameter of the particles. The obtained dependences of the angle of natural slope on soil moisture and surface energy allow determining the parameters for the Hertz-Mindlin contact model as a function of humidity for Black soil zones of clay, light loam and sandy loam mechanical composition. Based on the results of field and model experiments, a nomogram was obtained that makes it possible to select parameters for the contact model - the diameter of soil particles and the value of surface energy depending on humidity and soil type. The obtained values of the parameters of the particles of the soil medium make it possible to simulate the process of tillage, optimize the design and technical parameters of the newly created working parts of tillage machines. • Purpose of the research is to assess the significance of the contact model particles. • Modelling of the tillage process by working tools is currently the most promising. • It is necessary to calibrate the rheological parameters of the contact models. [ABSTRACT FROM AUTHOR]

• Optimal residue retention was 60 % for maize and 10 % for wheat for all soils tested. • Wheat yields were higher for conservation agriculture (CA) than conventional practice (CP). • Maize yields were lower for CA than for CP on clayey and loam soils. • Soil clay content was associated with the duration of yield lags due to CA adoption. • CA increased yield stability for wheat but not for maize for all soil categories. Conservation agriculture (CA) is characterized by zero or minimum tillage, permanent land cover with crop residue or plant growth, and crop rotation. Only a few studies have addressed the impact of soil texture on relative CA:CP productivity, and none have simultaneously evaluated soil texture interactions with optimal residue retention rate. We simulated the interaction effects of soil texture and residue retention on crop yield for CA and conventional practices (CP) for a monsoon-season maize [ Zea mays L.] and dry-season wheat [ Triticum aestivum L.] double-cropping system in the midhills of Nepal. The simulation used 35 years of historical weather data, fifteen soil profile descriptions representing a range of soil texture classes, and variable rates of residue retention. Crop models were calibrated with field data and simulation results evaluated against measured field data from other published studies. Optimal maize residue retention rate was 60 % and optimal wheat residue retention rate was 10 %, regardless of soil texture. At optimal residue retention, CA maize yielded 0.37 Mg ha−1 less than CP on clayey soils and 0.25 Mg ha−1 less than CP on loam soils, equivalent to 5 % and 4 % yield loss, respectively. However, mean wheat yield was greater with CA than CP for all soil textures, with an average yield increase of 0.17 Mg ha−1, or 18 % increase in wheat yield. The time required for CA to produce equivalent maize yields to CP increased by approximately 1.23 yr per % of soil clay. Possible non-linearities exist in the relationship between soil clay and time-to-equivalent maize yield. Wheat yield was more stable, but maize yield less stable, with CA compared with CP for all soil texture categories. [ABSTRACT FROM AUTHOR]