Long-term agro-hydrological simulations of soil water dynamic and maize yield in a tillage chronosequence under subtropical climate conditions

Abstract

Process-based modeling addressing soil tillage effect on soil hydraulic properties is scarce since most assessments focus on static parameters (e.g., bulk density, penetration resistance, total porosity, etc.). Our goals were to (i) simulate the long-term soil water balance and the yield of rainfed maize under a tillage chronosequence, (ii) analyze the duration of the positive impacts of chiseling tillage effects on soil hydraulic properties, and (iii) compare the results produced by the agro-hydrological modeling with the static soil physical properties from earlier studies. A chisel tillage chronosequence was established in an Oxisol, i.e., at the sampling time the soil was under no-till (NT) for 0, 6, 12, 18, and 24 months after chiseling, and under 12 years continuous NT (control). Maize root length density (RLD) and soil hydraulic properties were determined for each treatment (four replications and three soil depths). Soil tillage effect on soil-water regime and maize yield were evaluated using the SWAP model integrated with the crop growth module WOFOST. The simulated scenarios included long-term (30 years) rainfed maize growth in each treatment. The simulation detected significant (P < 0.05) soil tillage effects on crop yield and soil water balance components. Actual crop transpiration (Tact) was promoted in the first crop season after chiseling, increasing crop yield by 14%, but this positive effect of chiseling lasted only one cropping season. Fresh chiseled soil increased Tact, while the 24-month chiseling interval generated larger water loss through runoff. RLD and soil hydraulic properties stratification within soil profile generated different patterns of soil drought stress response during the crop season. Both agro-hydrological modeling (dynamic approach) and individual soil physical properties assessment (static approach) from earlier studies found similar ephemeral positive effects of chiseling on soil physical properties. Nevertheless, agro-hydrological simulations were more effective in detecting soil functioning changes due to agricultural practices. Thus, it is crucial to integrate dynamic and static soil physical assessment when analyzing tillage effects on soil physical properties related to mass and energy transfer in cropped soils.