Abstract

Using laboratory measurements and numerical simulations, we studied the long-term impact of contrasting tillage and cover cropping systems on soil structure and soil hydraulic properties. Complete water retention and conductivity curves for top (0–5 cm) and subsurface (20–25 cm) samples were characterized and contrasted. Plot-level properties of water storage and retention were evaluated using numerical simulations in HYDRUS-2D software. Soils under no-till (NT) and cover cropping (CC) systems showed an improved soil structure in terms of pore size distribution (PSD) and the hydraulic conductivity (K) under these systems led to increased infiltration rate and water retention. The conventional measurement of water content at field capacity (water content at −33 kPa suction) and the associated plant available water (PAW) showed that NT and CC plots had lower water content at field capacity and lower PAW compared to standard-till (ST) and plots without cover crop (NO). The numerical simulations, however, showed that NT and CC plots have higher profile-level water storage (albeit marginal in magnitude) and water availability following irrigation. Because the numerical simulations consider retention and conductivity functions simultaneously and dynamically through time, they allow the capture of hydraulic properties that are arguably more relevant to crops. The changes in PSD, water conductivity, and water storage associated with NT and CC systems observed in this study suggest that these systems are beneficial to general soil health and improve water retention at the plot scale.

Highlights

  • 30 Improving soil health—the vitality of a soil in sustaining the socio-ecological functions of its enfolding land (Janzen et al., 2021)—is one of the main challenges of our time as we grapple with the demands of growing population and changing climate

  • Soils under no-till (NT) and cover cropping (CC) systems showed an improved soil structure in terms of pore size distribution (PSD) and the hydraulic conductivity (K) under these systems led to increased infiltration rate and water retention

  • The changes in PSD, water conductivity, and water storage associated with NT and CC systems observed in this study suggest that these systems are beneficial to general soil health and improve water retention at the plot scale

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Summary

Introduction

30 Improving soil health—the vitality of a soil in sustaining the socio-ecological functions of its enfolding land (Janzen et al., 2021)—is one of the main challenges of our time as we grapple with the demands of growing population and changing climate. Conservation agriculture is credited with myriad beneficial changes to soil hydrology, including increases in 55 macroporosity (Abdollahi et al, 2014; Burr-Hersey et al, 2017), water storage (Liu et al, 2019; Basche et al, 2016a; Duchene et al, 2017; Finney et al, 2017; Ashworth et al, 2017), and infiltration (Hudson, 1994; Johnson and Hoyt, 1999; Basche and DeLonge, 2017). Several studies have noted the critical lack of field studies and the need for evaluation of long-term effects of conservation agriculture on the soil physical and hydraulic properties and soil hydrological processes (Peña-Sancho et al, 65 2016; Basche and DeLonge, 2017; Blanco-Canqui and Ruis, 2018; Bacq-Labreuil et al, 2019). We evaluated the properties of soil cores collected from the California Conservation Agricultural Systems Innovation (CASI) Center, where plots have been under a mix of reduced tillage and cover crop treatments since 1999. We aimed to test whether conservation agriculture results in significant alterations in water 70 retention, pore size distribution, density, hydraulic conductivity as well as static and dynamic field capacity

Methods
Sampling
Soil porosity determination
Results and Discussion
Bulk density
Findings
Conclusion
Full Text
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