Abstract
Drought is increasingly common due to frequent occurrences of extreme weather events, which further increases soil water repellency (SWR) and influences grain yield. Conservation agriculture is playing a vital role in attaining high food security and it could also increase SWR. However, the relationship between SWR and grain yield under conservation agriculture is still not fully understood. We studied the impact of SWR in 0–5 cm, 5–10 cm, and 10–20 cm layers during three growth periods on grain yield from a soil water availability perspective using a long-term field experiment. In particular, we assessed the effect of SWR on soil water content under two rainfall events with different rainfall intensities. Three treatments were conducted: conventional tillage (CT), reduced tillage (RT), and no-tillage (NT). The results showed that the water repellency index (RI) of NT and RT treatments in 0–20 cm layers was increased by 12.9 %–39.9 % and 5.7 %–18.2 % compared to CT treatment during the three growth periods, respectively. The effect of the RI on soil water content became more obvious with the decrease in soil moisture following rainfall, which was also influenced by rainfall intensity. The RI played a prominent role in increasing soil water storage during the three growth periods compared to the soil total porosity, penetration resistance, mean weight diameter, and organic carbon content. Furthermore, although the increment in the RI under NT treatment increased the soil water storage, grain yield was not influenced by RI (p > 0.05) because the grain yield under NT treatment was mainly driven by penetration resistance and least limiting water range (LLWR). The higher water sorptivity increased LLWR and water use efficiency, which further increased the grain yield under RT treatment. Overall, SWR, which was characterized by water sorptivity and RI, had the potential to influence grain yield by changing soil water availability (e.g. LLWR and soil water storage) and RT treatment was the most effective tillage management compared to CT and NT treatments in improving grain yield.
Highlights
Soil water repellency (SWR) is an intrinsic physiochemical property in coarse- to fine-textured soils under different climates and land uses (Blanco-Canqui and Lal, 2009; Daniel et al, 2019; Diehl et al, 2010)
Sw in the 0–20 cm layer compared with CT treatment during the three growth periods, whereas there was no significant difference between reduced tillage (RT) and CT treatment
We found that NT treatment decreased Sw at the 0–5 cm, 5– 10 cm, and 10–20 cm depths compared to CT treatment during the three growth periods (Fig. 1) due to increment of hydrophobic substances under no-tillage system (González379 Peñaloza et al, 2012; Urbanek et al, 2007)
Summary
Soil water repellency (SWR) is an intrinsic physiochemical property in coarse- to fine-textured soils under different climates and land uses (Blanco-Canqui and Lal, 2009; Daniel et al, 2019; Diehl et al, 2010). The increase of drought stress in the global climate aggravates the SWR (Deurer et al, 2011; Goebel et al, 2011). It can limit soil water absorption rate and reduce water infiltration capacity (Daniel et al, 2019; Zheng et al, 2016), affecting some soil processes (e.g. carbon sequestration, aggregate stability, and soil erosion) and plant growth (Blanco-Canqui, 2011; Li et al, 2019; Liu et al, 2012; Moody et al, 2009). The small degree of SWR, known as subcritical water repellency that occurs when the rate of wetting is decreased by water repellency induced by hydrophobic substances covering the surfaces of soil particles (Tillman et al, 1989), can have a considerable effect on soil structure and hydraulic properties (Hunter et al, 2011; Tadayonnejad et al, 2017), which further affects plant growth and crop production. Studying the mechanism of how tillage practices affect crop yield by changing SWR is critically important for understanding the sustainability of conservation tillage practices
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