Mulch application in fruit orchards increases the persistence of soil water repellency during a 15-years period

Application of crop residues to cultivated soils combined with no tillage are management practices used to improve water management, increase soil fertility, crop production and soil erosion control. Conservative practices as mulching and no-tillage increase soil organic matter input in soils and contribute to reduce the soil hydrological response, but also increase soil water repellency. Water repellency is a property of soils that reduces infiltration rates. In this research, we have studied the effect of no-tillage and mulching at different rates (1–4, MR1; 5–8, MR2; and 9–12 Mg ha−1 year−1 wheat straw residues application, MR3) versus conventional tillage with no mulching, during a range of treatment periods (1–15 years) in Southern Spain. Soil water repellency (SWR) and organic matter content were analyzed and rainfall simulations were performed to study the impact of management in the hydrological soil response (time to ponding, Tp; time to runoff, Tr; and runoff rate). Subcritical SWR developed in MR1 soils, and slight SWR was observed in MR2 and MR3 soils after a few years of treatment. Subcritical or slight SWR induced significant changes in Tp and Tr, which increased mainly in MR1 soils, but increased SWR observed in MR2 and MR3 soils reduced the positive impact of organic matter and contributed to accelerate ponding and runoff flow.

► Soil water repellency was studied in cropped soils under different mulching rates.
► Low mulching rates reduced runoff rates when compared to conventionally tilled soils.
► Slight water repellency tended to increase runoff rates after high mulching rates.
► Soil water repellency may counteract positive effects induced by organic matter.