Long-term effects of living grass mulching on soil and water conservation and fruit yield of citrus orchard in south China

To assess and compare the long-term effects of living grass mulching on soil and water conservation and fruit yield, the surface runoff, eroded sediment, soil water content, and fruit yield associated with different mulching patterns, included clean tillage, strip mulching with Paspalum notatum Flugge, full mulching with Paspalum notatum Flugge, strip mulching with Cynodon dactylon (L.) Pers, full mulching with Cynodon dactylon (L.) Pers, were monitored from 2001 to 2015. The results showed that the topsoil physical properties and organic matter content of the orchard were gradually improved with grass mulching time increased, and the full mulching was better than the strip mulching. Full grass mulching and strip grass mulching in the citrus orchard could significantly reduce surface runoff and soil erosion from the first year, and there was no significant difference between different grass mulching patterns in each growth period of fruit trees. In the dry season from August to September, the soil water content of clean tillage treatment was the highest, followed by strip mulching, and the smallest was the full mulching in the soil depth of 0–40 cm. The average fruit yield decreased by 32.15% for strip mulching and 41.72% for full mulching. Combined with the effects of living mulching on soil and water conservation and fruit yield, the strip mulching pattern is the better suitable for citrus orchards in the hilly area of south China. Living mulching with Paspalum notatum Flugge and Cynodon dactylon (L.) Pers had no significant difference in the effects on soil and water conservation and citrus yield. The results provide a valuable guideline for improving the grass interplanting strategies for soil conservation in the red soil hilly areas.