Long-term effects of different surface mulching techniques on soil water and fruit yield in an apple orchard on the Loess Plateau of China

Abstract

Surface mulching has been extensively used for water conservation in dryland orchards. It is critical to choose an appropriate mulching technique for high yield and sustainable development of fruit crops. To solve the impact of water shortage on the production and growth of fruit trees on the Loess Plateau (China), the effects of different surface mulching techniques on an orchard ecosystem were monitored from 2008 to 2015. Different mulching methods, including grass cover (GC), film mulching (FM), straw mulching (SM), and gravel mulching (GM), effectively enhanced the regulatory capacity of soil water reservoir. The soil water content of SM and FM treatments was higher compared with other treatments. With the increase of planting age, the use of deep soil water increased, soil water content showed a decreasing trend, and soil desiccation was partially alleviated. Different mulching treatments improved water use efficiency and apple yield, with the best effect being achieved with GM and SM. GM resulted in lower soil water content, while it increased the proportion of short and medium branches, thus increasing the yield of apples. The water use efficiency was higher and the effect was better for the GM treatment during 2008–2012; thereafter, the benefits decreased due to a mixture of gravel and topsoil. SM produced higher soil water content and apple yield, and its regulation effect on temperature was better than other treatments. Although the soil water content of FM was relatively high, the corresponding yield and water use efficiency were low. The root growth of fruit trees was affected by high summer heat in the FM treatment. Given the high cost of labor required for GM, SM was an appropriate technique to improve the hydrological status and fruit yield of apple orchard soil in the gully region of the Loess Plateau.