Effects of mulching patterns on root growth and soil environment of Lycium barbarum

Lycium barbarum is the main commercial crop across arid lands in northwestern China. In order to further understand the effects of different mulching patterns on root growth and soil environment, a mulching experiment was conducted at the Agricultural Demonstration Site in Gulang, Gansu Province (37.30°N, 103.29°E). The experiment consisted of four treatments —— plastic film mulching from spring of the second year (PMs), plastic film mulching from autumn of the first year (PMa), stalk mulching from spring of the second year (SMs) and stalk mulching from autumn of the first year (SMa). Root physiological characteristics and distribution, soil water storage and temperature of three-year-old plants of 'Ningqi 1' L. barbarum were studied. The results showed that both plastic film mulching and straw mulching improved soil water storage, and autumn mulching was better for winter soil water storage, which increased to 117.1% and 114.4% of that of CK (no mulching), respectively, in the next early spring. PMa and SMa respectively increased average temperature of soil by 18.0% and 7.1%, while PMs and SMs increased average temperature of soil by 6.4% and 2.3%, compared with CK. Both plastic film mulching and straw mulching improved annual specific conductivity of root, and the change in specific conductivity was most significant under PMa, reaching 109.95% of CK. Also change in specific conductivity was smallest in FMs, 100.3% of CK. While mulching treatment increased root activity in low temperature seasons, it decreased root activity in high temperature seasons. Change in root/shoot ratio was most significantly under plastic film mulching, with PMa and PMs values of 87.42% and 90.35% of that of CK, respectively. Within 0-20 cm soil layer and 40-60 cm horizontally around the plants, the largest proportion of fine roots was under PMa (reaching respectively 133.5% and 116.7% of CK) and the smallest proportion was under FMs. It suggested that mulching pattern was closely related with root growth and distribution. Also soil moisture changed soil environment and root distribution. Mulching was good for water and nutrient utilization in shallow soils and in horizontal far from Lycium barbarum.