The effects of sugar beet rinse water irrigation on the soil enzyme activities

Sugar beet rinse water (SBRW) irrigation is a widely used practice in the northeast of China that reduces the amount of fresh water needed for agricultural irrigation. In addition, soil enzyme activities are important indicators of soil functions such as nutrient cycling and soil fertility. The effects of SBRW irrigation on five types of soil enzymatic activities including invertase, urease, neutral phosphatase, catalase, and polyphenol oxidase were examined at five depths (0-20, 20-40, 40-60, 60-80, and 80-100 cm) of soil. The pre-irrigation and well water (WW) irrigation plots served as background values and control, respectively. The results showed that SBRW irrigation exerted no negative effects on soil enzymatic activities during 2009-2011 experimental period. Invertase, urease, and neutral phosphatase activities significantly increased in soil irrigated with SBRW compared to that of pre-irrigation and that irrigated with WW. Evidence indicates that SBRW irrigation might strengthen the transformation of nutrients such as carbon, nitrogen, and phosphorus and enhance soil nutrients which were required for plant growth. Moreover, catalase activity also significantly rose in soil irrigated with SBRW, suggesting that SBRW irrigation helped remove the adverse effects of hydrogen peroxide. Overall, these results suggest that irrigation with SBRW might be of agricultural interest because of its organic matter concentration and nutrients input, and may be used as a fertilizer source to improve soil quality of irrigated landscapes.