Effects of calcium cyanamide on soil microbial properties of intensively managed Phyllostachys violascens stands

Abstract

To study the effect of CaCN2 on soil microbial biomass carbon, the ratio of fungal to bacterial biomass,and soil enzyme activities,and to determine the optimum rate of calcium cyanamide(CaCN2)use in Phyllostachys violascens stands with intensive management,an experiment with a randomized complete block design was established. Soil CaCN2 treatments were 0(control),30,60,90,and 180 g·m-2,each with three replicates. Soil samples were taken 1,3,7,14,and 28 d after CaCN2 application. One-way ANOVA with Duncan's multiple range test was used to compare the difference between samples, and statistical significance was determined at the 5% level(P＜0.05). Results indicated that the 90 and 180 g·m-2 CaCN2 treatments had significantly lower(P＜0.05) soil microbial biomass. Other treatments were inhibited in the short term, but recovered gradually. Compared with bacteria, fungi were more sensitive to CaCN2 with the ratio of fungal to bacterial biomass decreasing significantly(P＜0.05)as the CaCN2 rates increased. As with soil microbial biomass,CaCN2 also inhibited soil enzyme activities. Compared to the control, 28 d after application of CaCN2,soil dehydrogenase,urease,and invertase activities in each treatment were significantly higher(P＜0.05);however, phosphatase activity showed no significant differences. Since low dose of CaCN2(30 g·m-2)had only a short-term effect on soil microbial properties and a high dose(180 g·m-2)had a strong influence,application of 60-90 g·m-2(CaCN2) should be recommended in bamboo stands.