Soil microbial diversity with different fertilizer types and rates in a Phyllostachys praecox stand

Key words: 
• pedology /
• Phyllostachys praecox /
• chemical fertilizers /
• organic fertilizer /
• soil microbial biomass carbon

Abstract: High rates of fertilization and heavy winter mulching commonly practiced in Phyllostachys praecox forest have resulted in several problems，such as bamboo grove deterioration and a decrease in soil quality. A randomized complete block design（RCB） trial with six treatments and three replications was conducted to determine the effects of fertilization on soil microbial biomass and diversity. This trial designed in two parts，treatments 1，2 and 3 with mixture of mineral and organic fertilizer composed of urea，compound fertilizer，manure or rape cake with relative nitrogen value of 2.0，2.0，1.0 （contained 673.5 kg·hm － 2 of N）；treatments 4，5 and 6 with pure mineral fertilizer composed of urea and compound fertilizer with relative nitrogen value of 2.0，1.5 and 1.0 in order，was conducted in May 2005 and soils sampled in December. Compared to soils with a pure mineral fertilizer（treatments 4，5，and 6），soil total organic C（TOC） was significantly higher（P＜0.01） in soils having a mixture of mineral and organic fertilizer（treatments: 1，2，and 3）；with more organic fertilizer （treatments 1 and 2 in contrast to 3） relatively more（P＜0.05） TOC was found. With both mineral and organic fertilizers（treatments 1 and 2），soil microbial biomass C （MBC） was significantly greater（P＜0.01） than single mineral fertilizer（treatments 4 ，5 and 6）. With an increase in the rate of organic fertilizer，soil MBC increased with treatment 1 and 2 significantly higher （P＜0.01） than treatment 3；however，with an increase in the rate of mineral fertilizer used，it decreased with treatment 4 and 5 significantly lower（P＜0.01） than treatment 6. As for soil microbial diversity characterized as average well color development（AWCD），with various rates of organic fertilizer there were no differences between treatments，however with different mineral fertilizer rates AWCD values decreased with treatment 4 significantly lower（P＜0.01） than treatment 5 and 6 at the end of incubation. ［Ch，4 fig. 2 tab. 20 ref.］