长期施肥处理对玉米生长期潮土微生物生物量和活度的影响

以1989年建立的中国科学院封丘农田生态系统国家试验站的长期定位试验为平台,研究经18a连续不同施肥处理后玉米季土壤微生物生物量碳氮和微生物活度的动态变化及其与土壤有机碳之间的相互关系,并探讨施肥措施对土壤微生物及其活性的影响。施肥处理包括:(1)有机肥(OM);(2)1/2化肥和1/2有机肥(1/2OM+1/2NPK);(3)氮磷钾肥(NPK);(4)氮磷肥(NP);(5)磷钾肥(PK);(6)氮钾肥(NK);(7)不施肥,即对照(CK)7个处理。结果表明,微生物生物量碳氮和微生物活度在玉米生长期内均有明显的时间变异性,其中微生物生物量碳与微生物活度的动态变化比较一致,其间的极显著相关关系表明潮土微生物生物量碳的变化可以在很大程度上代表土壤微生物活度的变化。施肥制度显著影响微生物生物量碳氮和微生物活度的变化,总体趋势为OM1/2OM+1/2NPKNPKNPPKNKCK,表明OM有利于保持土壤的生物化学环境及促进土壤的生物学活性;与OM处理相比,化学肥料的长期施用有降低土壤微生物生物量和微生物活度的趋势,尤其是缺素处理的表现更为明显,其中以缺磷处理的表现最为严重。土壤微生物生物量碳氮、微生物活度与土壤有机碳变化均呈极显著正相关。

Effect of long-term fertilization on microbial biomass and activity in fluvo-aquic soil during maize growth period

Based on a long-term field experiment initiated in 1989 and conducted in the National Agro-Ecological Experiment Station located in Fengqiu County, Henan Province, China, dynamic changes of microbial biomass C and N, and microbial activity during the growth period of summer maize as related to different continuous fertilization management were investigated in 2007.At the same time, effect of long-term fertilization on microbial biomass and activity and their relationship with soil organic carbon content was also discussed. The experiment was designed to have 7 treatments, i.e. organic manure (OM), half organic manure plus half fertilizer N (1/2OM+1/2NPK), fertilizer NPK (NPK), fertilizer NP (NP), fertilizer NK (NK), fertilizer PK (PK) and control (CK).Results show that temporal variation of soil microbial biomass C and N, and microbial activity was significant during the growth period of summer maize. The dynamics of microbial biomass C and microbial activity were consistent, and their extremely positive correlation suggests that microbial biomass C can be used as an indicator of microbial activity.Fertilization significantly affected soil microbial biomass and microbial activity.The 7 treatments generally showed a decreasing order of OM > 1/2OM+1/2NPK > NPK > NP > PK > NK > CK indicating that organic matter was beneficial to soil biochemical environment and soil microbial activity.Compared with Treatment OM, the other chemical treatments revealed a trend of decreasing soil microbial biomass and weakening microbial activity.It was particularly significant in treatments unbalanced in nutrient, with Treatment NK showing the worst effect, probably because element P is an important element for making up cell wall and membrane for most bacteria.Positive relationship of microbial biomass and enzyme activity with soil organic C was also observed.