不同肥料对土壤微生物数量及全氮时空变化的影响

Effect of different fertilization on spatio-temporal variability of soil microorganism and total N

采用等氮技术及原状土柱法研究了尿素（N）、有机肥（OM）和尿素与有机肥配施处理对土壤微生物数量和全氮含量时空变化的影响。结果表明，3种肥料处理的微生物数量均表现为配施〉有机肥〉尿素。同一土层的细菌数量以越冬期最大；真菌数量以抽穗期最大；放线菌数量则随小麦生育期推进逐渐增加，成熟期达最大值。不同生育时期20-40cm土层的细菌、真菌和放线菌数量最大，0～20cm次之，40～120cm随着土壤深度增加逐渐减少。随小麦生育期推进，3种处理0～20cm土层全氮含量逐渐减少。配施处理土壤剖面全氮含量整体变幅较大，其次为有机肥和尿素处理。小麦全生育期各处理0～20cm和0—40cm土层中的全氮量占0—120cm土层全氮总量的比例均表现为配施最高。相关性分析表明，除尿素处理拔节期的土壤细菌、真菌、放线菌数量，有机肥处理扬花期的放线菌和灌浆期细菌数量与土壤全氮含量相关性不显著外，各处理各生育期微生物数量与全氮含量均显著或极显著相关。

Three fertilizer treatments, urea, organic fertilizer and a mixture of the two, were studied in an experiment to determine the spatio-temporal variability of soil microorganisms and total N, using equal-nitrogen technique and soil-column method. The resuhs show the order of the number of microorganisms under the three treatments is as follows ： combined-fertilizer treatment 〉 organic fertilizer treatment 〉 urea treatment. In all the treatments, the maximum number of bacteria in a single soil layer occurs in over wintering stage, and that for fungi is in the booting stage. The number of actinomycetes increases with growth, and reaches the maximum during mature stage. The number of bacteria, fungi and actinomycetes in 20 - 40 cm soil layer is highest, followed by 0 -20 cm layer, and least in 40 - 120 cm soil layer where a decreasing trend with increasing soil depth over different growth stages of winter wheat is observed. Soil total N content decreases with increasing soil depth in all the treatments at all growth stages of winter wheat, while that for 0 - 20 cm soil depth decreases as growth of winter wheat advances. Total N content along soil profile has the biggest range under combined-fertilizer treatment, followed by organic fertilizer treatment, and finally urea treatment. The highest proportion of total N in 0 - 20 cm and 0 - 40 cm soil layers to that in the entire 1.2 m soil layer is observed under combined-fertilization treatment. Correlation analyses resuhs show that with the exception of the number of bacteria, fungi and actinomycetes in urea treatment at jointing stage and the number of actinomycetes at anthesis stage, the number of bacteria at filling stage under organic fertilizer treatment, the number of soil microorganism is significantly （P 〈 0.05 or P 〈 0.01 ） corrlated with total N content under the three treatments at all growth stages.