肥料类型对潮土肥际微域内微生物数量和分布的影响

【目的】微生物是土壤中的功能组分,对土壤中有机质的分解和养分转化有重要影响,研究肥际微域内微生物的数量和分布特征,有利于探明肥料类型对土壤养分保蓄和供给的影响。【方法】以华北平原长期有机肥化肥混施(MNPK)和长期不施肥(CK)试验地潮土为研究材料,采用室内土柱培养方法研究了单施化肥(CF)、施用70%化肥+30%有机肥(CFOM)、单施有机肥(OM)和不施肥(NF)时,肥际微域内(<5.0 cm)细菌、真菌和放线菌的分布特征。【结果】与NF相比,施用CF后,CK处理中细菌数量增加84%(P<0.05),MNPK处理中细菌数量则无显著变化(P>0.05); 施用CF对两个处理中真菌数量均无显著影响(P>0.05),但放线菌数量下降了33%和36%(P<0.05)。OM和CFOM施用显著增加了肥际微域中细菌和真菌(P<0.05)的数量; 细菌在近肥源处(0.5 cm和1.0 cm)增幅最大,但真菌在1.0 cm和2.0 cm微域内增幅最大。OM和CFOM施用也显著增加了肥际微域内放线菌的数量(P<0.05),放线菌数量和真菌数量两者的自然对数呈极显著正相关(P<0.01)。【结论】施用有机肥显著提高了潮土肥际微域内细菌、真菌和放线菌的数量,有利于土壤养分的保蓄和持续供给。

Effects of fertilizer type on soil microbes amounts and distributions in fertilizer microsites of fluvo-aquic soil

【Objectives】Microbes are functional components in soils, and play a critical role in soil organic matter decomposition and nutrient transformation. To understand the impacts of fertilizer type on soil nutrient retention and supply, soil microbe amounts and distributions in fertilizer microsites were studied. 【Methods】Fluvo-aquic soils of under 20 a with no fertilization(CK)and combined manure and mineral fertilization(MNPK)were collected for soil column incubation from the experimental farm at the Henan Academy of Agricultural Sciences, Zhengzhou, China. Three fertilizers, namely chemical fertilizer(CF), 70% chemical fertilizer + 30% organic manure(CFOM), and single organic fertilizer(OM)were packed with nylon mesh and placed in the middle of the soil column. Soil microbe amounts and distributions in the fertilizer microsites(< 5.0 cm)were measured. 【Results】Compared to no fertilizer(NF), the amount of bacteria in CF fertilizer microsites increased by 84% in the CK-treated soil, but no significant difference was observed in the MNPK-treated soil. In both CK- and MNPK-treated soils, the amounts of fungus in CF fertilizer microsites were not significantly different than those in NF, while the amounts of actinomycetes in CF fertilizer microsites were significantly decreased 33% and 36% compared to those in NF. The amounts of bacteria and fungus in fertilizer microsites of OM and CFOM were significantly higher than those in NF and CF, and showed an apparent spatial heterogeneity. The amounts of bacteria were the highest in the 0.5 cm and 1.0 cm profiles of the fertilizer microsites, while the amounts of fungus were the highest in the 1.0 cm and 2.0 cm profiles. The amounts of actinomycetes in fertilizer microsites of OM and CFOM were also higher than those in NF(P<0.05), and increases in the amounts of actinomycetes was accompanied by a significant increases in the amounts of fungus. 【Conclusions】The dramatic increases of microbe amounts in the CFOM and OM fertilizer microsites inferred that nutrients were fixed by microbes, and subsequently were conducive to soil nutrient intention and continuous supply.