氮磷添加对内蒙古温带典型草原土壤微生物群落结构的影响

Effects of nitrogen and phosphorus addition on soil microbial community composition in temperate typical grassland in Inner Mongolia

选取内蒙古温带典型草原,进行连续6a氮磷添加试验,采用土壤特征微生物PLFA生物标记技术,研究6个氮添加水平N0(0 kg N hm-2a-1)、N1(56 kg N hm-2a-1)、N2(112 kg N hm-2a-1)、N3(224 kg N hm-2a-1)、N4(392 kg N hm-2a-1)、N5(560 kg N hm-2a-1)和6个磷添加水平P0(0 kg P hm-2a-1)、P1(15.5 kg P hm-2a-1)、P2(31 kg P hm-2a-1)、P3(62 kg P hm-2a-1)、P4(93 kg P hm-2a-1)、P5(124 kg P hm-2a-1)对土壤特征微生物PLFA生物标记数量和土壤微生物群落结构的影响。结果表明:(1)随氮添加量增加,土壤微生物总磷脂脂肪酸(PLFA)含量和土壤细菌PLFA生物标记数量、放线菌PLFA生物标记数量呈上升趋势,土壤G+/G-呈增加趋势;各氮添加水平对土壤真菌PLFA生物标记数量无显著差异,随氮添加量增加,土壤真菌/细菌比降低。(2)随磷添加量增加,土壤总磷脂脂肪酸(PLFA)含量、土壤细菌PLFA生物标记数量、放线菌PLFA生物标记数量、真菌PLFA生物标记数量及真菌/细菌比值呈先上升后下降趋势,均以P3水平(62 kg P hm-2a-1)处理最高,说明适宜的磷添加对内蒙古温带典型草原土壤微生物繁殖和菌落结构有显著影响。

Nitrogen and phosphorus addition is a main measure to improve plant growth and soil properties. However, little is known about the relationship between nitrogen and phosphorus addition and soil microbial community composition in temperate typical grassland in Inner Mongolia. In this paper, two single factor experiments were conducted respectively to investigate the influence of different nitrogen rates （0, 56, 112, 224, 392, 560 kg N hm-2 a-1） and different phosphorus rates （0, 15.5, 31, 62, 93, 124 kg P hm-2 a-1） addition on soil microbial community composition of temperate typical grassland in Xilinguole, Inner Mongolia, China. During the 6-year experimental period, increasing nitrogen rate increased the total numerical values of PLFA biomarker, actinomycete PLFA biomarker, bacteria PLFA biomarker, and the ratios ofG＋/G-, but did not have significant effect on the numerical values of fungal PLFA biomarker. Increasing nitrogen rate decreased the ratios of fungi/bacteria. Total numerical values of PLFA biomarker, bacteria PLFA biomarker, actinomycete PLFA biomarker, fungi PLFA biomarker and fungi PLFA biomarker/bacterial PLFA biomarker ratio had the highest values at the P3 （62 kg P hm-2 a-1） phosphorus addition treatment. The results indicated that nitrogen and phosphorus addition could greatly affect soil microbial community composition in temperate typical grassland.