长期施肥对农田黑土r-K策略菌群的影响

直接参与土壤养分代谢周转过程的土壤微生物群落是土壤肥力质量的重要衡量指标。本文研究了长期施肥对农田黑土细菌和真菌r-K策略菌群(生态生理功能)的影响。结果表明:施肥处理菌群生长的均匀度和丰富度有所降低,细菌和真菌生态生理指数(EP)降低幅度分别为0.019～0.106和0.023～0.185。各处理K策略菌数量均大于相应的r策略菌。施肥能增加土壤r策略细菌数量,但不利于r策略真菌生长。与CK相比,r-K策略细菌和K策略真菌数量在单施中量有机肥处理中增幅最大;有机肥与化肥配施处理r-K策略细菌和K策略真菌数量高于单施同种化肥处理。在K策略菌占优势下,施用化肥有利于r策略菌比率提高,而有机肥与化肥配施倾向于使K策略菌比率增加。相关性分析表明,K策略菌群与土壤N素呈极显著正相关(P<0.01),可能是影响土壤N素循环的关键菌群。

Effects of long-term fertilization on r-K strategy microbial populations in farmland mollisol

The microbial communities in agricultural soils are responsible for nutrient cycling,and thus,are the important indicators of soil fertility.In this paper,the effects of long-term fertilization on the r-K strategy populations and eco-physiological functional groups of bacteria and fungi in farmland Mollisol were investigated,and the results showed that fertilization decreased the evenness and richness of the fungal and bacterial populations,and the decrements of the bacterial and fungal eco-physiological(EP)indices were 0.019-0.106 and 0.023-0.185,respectively.The amounts of K strategy microbial populations in all treatments were higher than those of r strategy ones.Fertilization caused the increase of r strategy bacteria but the decrease of r strategy fungi.Compared with the control,applying medium amount of manure had the greatest increase of r-K strategy bacteria and K strategy fungi.The amounts of r-K strategy bacteria and K strategy fungi were higher under the combined application of chemical fertilizers and manure than under the application of chemical fertilizers.Under the conditions of K-strategists being predominant,the application of chemical fertilizers enhanced the r-strategy microbial proportion,while the combined application of chemical fertilizer and manure enhanced the ratio of K-strategists.Correlation analysis showed that K-strategy microbial populations had a significant positive correlation(P<0.01)with soil nitrogen content,suggesting that K-strategists might be the key microbial populations in soil nitrogen cycling.