长期施肥对新疆灰漠土土壤微生物群落结构与功能多样性的影响

以20a新疆国家灰漠土土壤肥力与肥料效益长期定位试验为平台,采用常规培养法,结合Biolog技术对可培养微生物、生理菌群数量和碳源利用进行测定分析,研究撂荒(CK0)、耕作不施肥(CK)、不同化肥(N、NK、NP、PK、NPK)、化肥配施低量高量有机肥(NPKM1和NPKM2)和秸秆还田(NPKS)等10种处理土壤微生物特征,揭示长期施肥对土壤微生物群落结构与功能多样性的影响。结果表明:(1)可培养微生物:与CK处理相比,CK0处理显著提高了细菌、放线菌和真菌的数量(P0.05),NPKS处理微生物数量则显著降低(P0.05);不同化肥处理的细菌(除PK处理外)、放线菌(除PK和N处理外)数量也有所增加,增幅在8.14%—135.70%和15.30%—44.78%之间;真菌数量(除NK处理外)则有一定幅度的降低;NPKM1和NPKM2处理,微生物数量最高,细菌分别增加了162.20%和173.75%,放线菌增加了34.39%和39.37%,真菌增加了63.33%和488.33%;(2)生理菌群:与CK0相比,CK处理显著提高了自生固氮菌和亚硝化细菌数量(P0.05),显著降低了氨化细菌和纤维素分解菌数量(P0.05);与CK相比,NPKM1和NPKM2处理显著提高土壤中与氮素转化有关的生理菌群数量(P0.05),不同化肥处理和NPKS处理的影响不相同,NPK处理显著高于其余处理(P0.05);(3)微生物碳源利用:微生物活性表现为NK、NPKM1、NPKM2N、NPK、CKPK、NPKSCK0、NP;CK0处理3个多样性指数以及NPKM1、NPKM2和NK处理Shannon(H)指数最高,其余施肥处理差异不显著;糖类、氨基酸类、羧酸类和胺类是微生物利用的主要碳源。(4)聚类分析表明,除NP处理外,施氮处理土壤有较为相似的碳源利用,细菌和真菌与养分之间有较好的相关性,可培养微生物和生理菌群与微生物碳源利用的相关性较差。因此,长期不同施肥对新疆灰漠土土壤微生物群落结构和功能多样性产生了显著的影响,长期耕作不施肥降低了土壤微生物群落结构和功能多样性,不同化肥配合施用对微生物群落的影响不同,NPK及NPK配施有机肥可提高土壤微生物多样性。

Effects of long-term fertilization on diversities of soil microbial community structure and function in grey desert soil of Xinjiang

A long-term (20 years) stationary experiment was carried out in a grey desert soil field of Xinjiang to study the effects of fertilization on soil microbial community characteristics and functional diversity. Traditional microbial cultivation method and Biolog technique were used to analyze soil microbial community, the number of bacterial physiological groups and microbial carbon utilization. Ten fertilization treatments were studied, i.e., abandonment (CK0), cultivated without fertilization (CK), different chemical fertilizer treatments (N, NK, NP, PK, and NPK), NPK and organic materials (NPKM1), NPK and double organic materials (NPKM2), as well as NPK and straw (NPKS). Results showed that, (1) compared with CK treatment, data on the cultivable microorganisms illustrated that the numbers of bacteria, actinomycetes and fungi in CK0 treatment all increased significantly (P < 0.05). Effects of different chemical fertilizer treatments were different. The numbers of bacteria (except PK treatment), and actinomycetes (except PK and N treatments) increased by 8.14-135.70% and 15.30-44.78%, respectively. The numbers of fungi (except NK treatment) decreased by 10.00-38.33%. The numbers of microorganisms were the highest in NPKM1 and NPKM2 treatments. The bacteria numbers of NPKM1 and NPKM2 treatments increased by 162.20% and 173.75%, when comparing with CK treatment. The numbers of actinomycetes increased by 34.39% and 39.37%, while the numbers of actinomycetes increased by 63.33% and 488.33%. However, the numbers of microorganisms decreased obviously (P < 0.05), the numbers of bacteria, actinomycetes and fungi decreased by 14.17%, 21.27% and 63.33%. (2) Studies of soil bacterial physiological groups showed that, the amounts of Azotobacter and Nitrifier in CK treatment were higher than those of CK0 treatment (P < 0.05), but the amounts of Ammoniation and Cytophaga in CK treatment were lower (P < 0.05). Effects of different chemical fertilizer treatments and NPKS treatment were very different. Effect of NPK treatment was obviously the best (P < 0.05). However, NPKM1 and NPKM2 treatments could obviously improve the amount of soil bacterial physiological groups related with N transformation. (3) Carbon utilizations of soil microbial community showed that, the order of soil microbial activities was, NK, NPKM1, NPKM2 > N, NPK, CK > PK, NPKS > CK0, NP. Soil microbial diversity indices of CK0 treatment were the highest. Compared with CK treatment, all fertilization treatments were not significantly different in Simpson index and McIntosh index. Shannon index in NPKM1, NPKM2 and NK treatments were the highest, other fertilizer treatments were not significantly different from, or significantly lower than CK. Carbohydrates, Amino acids, Carboxylic acids and Amines/amides were the main carbon resources for microbial utilization. (4) Cluster analysis indicated that carbon utilizations by soil microbial community for different N treatments were similar (except NP treatment). Correlation between bacteria, fungi and soil nutrient contents were significant, but no significant correlation relationships existed among the cultivable microorganisms, soil bacterial physiological groups and carbon utilizations of soil microbial community. To sum up, the effects of long-term fertilization on diversities of soil microbial community structure and function in grey desert soil of Xinjiang were remarkable. Long-term cultivation without fertilization decreased the diversities of soil microbial community structure and function. Different chemical fertilizer treatments had varied effects. NPK and NPKM treatments could improve the diversities of soil microbial community structure and function.