长期施肥对黄土旱塬农田土壤微生物量碳、氮、磷的影响

为研究长期不同施肥方式对土壤微生物量碳、氮、磷含量的影响,以国家黄土高原农业生态试验站长期定位施肥试验为研究对象,选取不施肥(CK)、单施氮肥(N)、单施磷肥(P)、施氮磷肥(NP)、单施有机肥(M)、氮肥配施有机肥(NM)、磷肥配施有机肥(PM)、氮磷肥配施有机肥(NPM)8个处理,应用氯仿熏蒸-浸提法和生态化学计量比,研究了30 a不同施肥方式下土壤微生物量碳、氮、磷含量变化及其与土壤基本理化性状的关系。结果表明:长期施肥较CK处理均能提高土壤微生物量氮、磷含量;与CK相比,施用化肥处理的微生物量碳含量均有所降低,而微生物量氮、磷含量显著提高;除NM处理外,施用有机肥处理的土壤微生物量碳、氮、磷含量较CK处理均显著提高。长期单施化肥、有机肥和化肥有机肥配施处理的微生物量C∶N显著低于CK处理,等量施磷处理(P、NP、PM、NPM)的微生物量C∶P、N∶P均低于CK和其余施肥处理,而NM处理的微生物量C∶P、N∶P显著高于其余处理。冗余分析显示,土壤全氮(F=13.9,P=0.002)对土壤微生物生物量影响最大,解释了微生物量变化的5.3%,各理化性质的影响顺序为全氮全磷pH有机质;相关性分析表明,土壤微生物量碳、磷分别与土壤有机质、全氮、全磷呈显著正相关,土壤微生物量氮与有机质、全氮呈显著正相关。长期单施化肥使土壤酸碱度发生改变,对微生物的生命活动产生抑制作用。而长期化肥配施有机肥能不同程度提高土壤养分含量,促进土壤微生物的生长繁殖,进而增强微生物对碳、氮、磷等元素的吸收利用,对于提高土壤肥力和肥料利用率具有重要意义。

Effects of long-term fertilization on soil microbial biomass carbon, nitrogen, and phosphorus in the farmland of the Loess Plateau, China

Studies on the effect of fertilization patterns on soil microbial biomass carbon, nitrogen, and phosphorus provide scientific basis for improving the efficiency of fertilizer utilization driven by soil microorganisms and understanding the sustainable development of agriculture. Based on the long-term fertilization experiment in the Changwu Agro-ecological Experimental Station, no fertilizer(CK), single application of nitrogen fertilizer(N), single application of phosphorus fertilizer(P), single application of nitrogen and phosphorus fertilizer(NP), single application of organic fertilizer(M), nitrogen fertilizer combined with organic fertilizer(NM), phosphorus fertilizer combined with organic fertilizer(PM), and nitrogen fertilizer combined with phosphorus fertilizer and organic fertilizer(NPM)treatment methods were selected to test the soil microbial carbon, nitrogen, and phosphorus by chloroform fumigation-extraction method and ecological stoichiometric ratio method. Moreover, the relationship between soil microbial properties and soil physical and chemical properties were analyzed in this study. The results showed that long-term fertilization improves the nitrogen and phosphorus content of soil microorganism than CK treatment; compared with CK, chemical fertilizer decreased soil microbial biomass carbon while significantly increasing the microbial biomass of nitrogen and phosphorus; organic fertilizer significantly increased the soil microbial biomass of carbon, nitrogen, and phosphorus than CK with the exception of NM treatment; application of fertilizers significantly decreased the microbial biomass C:N than CK; the treatments with phosphorus application(P, NP, PM, and NPM)decreased C:P and N:P than other treatments, while C:P and N:P of NM treatment significantly higher than other treatments. The redundancy analysis showed that the factors which influence soil microbial biomass was in the order of total nitrogen, total phosphorus, pH, and organic matter; soil total nitrogen had the greatest impact(F=13.9, P=0.002)on soil microbial biomass and explained 5.3% of the change in microbial biomass; the correlation analysis showed that soil microbial biomass carbon and phosphorus were significantly positively correlated with soil organic matter, total nitrogen, and total phosphorus, while soil microbial biomass nitrogen was significantly positively correlated with organic matter and total nitrogen. Long-term application of chemical fertilizers changes the soil pH and inhibits microbial properties in the farmland of the Loess Plateau. Long-term application of chemical fertilizers with organic fertilizers improves soil nutrient content and soil microbial biomass, which facilitate the efficient utilization of nitrogen and phosphorus fertilizers.