长期施肥对土壤微生物量及土壤酶活性的影响

 该文以北京国家褐潮土土壤肥力与肥料效益长期监测基地的长期肥料定位试验为平台,研究了长期不同施肥制度对土壤的生物学特性及其土壤酶的影响。主要研究结果：长期撂荒土壤(15年)的有机质和全氮(TN)的含量、微生物量碳(SMB-C)和氮(SMB-N)、土壤的蔗糖酶、磷酸酶和脲酶活性以及SMB-C/SOC(土壤有机碳)和SMB-N/TN比值都高于种植作物的农田土壤;而其代谢商和容重值低于农田土壤。长期施肥的农田(NPK、NPKM 、NPKS和NPKF),其土壤养分含量、微生物量碳和氮以及土壤蔗糖酶、磷酸酶和脲酶活性均高于不施肥的农田(CK);而小麦(Triticum aestivum)-玉米(Zea mays)→小麦-大豆(Glycine max)复种轮作(NPKF)的农田又高于长期复种连作(NPK)的农田;在施肥处理中(NPK、NPKM、NPKS和NPKF),长期化肥与有机肥配合施用的处理(NPKM )的土壤上述指标高于其它施肥处理(NPK、NPKS和NPKF),但其土壤的代谢商、pH值和容重值较低。

BIOLOGICAL PROPERTIES AND ENZYMATIC ACTIVITY OF ARABLE SOILS AFFECTED BY LONG-TERM DIFFERENT FERTILIZATION SYSTEMS

Aims Cropping practices and fertilizer/organic matter application affects the soil microbial growth and activity. In china, only few studies have been conducted on the influence of long-term fertilizer and organic matter with fertilizer application on the soil biological properties. Our objective was to study the changes in soil biological and biochemical characteristics under a long-term (15 years) field experiment involving fertility treatments (inorganic fertilizers and organic matter with fertilizers) and two crop rotation systems.
Methods In 1990, thirteen different treatments were established in the Drab Fluvo-aquic soil in Beijing for the long-term experiment. Six treatments werechosen in this study. Four were in a wheat-maize rotation receiving no fertilizer (CK), mineral fertilizers (NPK), mineral fertilizers plus farmyard manure (NPKM) and mineral fertilizers with maize straw incorporated (NPKS). One was in a wheat-maize/wheat-soybean rotation receiving NPK (NPKF). The other was abandoned arable land (CK0) growing weeds. The amount of chemical fertilizer per year was N 150 kg&;#8226;hm^－2, P₂O₅ 75 kg&;#8226;hm^－2, K₂O 45 kg&;#8226;hm^－2, manure 22.5 Mg&;#8226;hm^－2 and maize straw 2.25 Mg&;#8226;hm^－2. Established methods were used to analyze soil enzymes and soil physical and chemical characteristics. Analysis was done using an integrative method combining correlation and component analyses in SPSS. Important findings The soil organic C (SOC) and total N (STN) content, microbial biomass C (SMB-C) &; N (SMB-N), activities of soil invertase, phosphatase and urease, and the ratio of SMB-C/SOC and SMB-N/STN were found higher in long-term (15 years) abandoned arable land than those in cultivated arable land soils. However, the soil metabolic quotient, pH value and bulk density of fallow soil were lower than those in cultivated arable land soils. The soil nutrient concentration, microbial biomass C &; N, activities of soil invertase, phosphatase and urease, were higher in treatments with fertilizer application
(NPK, NPKM, NPKS and NPKF) compared to no fertilizer application treatment (CK). The above soil parameters were also found higher in wheat-maize/wheat-soybean rotation cropping system compared to continuous wheat-maize cropping system. Among the fertilizer application treatments (NPK, NPKM, NPKS and NPKF), NPKM had relative higher soil nutrient concentration, microbial biomass C &; N, and enzyme activities compared to other fertilizer application treatments. However, the soil metabolic quotient, pH value and bulk density of NPKM were lower than them.