长期施用化肥、猪粪和稻草对红壤水稻土化学和生物化学性质的影响

2005年和2007年分别从望城县已建立27年的肥力定位试验田内采集土壤样品，测定土壤有机碳（TOC）、全N、速效N、速效P、微生物生物量碳、氮（C_mic、N_mic）及土壤呼吸和酶活性，研究长期施用化肥、猪粪和稻草对土壤化学和生物化学性质的影响.结果表明：长期施用化肥、猪粪和稻草处理的土壤pH值与试验前相比均有所下降，电导率（EC）变化不大.化肥与猪粪、稻草配施处理的TOC、全N、速效N、速效P、土壤呼吸、C_mic、N_mic和酶活性均高于不施肥（CK）和单施化肥处理；化肥与猪粪、稻草配施处理的水稻产量也高于单施化肥处理.在研究期间，NK化肥与猪粪、NPK化肥与稻草配施处理的C_mic/TOC大于相应的单施化肥处理.各处理土壤生物化学性质与TOC和养分含量呈正相关(P<0.01).猪粪、稻草与化肥长期配合施用能显著改善土壤化学和生物化学性质，提高土壤质量和土壤肥力.

Effects of long-term application of chemical fertilizer, pig manure, and rice straw on chemical and biochemical properties of reddish paddy soil

In 2005 and 2007, soil samples were collected from a 27-year experimental field in Wangcheng County of Hunan Province to study the effects of long-term application of chemical fertilizers (CF) and their combinations with pig manure (PM) and rice straw (RS) on the chemical and biochemical properties of reddish paddy soil (Typic Haplic-Stagnic Anthrosis). Under the fertilization, soil pH had somewhat decrease, and soil conductivity changed less, compared with those before the experiment was installed. The contents of soil total organic carbon (TOC), total N, available N and P, and microbial biomass C (C_mic) and N (N_mic), soil respiration rate, and activities of soil urease, acid phosphatase, invertase, and dehydrogenase were all higher in treatments CF+PM and CF+RS than in treatments CF and CK, and the C_mic/TOC ratio was higher in treatments CF+PM and CF+RS than in treatment CF. During the study period, applying CF alone induced a lower rice yield than the application of CF plus PM or RS.There were significant positive correlations (P<0.01) between soil biochemical properties and soil TOC and nutrient contents. It was concluded that long-term application of CF combined with PM and RS improved the soil chemical and biochemical properties, being an effective measure to improve the quality and fertility of reddish paddy soil.