长期不同施肥处理红壤旱地剖面养分分布差异

【目的】 研究长期不同施肥措施下红壤旱地的培肥效果、养分迁移特征以及环境风险，对制定红壤旱地合理的养分管理和培肥技术，促进畜禽粪便的循环利用具有重要意义。 【方法】 依托始于1986年的红壤旱地肥料定位试验，选取不施肥 (CK)、氮磷钾肥配施 (NPK)、2倍氮磷钾肥配施 (2NPK)、有机肥 (OM) 和有机肥和氮磷钾肥配施 (NPKM) 5个处理，采集0—10 cm、10—20 cm、20—40 cm、40—60 cm、60—80 cm、80—100 cm土壤样品，分析了pH值、有机质及氮磷钾养分含量。 【结果】 连续施肥28年后，红壤旱地土壤有机质、全氮、碱解氮、全磷、有效磷、速效钾等含量均随着土壤深度增加逐步降低。与对照相比，施用有机肥显著提高了0—40 cm土壤的pH值，其余处理pH有所下降。长期施用化肥后，红壤旱地土壤有效磷、全磷、碱解氮和全氮在0—20 cm耕层累积，土壤速效钾的累积则达到40 cm深；与化肥处理相比，有机肥和有机无机肥配施处理0—40 cm土壤的全氮、碱解氮、速效钾、有效磷和全磷的含量显著增加，土壤全氮和碱解氮的下移累积达到40 cm，而土壤全磷和有效磷的下移累积则达到了60 cm。红壤旱地长期施用猪粪等有机肥主要增加了0—40 cm耕层土壤的磷素累积，而在剖面80 cm以下未表现出明显累积现象。 【结论】 长期施用化肥 (28年)处理养分主要在0—20 cm红壤旱地耕层土壤累积，而长期施用有机肥或有机无机肥配施还可以明显提高20—40 cm土壤养分含量，养分下移累积作用明显。此外，红壤旱地长期施用有机肥可以缓解耕层土壤的酸化、提高耕层土壤肥力水平，是增加培肥深度的有效措施，但是长期施用猪粪导致的氮磷下渗深度增加可能引起的环境风险也应引起重视。

Differences of soil nutrient distribution in profiles under long-term fertilization in upland red soil

【Objectives】 Different fertilization measurements affect the moving down behaviors of soil nutrients in upland red soil. Clarifying the fertilization effects on improving soil fertility and possible environmental risk is necessary for formulating reasonable nutrient management and promoting the utilization of livestock and poultry manure. 【Methods】 Based on a 28-years' long-term fertilization field experiment in upland red soil since 1986, soil samples were collected from five treatments, including no fertilizer (CK), nitrogen, phosphorus and potassium fertilization (NPK), double usage amount of NPK fertilizers (2NPK), piggery manure (OM), and NPK plus manure (NPKM). Soil pH, the contents of organic matter, the total and available N, P and K were analyzed for every 20 cm depth of soil till 100 cm. 【Results】 The contents of soil organic matter, total N, alkali hydrolysable N, total P, available P and readily available K decreased gradually with the increase of soil depth. The soil pH showed the trend of increase first and then decrease with the increase of soil depth. Manure significantly increased soil pH of 0–40 cm depth. The contents of total K remained stable in 0–100 cm soil layers. In NKP and 2NPK treatments, the soil total N, alkali hydrolyzable N, total P and available P were mainly concentrated in the 0–20 cm soil layers, the readily available K reached 40 cm soil layers. Compared to NPK and 2NPK, soil nutrient contents moved deeper in treatments of NPKM and OM, the soil total N and alkali hydrolyzable N reached 40 cm in depth, while the soil total P and available P reached 60 cm. Pig manure increased the P accumulation in the depth of 0–60 cm, and there was no accumulation below 80 cm. 【Conclusions】 The long-term chemical fertilization mainly causes soil nutrients accumulation in the topsoil of 0–20 cm, while pig manure (with or without chemical fertilizer) causes nutrients accumulation in the 0–40 cm soil depth, promotes down-movement of phosphorus even to the 60 cm soil depth. Comprehensively, application of manure could alleviate soil acidification, improve soil fertility and cultivate fertile deep soil. Although the downward leakage depth of N and P caused by long-term application of pig manure has not reached 80 cm, more attention should be paid to its potential environmental risk.