两种培肥途径下红壤磷素储供能力的动态变化

Dynamic Changes of Phosphorus Fertility Supply and Reserves in Red soils under Two Fertilization Approaches

以长期施肥的旱地红壤为材料,研究了单施无机肥、有机-无机配施两种途径下,红壤的磷库储量及其供磷能力的动态变化。结果表明：两种培肥途径均可以稳定并提高红壤全磷和有效磷含量,化学磷肥的合理施用可在4~5a内重建红壤磷库,使之达到磷素肥沃水平（Olsen-P约为20mgkg-1）,而配施猪厩肥只需2a时间,配施花生秸秆的效果不显著。两种培肥途径均可以提高红壤中各形态无机磷含量,尤其是可以显著增加最有效的Al-P含量,从而大大增强了红壤的供磷能力。当红壤磷素的自然供给能力降至最低时,如NK处理的全磷量小于0.3gkg-1时,土壤中所有不同形态的磷（包括Olsen-P）都可视为无效或者说土壤无有效供磷能力。

Dynamic changes of phosphorus （P） fertility supply and reserves in red soils under long- term （20 years） fertilization were studied. Application of chemical fertilizer alone and combined with organic- chemical fertilizers were two basic approaches to improve P pool reserves and its supply in red soils by means of increasing the total soil phosphorus and available soil phosphorus. Results showed that to build up soil P fertility to fertile P level （Olsen- P 20 mg P kg-1） required 4 - 5 years by applying phosphate fertilizer alone, and the duration was only two years when organic- chemical fertilizers were applied simultaneously, but it was not significant when peanut straws were applied simultaneously. Long- term application of phosphate fertilizer could increase the content of various inorganic phosphorus in red soil, especially for soil Al- P as the most available soil P. The P supply capacity of red soil could be greatly enhanced. When the P- supplying capacity of red soil decreased to a constant low value （for example, the soil total P in Treatment NK was below 0.3 g kg-1）, all soil P （including Olsen- P） could be regarded as unavailable fractio nation to plant, which means that the soil had not have any capacity to supply P to plant.