磷的高效利用问题一直是国内外农业研究的热点，然而，关于油稻两熟田磷肥整体利用效率的长期定量研究还鲜见报道。本研究拟采用长期定位试验与EPIC模型模拟相结合的方法，定量研究长期（30年）磷肥投入和秸秆覆盖对油稻两熟田磷素运移规律的影响，明确磷肥的后效效应，探索提高磷肥整体利用效率的途径与方法。1）比较不同处理土壤中各形态磷素含量及剖面分布的动态差异，研究长期磷肥投入和秸秆覆盖对油稻两熟田磷素存在形态及其动态变化规律的影响，重点明确长期施磷和秸秆覆盖对磷素有效性及土层分布的影响。2）比较不同处理下作物组织中磷素含量，结合土壤磷素含量等指标，研究长期磷肥投入和秸秆覆盖对油稻两熟田磷肥整体利用效率的影响，重点明确磷肥的后效效应。3）基于EPIC模型，优化传统磷肥调控措施，探索适宜川东北丘陵区油稻两熟田的磷肥整体调控措施，为实现磷素的高效可持续利用提供必要理论依据和实践基础。

Phosphorus using efficiency is one of the continuous hotspots in agricultral science，however few researches (Longterm and Quantitative Research) has been carried out for the whole usiing efficiency of phosphorus in oilseed rape-rice field. .By integrating world wide results and private practical basis, a new integrating approach with both field experiments and computer modeling (EPIC model) will be used in this research. Objectives of this research are 1)To clarify the impacts of longterm phosphorus input and straw mulching on phosphorus transporting and its using efficiency. 2) To point out some advices for farmers to use phosphorus wholely and effectively in oilseed rape-rice field..Experiment in this research will include two parts, field experiment and computer simulation (by EPIC model). 1) Phosphorus,forms and content,in soil will be compared among different treatments, then the effect of longterm phosphorus input and straw mulching on phosphorus changes and effectiveness will be analyzed on the basis of this comparison. More stress will be put into the research of phosphorus distribution and its efectiveness. 2) Phosphorus content of different tissues will be compared among diffenent treatments. Then the whole using efficiency of phosphorus will be researched based on this analizing results and phosphorus content in soil. More attention will be taken into the aftereffect of phosphorus in oilseed rape-rice field. 3) The impacts of longterm (30 years) phosphorus input and straw mulching on phosphorus transporting and its using effeciency will be researched based on simulation results of the EPIC model. At last, some phosphorus regulating methods for oilseed rape-rice rotation system will be point out in the hilly region of Northeast Sichuan Province.