湿润速率对中性紫色水稻土磷素淋溶动态的影响

Dynamic Characteristics of Phosphorus Leaching in Neutral Purple Paddy Soils Effected by Rewetting Rate

为了研究土壤湿润速率对土壤磷素淋溶的影响,以国家紫色土土壤肥力与肥效监测基地的长期定位试验为研究对象,开展了室内磷素淋溶模拟分析以及田间原位监测试验。结果表明:自然存水条件下的水稻土磷素淋溶主要发生在2h快速湿润速率下,有机肥配施氮磷钾肥和单施氮磷钾肥处理最高全磷(TP)浓度相当,比无肥和单施有机肥处理高14.97%,土壤湿润后的微生物生物量碳在2h时出现最低值,且随湿润速率的减缓逐渐升高,但土壤在不同湿润速率下淋洗出的磷浓度与土壤微生物生物量碳含量间无线性负相关,说明该土壤湿润后淋洗出的磷主要来源于土壤胶体,表明吸附的磷或者土壤溶液中的磷淋洗程度主要取决于土壤磷素状况;田间原位监测试验指出,经过48h后田表水TDP、可溶性有机磷(DOP)、钼酸反应磷(MRP)浓度显著降低,MNPK、NPK、M、CK处理的TDP浓度分别降低了32.66%,15.76%,12.83%,57.07%;DOP在室内淋洗液和田间田表水中所占的比例均高于MRP,有机肥配施氮磷钾肥增强了稻田磷素淋失的风险,农业生产过程中应注重有机肥的施用。

Investigate the effects of rewetting rate on phosphorus leaching in neutral purple paddy soils under a condition where it always filled with irrigation water in Three Gorges Reservoir Areas,four kinds of neutral purple soils of different fertilizer treatments were analyzed by using simulate lab test and detecting experiment in situ.The results showed that：The P leaching events of all fertilizer treatments mainly occurred at rapid wetting rate,and TP leaching concentration reached the maximum at 2h where MNPK treatment had similar TP concentrations with NPK treatment and MNPK treatment 14.97% higher than CK,M treatments.The lowest content of MBC appeared at the rate of 2hand the content of MBC increased with the slowing of rewetting rate.However,as the slowing of rewetting rate,negative linear correlation were not observed between MBC contents and TP,TDP,DOP as well as MRP in leachate（P〈0.05）after moist soils were rewetted,so it could conclude that the phosphorus leached from moist soils not derived from soil microorganism but from soil colloid and soil solutes,and leaching degree was up to soil phosphorus accumulation.Detecting experiment in situ indicated clearly that the TDP,DOP and MRP concentrations of soil surface water significantly decreased after 48 h,and TDP concentrations of MNPK,NPK,M,CK treatments decreased by 32.66%,15.76%,12.83%,57.07%respectively.The ratio of dissolved organic phosphorus（DOP）to total dissolved phosphorus（TDP）was higher than ratio of molybdate reactive phosphorus（MRP）to TDP in leachate as well as in surface water of paddy fields.Organic manure with NPK fertilizer（MNPK）treatment enhanced the risk of phosphorus leaching.Then it came to conclusion that organic phosphorus was the important source of agricultural non-point pollution,and the intelligent use of organic manure was of great important to agricultural production.