太湖地区水稻土磷素径流流失及其Olsen磷的“突变点”

Research on Phosphorus Runoff Losses from Paddy Soils in the Taihu Lake Region and Its Olsen-P "Change-point"

采用田间小区试验的方法,研究了太湖地区爽水型水稻土(无锡安镇)和囊水型水稻土(常熟)磷素地表径流流失状况及其与土壤Olsen P浓度的关系。结果表明:在常规施磷处理水平下,爽水型水稻土2000～2001年度的地表径流磷(TP)流失量为603.2g/(hm2·a),2001～2002年度为1148.9g/(hm2·a);而囊水型水稻土2000～2001年度地表径流磷流失量为679.5g/(hm2·a),2001～2002年度为1350.3g/(hm2·a)。麦季土壤磷的径流流失量均大于稻季磷的径流流失量。施肥量对土壤磷素径流流失有显著的影响。爽水型水稻土和囊水型水稻土土壤磷素径流流失各存在一个突变点,分别为32和26mg/kg。两种水稻土突变点的差异可能与它们的质地和有机质含量不同有关,同时也表明囊水型水稻土土壤磷更易流失,这与囊水型水稻土土壤磷素年径流流失量大于爽水型水稻土的结果是一致的。

A field plot experiment was conducted on two types of paddy soils,the permeable paddy soil in the Anzhen site and the waterlogged paddy soil in the Changshu site,in the Taihu Lake Region from June 2000 to June 2002 to explore phosphorus(P) loss by runoff and by drainage flow and its relation to Olsen-P concentration in the topsoil.The results showed that,under the conventional P application rate of P_(30)/P_(20),total P(TP) loss rate by runoff and by drainage flow was 603.2?g/(hm^2·a) during the 2000～2001,lower than that during the year 2001～2002 which was 1?148.9?g/(hm^2·a) in the permeable paddy soil.While in the waterlogged paddy soil at the Changshu site,it was 679.5 and 1?350.3?g/(hm^2·a) during the 2000～2001 and 2001～2002,respectively.Of the average annual TP losses from P_(30)/P_(20) plots in two years,63% was in wheat season and only 37% was in rice season in the peameable paddy soil,while in the waterlogged paddy soil more than 80% was in wheat season.Phosphorus application rate significantly affected TP losses by runoff or by drainage flow(p<0.01).The change-point of phosphorus losses by runoff is 32?mg/kg in the permeable paddy soil,greater than in the waterlogged paddy soil(26?mg/kg).This indicated that P loss by runoff in the waterlogged paddy soil would be probably easier than that in the permeable paddy soil.