长期不同施肥处理水稻土磷素在剖面的分布与移动

ACCUMULATION AND DOWNWARD TRANSPORT OF PHOSPHORUS IN PADDY SOIL IN LONG-TERM FERTILIZATION EXPERIMENTS

稻麦轮作黄泥土施肥试验始于1980年,共布置不施肥、纯化肥、有机肥(猪粪或菜籽饼)、化肥加有机肥、氮肥加秸秆、氮肥加有机肥加秸秆等14种处理.2003年11月麦季取土壤样品分析结果表明:(1)与无肥处理相比,施磷处理和有机肥处理耕层土壤全磷(TP)含量皆有显著增加,并且表现出向下迁移的迹象,有机肥配施NPK化肥处理土壤磷的迁移可达30 cm深度,其余施磷处理均至25 cm.(2)大部分施磷处理在表层0～25 cm内无机磷(I-P)总量发生显著性变化,Ca2-P由于其溶解性强可迁移到30 cm以下,Al-P、Fe-P、Oc-P(闭蓄态磷)的迁移可达25 cm,Ca8-P至20 cm;Ca10-P含量只在有化肥P输入的6个处理的0～15 cm耕层土壤中有显著性增加.(3)土壤有机磷(O-P)含量的变化小于无机磷的变化,只有无机磷配施有机肥的3个处理和仅施PK化肥的处理,其耕层土壤有机磷发生显著性增加.

Objectives of the study were to explore forms, quantities and distribution of soil phophorus in profile of paddy soil as affected by different fertilization patterns in a long-term experiment under a rice-wheat （or rape） cropping system, and to evaluate potential effects of transformation and downward transport of phosphorus on environment. The experiment that has been carrying on since 1980 on a permeable paddy soil （huang ni tu）, is designed to have 14 treatments with 3 replicates. Soil sam- ples were collected from the top soil （0 - 15 cm） and then layers 5 cm apart till 1 m in depth in November 2002. Significant P accumulation was found at the depth of 25 cm for all P treatments but Treatment MNpK（ Manure ＋ fertilizer N ＋ fertilizer P ＋ fertil- izer K） where it was detected at the depth of 30 cm. Inorganic P （I-P） concentrations increased significantly in the soil layer of 0 - 25 cm for most P treatments. Ca2-P moved beneath 30 cm in soil depth, Al-P, Fe-P and Occluded-P （Oc-P） to 25 cm in depth, and Cas-P to 20 cm in depth. Ca10-P contents increased significantly only in treatments with fertilizer P application, showing manure P keeps available longer than fertilizer P. Changes in O-P were smaller than I-P in range. Merely in the plots with manure plus fertilizer P or with fertilizer P and K, the organic P （O-P） concentration in the top soils （0 - 15 cm） increased significantly. Long term of P application exceeding P removal by crops were not economical because more inactive Oc-P and Ca10-P accumulated, and led to P accumulation in the top soil and hence the potential of P loss via surface runoff and leaching that would threaten the quality of surface water and groundwater.