中文摘要：

对太湖地区稻麦轮作黄泥土进行23a长期施肥试验，设14种处理：不施肥（C O）、氮肥（C N）、氮钾肥（C NK）、氮磷肥（C NP）、磷钾肥（CPK）、氮磷钾肥（CNPK）、稻草加氮肥（CRN）、有机肥（MO）、有机肥加氮（MN）、有机肥加氮钾（MNK）、有机肥加氮磷（MNP）、有机肥加磷钾（MPK）、有机肥加氮磷钾（MNPK）、有机肥加稻草加氮（MRN）。结果表明：（1）与无磷处理比较，耕层（0-15cm）全磷（TP）、有效磷（Olsen-P）和无机磷（I-P）含量均显著增加，有机磷（O-P）含量仅在MNP、MPK、MNPK和CPK处理中显著增加；耕层以下O-P无显著增加，MNPK、MNP、MRN和MN处理中I-P下移可达25cm，而MNPK处理中TP及MNPK、CNP处理中Olsen-P下移可达30cm；耕层磷素积累量及磷素下移深度与施磷量、施肥模式（化肥磷、有机肥磷；单施、混施）和磷素形态有关。（2）有机肥I-P下移深度比化肥I-P深。（3）不同施肥处理对水体环境存在不同的污染风险，其中以MNPK处理下土壤磷素对水体环境的污染风险最大；地表水的污染风险大于地下水，稻季的污染风险大于麦季，丰水年的污染风险大于平水年。

英文摘要：

The phosphorus distribution in paddy soil and its pollution risk to water body were studied in a 23-year longterm experiment,which was designed to have 14 treatments with 3 replicates and has been carried out under a rice-wheat cropping system. The 14 treatments consisted of no fertilizer （ CO）, N（ CN ）, NK（ CNK ）, NP（ CNP）, PK（ CPK ）, NPK（ CNPK ）, Straw ＋ N（ CRN ） ,Manure（MO） ,Manure ＋ N（MN）,Manure ＋ N ＋ K（MNK） ,Manure ＋ N ＋ P（MNP） ,Manure ＋ P ＋ K （ MPK ）, Manure ＋ N ＋ P ＋ K （ MNPK）, and Manure ＋ Straw ＋ N （ MRN ）. Compared with no P treatments, all P treatments showed significant increase in total P （ TP）, Olsen P （Olsen-P） and inorganic P （I-P） in the plow layer （ 0-15 cm） and only MNp, Mpx, MNpx and Cpx did in organic P （O-P）. Significant TP accumulation in MNPK and Olsen P in MNPK and CNP were found at the depth of 30 cm in soil profile, and I-P in MNPK, MNP, MRN and MN at the depth of 25 cm. P accumulation in the plow layer and P downward transport in the soil profile were related to application rate, fertilization pattern （ fertilizer P,manure P,single fertilizer application and mixed fertilizer application） and form of P. I-P plays a very important part in P downward transport in the profile and I-P from manure went deeper than that from fertilizer. The treatments varied in P pollution risk to water body,with MNPK being the highest. The risk is higher to surface water than to groundwater,in the rice season than in the wheat season, and in years with excessive rainfall than in those with normal rainfall.