长期定位施肥对潮土磷素形态和有效性的影响

Effect of Long-term Fertilization on Phosphorus Fraction and Availability in Fluvo-Aquic Soil

研究长期定位施肥对潮土各形态磷含量变化及磷有效性的影响,为潮土合理施用磷肥提供理论依据。长期定位施肥试验开始于1990年,设CK (不施肥)、N2 (单施尿素)、N2P (不施钾肥)、N2K (不施磷肥)、N1PK (低量氮肥和磷钾肥)、N2PK (平衡施肥)、N3PK (中高量施肥)、N4PK (高量氮肥和磷钾肥)、N2PKM (化肥和有机肥)、N2PKS (化肥和玉米秸秆还田)10个处理;采用Tiessen-Moir磷素分级法测定各施肥处理土壤不同形态磷含量,用常规方法测定有效磷、全磷含量,分析不同形态磷含量间的相关性。结果表明:经过28年定位施肥处理,N2PKM处理土壤各形态磷含量为盐酸态磷(HCl-P)>残留态磷(Residual-P)>氢氧化钠无机磷(NaOH-Pi)>氢氧化钠有机磷(NaOH-Po)>碳酸氢钠无机磷(NaHCO3-Pi)>水溶性磷(Resin-Pi)>碳酸氢钠有机磷(NaHCO3-Po)。在各施肥处理间,N2P、N1PK、N2PK、N3PK、N4PK、N2PKM、N2PKS处理土壤Resin-Pi、NaHCO3-Pi和NaOH-Pi含量显著高于CK、N2、N2K处理,而处理间NaHCO3-Po、NaOH-Po、HCl-P和Residual-P含量差异不显著。除NaOH-Po外,其它形态磷含量与供试土壤有效磷、全磷含量呈极显著相关,其中Resin-Pi对有效磷贡献最大,说明Resin-Pi是最有效的磷源。供试土壤条件下,合理配施化肥有机肥,可以激发磷素后效,使积累磷素向有效态转化,施用有机肥料能显著提高土壤中各磷组分含量,其中有机无机配施处理(N2PKM)提高程度高于单施化肥(N2PK),施用秸秆处理的各磷组分含量同样显著高于不施肥和化肥处理,且施用有机肥和秸秆处理(N2PKS)的中活性和中等活性磷均与土壤速效磷、全磷呈显著正相关,可在潮土上施用有机肥或秸秆处理,从而保持高比例的土壤有效磷库。

The changes of various fractions of phosphorus(P) separated with Tiessen-Moir method and its availability under long-term fertilization were investigated,in order to provide a theoretical basis for the reasonable application of P fertilizers in the Fluvo-aquic soil.Different fertilization treatments included no fertilization(control,CK),single application of urea(N2),no potassium(K) fertilizer(N2P);no P fertilizer(N2K),low amount of nitrogen(N) fertilizer combined with P and K fertilizers(N1PK),balanced fertilization(N2PK),medium or high amount of fertilizers(N3PK),high amount of N fertilizer combined with P and K fertilizers(N4PK),chemical combined with organic fertilizers(N2PKM),chemical fertilizers combined with corn straw returning(N2PKS).The correlation between soil P and available P and total P were analyzed.After 28 years of different fertilization treatments,the P fraction contents in the N2PKM treatment were decreased in the order of hydrochloric acid extractable P(HCl-P)> residual P(Residual-P)>sodium hydroxide extractable inorganic P(NaOH-Pi)> sodium hydroxide extractable organic P(NaOH-Po)> sodium bicarbonate extractable inorganic P(NaHCO3-Pi)> Water-soluble P(Resin-Pi)> sodium bicarbonate extractable organic P(NaHCO3-Po).Compared with CK,N2,and N2K treatments,N2P,N1PK,N2PK,N3PK,N4PK,N2PKM and N2PKS treatments significantly increased the contents of Resin-Pi,NaHCO3-Pi and NaOH-Pi,while the contents of NaHCO3-Po,NaOH-Po,HCl-P and Residual-P were not significant among different treatments.Except for NaOH-Po,the correlations among the contents of the other P fractions,available P and total P in the soil were significant.The contribution of Resin-Pi to available P was the most,indicating that Resin-Pi was the most effective source of P.The application of organic fertilizers significantly increased the contents of various P fractions in the soil,especially in the N2PKM compared with N2PK treatments.The contents of various P fractions in the N2PKS treatment were also significantly higher than those in the chemical fertilizer application treatments.The contents of soil medium and medium active P were significantly correlated with those of available P and total P in the organic fertilizer and straw treatments(N2PKS).Organic fertilizer or straw could be applied to fluvo-aquic soil to maintain a high percentage of soil available P pool.