长期施肥对菜地土壤磷素积累的影响

摘要

以温室、大棚和菜粮轮作3种不同类型菜地土壤为材料,研究了菜地土壤全磷、有机磷、有效磷、无机磷组分含量变化及其土体分布特征.结果表明,菜地土壤磷素积累量大、积累速度快,10年左右的温室菜地和大棚菜地土耕层全磷含量增加1 000 mg/kg左右,积累速度约100 mg/kg年,菜粮轮作土壤磷素积累数量相对较少.菜地土壤积累的磷主要是无机磷,0～20 cm土层中无机磷含量占土壤磷素总量的90％以上,菜地土壤有机磷积累数量较少,其含量为130～170 mg/kg.菜地土壤磷素主要分布于0～ 20 cm耕作层中,其含量一般为0～ 80 cm土体磷素总量的50％.与母质土壤相比,菜地土壤中下部土层也有磷素积累现象,种菜时间越长,其积累量越多,特别是有机磷在菜地土壤中有较明显的淋溶特征.菜地土壤无机磷组分与母质土壤相比变化很大,而且不同类型菜地土壤无机磷组分变化不同,潮菜地土无机磷组分以Ca8-P、Ca10-P、Ca2-P和O-P为主,与母质土壤相比,Ca8-P、Ca2-P和Al-P含量增加较多,Ca10-P含量仅有微量增加.黑姜菜地土无机磷组分以Al-P、O-P、Ca8-P、Ca2-P为主,与母质土壤相比,含量均增加较多.菜粮轮作土壤无机磷组分以Fe-P和O-P为主,与母质土壤相比,Fe-P含量增加较多.菜地土壤Ca2-P和Ca8-P绝大部分积累于耕作层,占0 ～ 80 cm土体中Ca2-P和Ca8-P总量的70％ ～ 80％.菜地土壤有效磷含量普遍较高,10年左右的典型菜地耕作层土壤有效磷含量为200 mg/kg左右.%This paper reported the content of total phosphorus( P) ,organic P,available P,and inorganic phosphorus ( Pi) fractions in three type of vegetable soils. The results showed that the total P content in 10-year greenhouse vegetable soils was 1 000 mg/kg higher than that of cereal crop soils. The accumulation rate of total P was nearly 100 mg/kg per year,and the content of P accumulation in the vegetable-crop rotation soils was lower. The main P form accumulated in the vegetable soils was Pi, which was above 90% of the total P, while organic P content was 30-170 mg/kg. Most of the P accumulated in vegetable soils was distributed in plough layer (0 -20 cm in depth) . But compared with the cereal crop soils, P accumulation was observed in middle and subsoil in vegetable soils. It is especially that organic phosphorus showed relatively serious leaching characteristics. Different types of vegetable soils changed differently in Pi fractions. Pi in alluvial vegetable soil was mainly Ca-P and O-P,and the contents of Ca8-P,Ca2-P, Al-P increased much more and Ca10-P increased slightly. Pi content in black clay vegetable soil was mainly Al-P, O-P, Ca8-P, and Ca2-P, while content of Al-P, O-P, Ca8-P and Ca2-P increased much more. Pi content in vegetable-crop rotation soils was mainly the form of Fe-P and O-P, while content of Fe-P increased much more. Most of Ca2-P and Ca8-P accumulated in plough layer soil,and 70% of the total amount of the Pi fractions accumulated in 0 - 80 cm in depth in soil profile. Available P( AP) content in typical old vegetable soils was about 200 mg/kg .