Greenhouse Paddy-upland Rotation Affects The Form And Availability Of Soil Phosphorus

Nowadays greenhouse cultivation is becoming one of the significant cultivation models in China,which plays a vital role in planting vegetables and supplying off-season crops. Moreover, China hastaken possession of the largest greenhouse cultivation area in the world, which makes China becomethe one of these countries which hold greenhouse cultivation technology.However, with suffering from high temperature, humidity condition and high fertilizer inconsecutive years, it has given rise to a lot of problems. For instance, accumulated lots of nutrientcomponents in soil and unbalanced nutrient will lead to soil acidification and secondary salinization andso on.Phosphorus is the essential nutrition in crops growing, however, the accumulated phosphorusnutrition in greenhouse soil will not only take an effect on availability of phosphorus，but also it makeseasier to enter water resource when Jie membrane washing in the summer, causing water eutrophicationproblems, serious impact on the ecological environment.Phosphorus, being one of the essential nutrition in crops growth, is the one of key factorswhich cause soil acidification and secondary salinization. Nevertheless，being driven from high profit ofgreenhouse cultivation, farmers are still fertilizing much more phosphorus in planting crops, whichdefinitely causes that the accumulated nutrition in soil is becoming more serious. During the pastseveral years, field-upland field rotation in greenhouse cultivation is increasingly playing a significantrole in balancing nutrition in soil and releasing soil acidification and secondary salinization. But there isstill something to consider, field-upland field’s rotation, removal and influence in greenhouse cultivationremains uncertain, which will take an effect on fertilizing properly and promoting in some way.This article is based on three farming modes, rice-eggplant rotation in greenhouse, greenhouseeggplant dry film uncovering leaching and wheat-rice rotation in detail, which has been continued formore than two decades in Zhicheng, Changxing County, Zhejiang province.Moreover, it is supposed toresearch on changes of soil total phosphorus, rapidly available phosphorus, inorganic phosphorusclassification, phosphorus adsorption and desorption and so on, providing a foundation for the ricefield-upland field rotation theory. According to the research on this theory, the conclusions arefollowed. （1）among the three farming modes of rice-eggplant rotation, greenhouse dry farming andwheat-rice rotation, total phosphorus, rapidly available phosphorus, Ca-P, Al-P, Ca-P, O-P in the soilsection plane are decreasing as the deepening of soil, phosphorus accumulates in the soil layer of0²0cm because of fertilization rate and other reasons. The changes of total phosphorus content aremainly because of the hierarchal relationships among the three farming modes are rice-eggplant rotationin greenhouse> greenhouse dry farming> wheat-rice rotation.（2）inorganic phosphorus fractions significantly under different rotation systems, and inorganicphosphorus content in soil decreased with soil depth. In Al-P and Fe-P in greenhouse soil surfaceenrichment in forms, contents are398.72mg·kg^-1and380.46mg·kg^-1. The Al-P content of GreenhouseEggplant and rice rotation for275.67mg·kg^-1is significantly lower than that of greenhouse cultivation,while Ca-P is higher than those of the dry, showing that the rotation system in alternate wetting anddrying decreases the content of Al-P in soil and increases the content of Ca-P. Because of lessfertilization of wheat and rice rotation amount, phosphorus contents are low.（3）paddy-upland rotation takes an awful effect on phosphorus adsorption and desorption, themaximum P adsorption capacity of soil （Xm） size relationship: wheat and rice rotation (526.32mg·kg^-1)> greenhouse cultivation (434.78mg·kg^-1)> Greenhouse Eggplant and rice rotation (384.62mg·kg^-1). The relationship between the adsorption equilibrium constant K size of three different tillageas: greenhouse cultivation （0.154）> wheat and rice rotation （0.082）> Greenhouse Eggplant and ricerotation （0.071）. The relationship between maximum buffering capacity of soil size as: greenhouse dry（67.11）> rice-wheat rotation （43.29）> Greenhouse Eggplant and rice rotation （27.25）. With therelationship between exogenous phosphorus concentration increased soil Greenhouse Eggplant and ricerotation and rice-wheat rotation on phosphorus adsorption and desorption amount with the linearequation, no linear relationship between adsorption and desorption in dryland.