Study On Phosphorus Status And Availability In Different Years Of Vegetable Green House Developed From Black Soils

This research investigates phosphorus accumulation and changing trend in the soils for different planting years and depth in the area of Harbin's vegetable green house developed from black soils .The main results are as follows:The contents of phosphorus, such as in the forms of total phosphorus, available phosphorus, organic phosphorus,Ca₂-P,Ca₈-P, Ca₁₀-P,Al-P,Fe-P,O-Petc,are in a massive accumulation in Harbin vegetable green house soil in 0⁶0 cm layer, and are higher than the neighboring vegetable soil. These forms of phosphorus are in the highest content at the 0²0cm soil layer,and reduces along with the increasing of soil layer depth .The content of inorganic phosphorus in vegetable green house soil was in the order of Ca-P(Ca₈-P>Ca₂-P>Ca₁₀-P)>Al-P>Fe-P>O-P.Various forms of accumulation of phosphorus of twenty-five years in A Cheng area achieve the maximum value.and at all soil layers the content of all forms of phosphorus is in periodical variation along with the grow years. The contents of phosphorus are always be decreasing followed with increasing after the treatment of different types and quantities of fertilizer and crop rotation. In Dao Li area ,the content of phosphorus are increasing with the planting years and reaches the maximum value in the eighteen years of the soil.After reaching the maximum value,the content of phosphorus shows a trend of decreasing along with the grow years in the area of A Cheng and Dao Li, and the total phosphorus, available phosphorus and organic phosphorus rich layers shift deeply. Comparison of phosphorus components in A Cheng and Dao Li shows that the contents of organic phosphorus and inorganic phosphorus are increasing simultaneously after fertilizering.and the rate of inorganic phosphorus are decreasing with the depth in both of A Cheng and Dao Li. The inorganic phosphorus is more accumulated than organic phosphorus in the 0-60cm soil layer and there is a dynamic balance between them,The rates of inorganic phosphorus and organic phosphorus are not much different between the vegetable green house and the neighboring nature soilThere is a linear relationship between Olsen-P and other kinds of inorganic phosphorus,the relationship rate show as , Ca₂-P is 0.9696**, Ca₈-P is 0.8157**,Ca₁₀-P is 0.6593**, Al-P is 0.8453**, Fe-P is 0.7792**, O-P is 0.5937**.The research reveals that effective phosphorus play a important role in inorganic phosphorus accumulation.Along with depth the content of low states Al-P decreased and the insoluble Ca₁₀-P increased.The investigation datas show that long term over–fertilizered had resulted in the ultra accumulation,and so there should be a control ,and fertilizer m oderation should be advocated.Oxalic acid, humic acids and biological agent can increase the content of effective phosphorus,and the activated capacity is in the turns of oxalic acid>humic acids> biological agent. Add 10g oxalic acid in addition the processing period of each culture were associated with other treatments was significant. This indicated that addition of 10g oxalic acid can get the best activation.For Ca-P dominanted calcareous black soil, oxalic acid can activated both Ca₂-P/Ca₈-P and some low low activated phosphorus such as Al-P,Fe-P and Ca₁₀-P,the content of inorganic phosphorus are detected increased in all soil samples with treatments and the increasing agree is Al-P>Ca₈-P >Fe-P >Ca₂-P>Ca₁₀-P>O-P. The biological agent can also accelerate the insoluble, slow inorganic phosphorus transform to effective phosphorus , and more quantity more effective.