Properties Of Phosphorus Adsorption And Desorption In Main Forest Soils In Southern China

This research was made on the properties of phosphorus adsorption and desorption in main forest soils in southern China. The main results showed that:1. Rhizosphere is the environment that roots directly confronted, which is quite different from the common soil because of the interference of roots, so tree roots had the effect of inhibition on phosphorus immobilization to a certain extent. Amount of absorbed phosphorus was different in soils with phosphorus added into soil changed. Amount and ratio of absorbed phosphorus in different soils were different under the same amount of phosphorus added. Properties of absorbed phosphorus in different soil layers were different, the amount of absorbed phosphorus in subsoil was higher than that in topsoil generally. Phosphorus absorbed and immobilized in rhizosphere was less than that of in root zone and unroot zone.2.The isothermal adsorption curve of each can be partition into two parts. Phosphorus adsorption amount and phosphorus consistency slope in equilibrium solution are relatively higher than the slope of phosphorus adsorption amount and phosphorus consistency when fertilizer amount added increasing continuously. Langmuir equation was mostly tally with experiment data. This showed that Langmuir equation could be used as a token for phosphate isothermal adsorption properties.3.Regression analysis revealed that phosphorus adsorption maxima, standard phosphorus requirements and combining energy had a positive relationship with the amount of clay particle and hygroscopic water of soils and they had no relationship with the pH value, while having a negative relationship with the contents of organic matter, available phosphate and total phosphate of soils.4.Phosphorus desorption function was stronger than adsorption function in phosphate dynamic equilibration. Phosphorus X. and desorbed phosphorus had mighty notability reverse correlation. The inhibition of organic acid was different. Between them humic acid had the stronger effect of inhibition on phosphorus immobilization than citric acid. When humic acid and citric acid were added into soils at 2.0 g kg-1 and 4.0 g kg-1 separately ,they could inhibit much of phosphorus from immobilization.5.Regression analysis showed that phosphorus added into soils had significant linear relationship with phosphorus consistency and each coefficient had overrun 0.98 in soil's equilibrium solution. A little phosphorus fertilizer is required in soilsthen forest can have normal growth. Phosphorus amount in each soil is middling or less than need, which is ultimately enough for forest grow in gear quickly.