Soil Solute (phosphorus) To The Root Of Migration And Absorption Mechanism Model Of Applied Research

This paper dealt with some application field of mechanistic model of nutrient transport and uptake of P (Claassen et 1986, C model) by cotton and rice under different conditions of fertilizer application , by combing the pot with field trial and traditional statistic analysis with compute simulation .The effect of N , P and K to root growth of cotton and rice was studied ,and showed that P could improve the root growth of cotton and rice ,but excessive P might hinder the root growth of cotton , and K could approve the root growth of rice also ,and excessive N might impede the root growth of rice clearly.This paper studied the application of mechanistic model on cotton and rice under the field condition for the first time .The results showed that the C model could simulate the P absorption of cotton and rice fairly. But under the P-deficient and P-excessive situations, the error was obvious, N-rates applied affected the result of simulation, and K-rates did not. So the effect of other fertility factor and P-stressed and excessive-p situation on P absorption should be studied in the future. This study predicted the P application and the most efficiency added-p volume of soil on cotton by using C model and tested this method. Result showed the method was feasible, although under the P-deficient and P-excessive conditions there was higher error in predicting P-absorption rates , and we could omit the error when predicting the P-application and the most efficiency added -P volume soil on cotton . This paper studied the relationship of different parameters by using multi-dimensional sensitivity analysis, and the sensitivity of parameter on cotton and rice in different fertilizer application conditions. The study showed that the difference is large, between cotton and rice p absorption on parameter sensitivity. Under different added-p rates, the sensitivity of parameters on cotton andrice was quite different. Under p-stressed condition, Most of the parameters were sensitive to P absorption, and the sensitivity of parameters changed if changing the P-application. Different N and K levels could influence the P-uptake by rice and did not influence the sensitivity of parameters. So the mechanistic model should consider the parameter about other nutrient factors. The result of multi-dimensional sensitivity analysis showed that the sensitivity of parameters was dependent on each other. In general soil conditions, Cli and R0 and Imax were most sensitive to P-uptake , and the V0 always was not , but it was sensitive if the V0 became bigger; the sensitivity of De depend on the value Cli and Imax, The parameter Cli, R0,Imax,V0,De was dependant on each other.