THE NUTRIENT INPUTS, OUTPUTS AND BALANCE OF PAULOWNIA CROP INTERCROPPING SYSTEM
农桐复合系统营养元素的输入、输出与平衡分析

Analytical results of nutrient inputs, outputs and balance of Paulownia -crop intercropping system revealed that the annual uptake of N, P, and K in current Paulownia -crop intercropping system are 276.2 kg, 92.1 kg, and 172.2 kg per hectare respectively, and the annual inputs of N, P, and K are 370.1 kg, 181.5 kg, and 113.5 kg accordingly; the ratios of inputs to outputs are 1.34 for N, 1.97 for P, and 0.66 for K, indicating a positive balance of N and P in the system whereas negative for K; the inputs of organic nutrients are relative low, for the input of organic N is only 68% that of the inorganic N and the input of organic P is only 21% that of inorganic P; the input ratio of N, P and K is inharmonious, for the nutrient inputs are N: P: K = 1: 0.49: 0.31 while the nutrient uptakes of trees and crops are N: P: K = 1: 0.33: 0.62. The input of P is relative high while K is relative low than what it should be.