Walnut - Wheat Intercropping System Of Nitrogen, Phosphorus Cycle In The Law

Walnut is one of important economic trees in Wei bei, Shaanxi and its developing speed is faster than others, but its production cycle is longer and the investment in earlier stage is greater. How to enlarge the effective utilization of soil and raise quickly the output value becomes more and more important. It is testified in practice that compound management of walnut and crops is a effective way in improving the utilization ratio of soil, supporting long-term with short-term and replacing fostering with cultivation. At present, the study of fruit trees and farm inter-cropping mainly concentrates on dividing types, the quantitative observation and the assessment of ecological and economic efficiency and the utilization and management of resources and so on. These studies are short of the systematic research of nutrient cycle under compound system. So author studies the N P nutrient cycle under inter-cropping compound system of walnut at age 4 and wheat in order to provide scientific evidence for the N. P management of inter-cropping compound system. The results as follows: 1. Measuring comprehensively the variation of N P content of soil under compound system. The results prove that the wheat inter-cropping can't change the soil抯 N and P vertical distribution, but under compound system is has an important effect on the horizontal distribution of N~ P content and it appears greater N~ P consume in the distance 0.5m from crown. Especially in the 20-40m soil layer, walnut and wheat contend intensively with fertilizer and the N P consume is greater, but the distance exceeds 0.5m from crown, the N P content in soil inclines to rise again. Compared with the noninter-cropping soil the compound system can effectively improve the N P content in 0-20cm soil layer. 2. According to the characteristic of compound management, we put forward a formula of N P biological cycle under compound system: absorb storage +return +lose. The computed results according to it, the N P absorption content under compound system are 70.924kg/bin2 and 19.425 2 kg/bin respectively every year, and they are 32.25 times and 27.26 times of noninter-cropping soil respectively, the absorption content is greater; the returning content is only 19.116% and 17.996% of the N * P absorption content, so it is important to improve the productivity of compound system by intensifying the N~ P management of compound system. The cycle results prove that the N~ P net output rate of soil under compound system is 55.492kg/bin2 and 16.044kg/bin2 respectively and can be regarded as the fertilizing index every year. 3. Obtaining the N. P dynamic equations of every network section under compound system: N cycle equations: P cycle equations: = 0.4877x3 ?0.0238x1 -~- 2.213 = 0. 4493x3 ?. 0076x1 + 0.598 dt dt = 0.0238x ?6522 ~- ?0.00763x1 ? 0883x ?1.47 dt . x,?.1612 dt 2 ___ = 0.6522x2 ?0.4877x3 ?0 dt dt ?.2883x, ?.4493x3 4. According to the characteristic of walnut and wheat under compound management, we select the efficiency of nutrient utilization, the coefficient of nutrient and the turnover period of nutrient as indexes. The results prove that the biological cycle of inter-cropping compound system can more highly utilize N. P nutrient than that of noninter-cropping soil, and has the characteristic of stronger accumulation and faster turnover, but the N~ P absorption coefficient of compound system is higher than that of noninter-...