Application DRIS on winter wheat fertilization in Guanzhong area

There are many plant nutrient diagnosis methods, such as comparative curve method, polygonal graphic method, and critical value method and so on. However, those diagnosis methods have certain limitation and can not (response) to the inner link among different kinds of nutrient elements and interrelation between external environmental (factors). Diagnosis and Recommendation Integrated System (DRIS) can overcome these shortcomings to some extent. Its main scientific basis is: collecting crop yield and leave ingredient data of a certain crop in a certain area for the determination of standard values for DRIS N,P,K. Analysis results of unknown sample were evaluated according to these standard values. The advantage of DRIS is that it can determinate crops nutritive elements demanding order, furthermore, (determination) is not confined by the plant-age and leaves-place of the crop. DRIS has been extensively applied in the (United) States, South Africa, Netherlands, Australia and Brazil. Combining field investigation and plot trials (including long-term located experiment) with laboratory chemistry analysis, the expression calculation of analysis data of N, P and K in wheat leaves of low yield group (yield 6000 kg/hm2)and high yield group(yield6000 kg/hm2) were done according to DRIS. Nutrient content ratio in wheat leaves were (selected) as diagnosis parameters. A sample unit was set up for the verification of the adaptability of DRIS and further (extension). The results showed that DRIS was suited to the nutrient diagnosis of N, P and K for winter wheat in western part of Guanzhong area while the ratio of N, P and K of high yield crop was selected as diagnosis parameters. The diagnosis of DRIS could point out the demanding order and level of nutrient elements. Furthermore, the diagnosis was not confined by plant-age and leaves-place.