Aplication of DRIS on Applying Fertilizer to Citrus

From 1991 to 1993, contents of N、P、K, Ca and Mg in the leaves of spring shoots in xue-gan and Fuju were analysed, and the index of DRIS (Diagnosis and Recommendation Integrated Sys-tem) was determinated. The equilibrium of such elements was investigated.The index showed that the orchard in hilly land was deficient in Ca and Mg. Effects of applying Ca and Mg ferilizer on thc contents of nutrition elements in the leaf.yield and fruit character were also investigated.