For rice, few studies use foliar analysis methods developed for local conditions of climate, soil or cultivars. The purpose of this study was to evaluate the methods of Compositional Nutrient Diagnosis and of Mathematical Chance to define nutritional standards for rice fields in Rio Grande do Sul state, Brazil. Data of 356 irrigated rice fields for grain yield and foliar contents (N, P, K, Ca, Mg, S, B, Cu, Fe, Mn, Zn, and Mo) were used to calculate the sufficiency ranges by the Mathematical Chance method. The sufficiency ranges were compared with critical values proposed in the literature and with the confidence interval of the average nutrient contents of nutritionally balanced crops identified by the Compositional Nutrient Diagnosis method. There was little agreement between the sufficiency ranges indicated by the methods of Mathematical Chance and Compositional Nutrient Diagnosis and the respective values in the literature. The appropriate range of foliar contents, consistent with highest average yield of rice fields, was 23-28 g kg-1 for N; 11-14 g kg-1 for K; 1.4-2.0 g kg-1 for S; 6-12 mg kg-1 for B; and 70-200 mg kg-1 for Fe. For the contents of P, Ca, Mg, B, Cu, Mn, Zn, and Mo none of the tested ranges allowed to discriminate rice yield.
Oriza sativa L.; critical level; sufficiency range; foliar diagnosis; DRIS
