NUTRITIONAL DIAGNOSIS OF COFFEE PLANTATIONS IN THE UPPER JEQUITINHONHA VALLEY, MINAS GERAIS STATE, BRAZIL: DRIS NORMS AND CRITICAL NUTRIENT RANGES

In the Diagnosis and Recommendation Integrated System (DRIS), norms for coffee in the Upper Jequitinhonha Valley, Minas Gerais, Brazil, have not been established yet. The lack of these norms hinders the application of the DRIS to the coffee plantations in the region. The foliar diagnosis, based on the DRIS and on critical reference ranges, stands out among the tools that allow an efficient use of fertilizers. This study aimed to determine DRIS norms as well as to establish values of the critical nutrient ranges of reference for the nutritional diagnosis of coffee in the Upper Jequitinhonha Valley, by the DRIS. The foliar concentrations of N, P, K, Ca, Mg, S, B, Cu, Fe, Mn, and Zn in 52 coffee plantations were determined in two cropping years (2005 and 2006). To establish DRIS norms 23 plantations were chosen, with yields higher than or equal to 30 sacks of coffee grain per hectare in each harvest. The critical nutrient ranges for the DRIS were obtaind by determinig the frequency with which each nutrient content of the plantations in two harvests was deficient, adequate or excessive according to the cited standards and sufficiency ranges reported in the literature. The DRIS norms were established for coffee in the region of the Upper Jequitinhonha Valley and used to propose appropriate critical ranges. For this purpose, the following values were proposed: for N (2.25-2.79 kg dag(-1)), P(0.18-0.22 kg dag(-1)), K(1.72-2.10 kg day(-1)), Ca(1.26-1.51 kg dag(-1)), Mg(0.29-0.35 kg day(-1)), S(0.13-0.32 kg day(-1)), B(83.8-96.3 mg kg(-1)), Cu(5.7-9.3 mg kg(-1)), Fe (67.5 - 116.2 mg kg(-1)), Mn (219-422 mg kg(-1)), and for Zn (17.4-30.0 mg kg(-1)). In regional coffee plantations with inadequate nutrition deficiencies of P, K, S, B, Cu, Mn, and Zn were observed as well as excessive contents of Ca, Mg and Fe.