Exportação de nutrientes em fruto de cupuaçu (Theobroma grandiflorum (willd. ex spreng.) Schum.) em três solos da Amazônia Central

Abstract

The farmers that grow cupuaçu (Theobroma grandiflorum (Willdenow ex Sprengel) Schumann, Sterculiaceae) recognize the importance of fertilization to increase productivity, but little research has been done to identity an agronomically correct and economically viable, scheme. The present study evaluated the from exportation of nutrients by the cupuaçu fruit three soils (Yellow Oxisol - LA [President Figueiredo - AM], Indian Dark Earth - TPI [Iranduba - AM] and flood plain [Manacapuru - AM]). In each farm, 20 plants were sampled, and soil, leaves and fruits were collected between March May 2004, the harvest season in the region. The fruits collected from the flood plain were heaviest (1.64 kg), followed by TPI (1.34 kg) and LA (1.24 kg). The highest concentrations of potassium in the soil (288.7 mg.dm3) and in the leaf (1.54 g.kg-1) were found in the flood plain, followed by TPI (133.8 mg.dm3 and 1.22 g.kg-1) and LA (3.0 mg.dm3 and 0.73 g.kg-1). The highest concentration of nutrients was observed in the seed (N, P, Ca, Mg and Zn), pod (Fe and Mn) and pulp (K). The export of macronutrients by the cupuaçu fruit obeyed the following orders: Flood plain K (6.61 g.fruit-1) > N (5.97 g.fruit-1) > Mg (1.05 g.fruit-1) > P (0.83 g.fruit-1) > Ca (0.80 g.fruit-1) and Fe (43.45 mg.fruit-1) > Mn (20.04 mg.fruit-1) > Zn (18.40 mg.fruit-1); TPI N (5.03 g.fruit-1) > K (4.13 g.fruit-1) > Ca (1.06 g.fruit-1) > Mg (0.98 g.fruit-1) > P (0.84 g.fruit-1) and Fe (43.42 mg.fruit-1) > Zn (21.87 mg.fruit-1) > Mn (17.09 mg.fruit-1); LA N (4.68 g.fruit-1) > K (4.17 g.fruit-1) > Mg (0.70 g.fruit-1) > Ca (0.67 g.fruit-1) > P (0.38 g.fruit-1) and Fe (32.68 mg.fruit-1) > Mn (19.43 mg.fruit-1) > Zn (14.45 mg.fruit-1). The highest potassium export was from the flood plain s soil, permited by the greater fertility of that soil. The potassium exported from TPI was 23.5% less than the flood plain and the LA was 16.6 % less.