Absorção de nutrientes pela cultura do feijoeiro

Foi determinada a marcha de absorção dos macronutrientes essenciais pela cultura do feijoeiro (Phaseolus vulgaris L.) em casa de vegetação. O máximo de crescimento foi atingido ao completar a planta 50 dias de idade. Os elementos N, K e Ca foram absorvidos até aos 50 dias da germinação. O Mg e S, até aos 70 e 60 dias, respectivamente. O fósforo foi absorvido durante todo o ciclo. Uma população correspondentemente a um hectare absorveria 201,2 kg de N, 17,5 kg de P, 200,7 kg de K, 116 kg de Ca, 36 kg de Mg e 36 kg de S. Para uma produção de 500 kg de grãos, a exportação de nutrientes seria de 14,3 kg de N, 1,1 kg de P, 10,2 kg de K, 1,8 kg de Ca, 1,0 kg de Mg e 2,2 kg de S. The purpose of this investigation was to gain information on the rate of fresh and dry matter production and nutrient absorption by bean plants (Phaseolus vulgarisL.). The test was carried out in the greenhouse in Mitscherlich pots containing fertilized soil. Every ten days plants were harvested divided into roots, stems, leaves, and fruits and analysed for N, P, K, Ca, Mg and S. Data obtained allowed for the following main conclusions: a) the initial rate of growth of the bean plant during the first 30 days is rather slow. The maximum growth occurred when the plant was 50 days old. b) the maximum absorption rate according to the element was: N, K and Ca, at 50 days; Mg and S at 70 and 60 days respectively. Phosphorus was absorbed by the crops from the beginning up to the end of the cycle. c) The following amounts of element in kg/ha were absorbed by the plants: Element Entire plant In 500kg of Grains kg kg N 201.2 14.3 P 17.5 1.6 K 200.7 10.2 Ca 116.0 1.8 Mg 36.0 1.0 S 36.0 2.2