Produtividade do algodoeiro adensado em segunda safra em resposta à adubação nitrogenada e potássica 1 O nitrogênio e o potássio são os nutrientes mais requeridos pelo algodoeiro. O algodão, cultivado em segunda safra, após a colheita da soja, tem sido uma opção dentro dos sistemas de produção do cerrado brasileiro. Este trabalho objetivou avaliar o efeito das adubações nitrogenada e potássica sobre o estado nutricional, os componentes de produção e a produtividade do algodoeiro, cultivado em sistema adensado, semeado em segunda safra. O experimento foi conduzido após a colheita da soja e em delineamento de blocos ao acaso com quatro repetições.
Yield of cotton as a second crop in narrow planting in response to nitrogen and potassium fertilizationNitrogen and potassium are the most required nutrients for cotton crop. Cotton grown as a second crop, after soybean harvesting, has been an option for crop system in the Brazilian savanna. This study aimed to evaluate the effect of N and K fertilization on the nutritional status and the yield components of cotton grown as a second crop, after soybean, and in a narrow planting system. The experiment was carried out adopting a completely randomized block experimental design. The treatments were set up in a 4 × 4 factorial arrangement with four replications. Factor A was the four N doses (0, 50, 100, and 200 kg ha -1 ) and factor B was four K 2 O doses (0, 40, 80, and 160 kg ha -1 ), applied as side-dressing. The N and Mg concentration levels in the leaf increased linearly with the N doses, while the concentration levels of S and Fe decreased (quadratic effect). The K 2 O doses resulted in positive and negative effects on K and Mg, respectively, in the leaf. The N fertilization promoted higher lint yield response when compared with K fertilization, as lint yield rate per kg of N was twice the yield rate per kg of K 2 O. The highest lint yields were reached with 148 kg ha -1 and 107 kg ha -1 of N and K 2 O, respectively.