Effects of nitrogen and phosphorus in cotton in the state of Sergipe, Brazil

Abstract

Two 4² factorial experiments were conducted to study the effects of four levels of nitrogen (0, 40, 80 and 120 Kg/ha of N) and phosphorus (0, 80, 160 and 240 Kg/ha of P₂O₅) in cotton, variety IAC 13-1, in the counties of Poço Verde and N.S. da Glória, State of Sergipe, Brazil, in 1973. The analysis of initial and final stands has shown that, in Poço Verde, the nitrogen has damaged the stand. Nitrogen increased production up to the dosage of 120 Kg/ha of N, in both places, and only this level was superior to the control. In relation to phosphorus, in N.S. da Glória production increases of 160 %(605,6 Kg/ha) and 264% (1.002,6 Kg/ha) over the control were observed, by the application of 80 and 160 Kg/ha of P₂O₅, respectively. The analysis of the profit: cost relation in the experiment conducted in N.S. da Glória has shown that the treatments N₀01, N₃P₁, N₂P₂ and N₁P₁ have returns of 84 %, 80 %, 62 % and 59 % respectively. Nitrogen fertilizer had influence on capsule weight, seed weight, fiber index and fiber length in N.S. da Glória, and on fineness in Poço Verde.