Irrigation, nitrogen and potassium levels under subsurface drip on sugarcane

Abstract

The objective of this work was to define the optimal irrigation, nitrogen and potassium levels in sugarcane, cultivar RB867515, applied by subsurface drip, in the first ratoon, to maximize stem, sugar and alcohol yield. The experiment was carried out on Plinthaquox soil in the county Uniao, Piaui State, Brazil, during the 2008/2009 agricultural season. The treatments consisted of: irrigation levels including rainfall (W1, 767.5; W2, 898.5; W3, 971.0; W4, 1,053.0; and W5, 1,154.0 mm) and nitrogen and potassium levels (N1, 44.0; N2, 78.0; N3, 111.0; N4, 144.0; N5, 178.0; K1, 44.0; K2, 67.0; K3, 89.0; K4, 111.0; and K5, 133.0 kg ha(-1)). The experimental design used was a randomized complete block with two replicates, in a 5x5x5 (W x N x K) 1/5 fractional factorial arrangement. Maximum stem yield (207.4 Mg ha(-1)) is reached with 1,154.0 mm of water associated with 114.2 kg ha(-1) of N and 60.1 kg ha(-1) of K2O. Maximum sugar (25.3 Mg ha(-1)) and alcohol (20.0 m(3) ha(-1)) yield is achieved with 1,154.0 mm associated with levels of 90.0 kg ha(-1) of N and 60.0 kg ha(-1) of K2O.