Efecto de distintas alternativas de fertilización fosfatada en la secuencia trigo - soja sobre el fósforo asimilable y los rendimientos en la provincia de Tucumán, Argentina

ten phosphorus fertilization alternatives were evaluated in a soybean-wheat cropping system in la ramada de arriba (burruyacú, tucumán province). the study was carried out on a typic argiudoll, with 3.5% organic matter and 7.8 ppm phosphorus (p-bray 1). the objective of this trial was to estimate the effect of each fertilization alternative on available phosphorus concentration in two soil layers, 0-5 cm and 5-25 cm, over five years (from 2002 to 2007), and on soybean and wheat yields. evaluated treatments consisted in applying 30, 45 and 60 kg p2o5/ha as triple superphosphate yearly only to soybean, only to wheat and to both crops. p residual effect was found for both crops when 45 kg p2o5/ha was applied. available soil phosphorus concentration increased over 13 ppm (critical p-bray 1 concentration for soybean) when 45 and 60 kg p2o5/ha rates were applied to both crops, reaching at the same time the highest residual phosphorus uptake efficiency. soybean yields were higher when p was applied to soybean, as compared to wheat treated with the same p rates. soybean highest p uptake efficiency was found when p was applied to soybean.