Production of castor bean under combination of phosphorus sources and liming

Castor bean is considered a demanding crop in phosphorus and adequate phosphorus nutrition with reactive sources in conjunction with natural sources can increase the efficiency of absorption of phosphorus and castor bean productivity. This research aimed to evaluate the yield components of castor bean under combinations of fertilization with reactive and natural phosphate, in the absence and presence of lime. The study was conducted in a 2 x 5 factorial design, involving two doses of limestone (with and without lime), and five combinations of phosphorus fertilization: control (0 kg ha^-1 de P₂O₅), 100% of natural phosphate (560 kg ha^-1), natural phosphate (560 kg ha^-1) + MAP (188 kg ha^-1); natural phosphate (560 kg ha^-1) + ½ MAP (94 kg ha^-1) and 100% MAP (188 kg ha^-1), with four replications in a randomized block design. The length of the primary and secondary racemes, number of berries, shell weight, berry weight, grain weight, weight of 100 grains and ratio between grain and berry weight were evaluated. The combination of MAP + natural phosphate in the presence of limestone resulted in higher production of castor beans (1455 kg ha^-1), and increased most of studied production components.

natural phosphate; monoammonium phosphate; berry weight; grain weight