Pesquisa Agropecuária Tropical
On-line version ISSN 1983-4063
AQUINO, Leonardo Angelo de et al. Phosphorus split application on irrigated cotton. Pesqui. Agropecu. Trop. [online]. 2012, vol.42, n.1, pp. 1-8. ISSN 1983-4063. http://dx.doi.org/10.1590/S1983-40632012000100001.
Most regions where cotton is cultivated in Brazil present low soil fertility, especially concerning the available phosphorus (P). This study aimed to evaluate the phosphorus split application on irrigated cotton, for reaching a higher phosphate fertilization efficiency, in comparison to the traditional application at sowing. The experiment was conducted in Quartzarenic Neosol with 22 mg dm-3 of P (medium availability), in the north region of the Minas Gerais State, Brazil. The design used was randomized blocks, in a (4x3) + 3 factorial scheme, with three replications. Treatments consisted of P2O5 doses (0 kg ha-1, 30 kg ha-1, 60 kg ha-1, 120 kg ha-1, and 180 kg ha-1) and three split applications (80% and 20%; 60% and 40%; 40% and 60% of the P dose applied respectively at sowing and at 35 days after emergence (DAE)), plus the application of 0 kg ha-1, 60 kg ha-1, and 120 kg ha-1 of P2O5 at sowing. The P source was the granulated triple superphosphate, and the P content in the shoots increased according to the doses applied. Nutrient contents in the index leaf, except for P, were not influenced by P levels and split applications. The P content in the index leaf and the number of cotton bolls per plant increased with the increment of P doses, but were not affected by the phosphate fertilizer split application. The application of 40% of the P dose at sowing and the remaining amount split at 35 DAE decreased the cotton boll yield, with no significant effect for the other split applications.
Keywords : Gossypium hirsutum L.; cotton boll; phosphate fertilizing.