Resposta da cana-de-açúcar irrigada, primeira soca, submetida à diferentes tipos e épocas de adubação de cobertura.

Abstract

This research had as objective to study under field conditions the response of first leaf sugarcane, cultivate SP 791011, in the coastal lands of Paraiba state, Brazil, using the alternatives of local organic and mineral topdressing manurings applied in differentiated doses and times. The experiment was accomplished in Capim farm, belonging to Miriri Distillery, UNIAGRO enterprise, located in the municipal district of Capim, Paraiba state, Brazil. The experimental design was entirely randomized, with three repetitions. The tested topdressing fertilizers were SC01 (630 kg ha1), 12-00-24 (400 kg ha"1) and urea (200 kg ha"1), applied in a single dose and parceled out in two doses, with and without organic manuring (600 kg ha"1). The analyzed parameters were: growth parameters (number of stems per hectare, stem length, stem diameter, internodes number and the stem weight); the technological parameters (soluble solids, sucrose content, fiber content, broth purity and the percentage of gross sugar); and the production parameters (stems mean productivity (SMP) and the gross yields of sugar (GYS) and of alcohol (GYA)). According to variance analysis, the types of fertilizers tested as well as their different application times didn't cause significant difference for none of the growth and technological parameters, but they were significant to 1% of probability for SMP and GYS, and to 5% for GYA, having the mean values of these variables been superior to the ones of the control. The largest SMP values were obtained for the treatments that used the fertilizers SC01 and 12-00-24 added with organic matter applied in two doses and for the treatment with urea applied in two doses. Those same treatments also had largest values of GYS, together with the treatment that used the fertilizer 12-00-24 and organic matter applied in only one dose. The Largest value of GYA was obtained by the treatment that used urea applied in two doses. Finally, it is concluded that the parcel in the application of the topdressing manuring associated to addition of organic matter contributed positively for the yield of the sugarcane, first leaf.