Maria da Conceição Santana Carvalho1, Alexandre Cunha de Barcellos Ferreira1, and Marisa de Cássia Piccolo2. (1) Brazilian Agricultural Research Corporation - Embrapa, Rodovia BR 153, km 04, CP 714, Goiânia, 74230-030, Brazil, (2) Centro de Energia Nuclear na Agricultura - CENA/USP, Avenida Centenário, 300, Bairro São Dimas, Piracicaba, 13416-000, Brazil
The Cerrado region is responsible for more than 87% of the total area of 1,093 thousand hectares where cotton is cultivated in Brazil and over 92% of lint production. Taking into consideration the expansion of no-tillage system and the aspects related to crop succession/rotation, farmers have been searching for options regarding period and method of fertilizer application, aiming mainly at higher operational yields, higher efficiency of fertilizer use, and cost reduction. The objective of this study was to evaluate the efficiency of anticipating all the cotton topdressing nitrogen fertilization or part of it to cultivate the preceding grass species (Brachiaria brizantha) under no-tillage system and crop-livestock integration in the Brazilian Cerrado. For that, a field assay was carried out in the state of Goiás, in 2004/2005 and 2005/2006 growing seasons, in an area of soil classified as Typic Haplustox. We applied 120 kg/ha of N as ammonium nitrate. The experiment consisted of 12 treatments in a randomized complete block design with four replications, in a 5x2+1+1 factorial arrangement: five methods of fertilizer application (100% pre-planting; 75% pre-planting + 25% topdressing; 50% pre-planting + 50% two topdressing applications; 50% pre-planting + 50% topdressing; and 25% pre-planting + 75% two topdressing applications), two periods of pre-planting application (before and after desiccation of brachiaria), one treatment of conventional fertilization (two topdressing applications), and one contro. The results indicated that, the anticipation of cotton nitrogen fertilization for the brachiaria resulted in the same lint yields as with conventional fertilization using two topdressing applications. Furthermore, pre-planting application resulted in higher production of brachiaria mulch to cover the soil, incorporation of nitrogen applied in biomass (brachiaria and soil microbial biomass), and controlled liberation of nitrogen through mineralization, which makes its absorption by the cotton plants possible in the period of their higher demand.
