Cotton Growth and Nutrient Uptake after Rock Phosphate, Gliricidia Prunings or Chemical Fertiliser Application in Soils of Semiarid Northeast Brazil

Several studies have demonstrated that organic fertilisers or ground rocks may be a viable alternative to industrialised chemical fertilisers in some agricultural systems. The present study aimed to compare the effects of ground phosphate rocks, gliricidia prunings and chemical fertilisers as nutrient sources to cotton (Gossypium hirsutum L.) cultivated in two types of soil (Fluvic Entisol and Oxisol) of the Brazilian semiarid northeast region. The experiment was conducted in a greenhouse at the Federal University of Pernambuco, in a completely randomised design with twelve treatments and four replications, consisting of three phosphate sources (MB-4 rock powder, Bahia rock powder and triple superphosphate), two nitrogen sources (urea and gliricidia) and a control without fertilisation. The aboveground biomass of cotton plants in the second growing cycle showed higher values of nitrogen with the combined use of gliricidia and MB4. The results indicated that the uses of green manure combined with natural phosphate may be a viable alternative to supply phosphorus and nitrogen to cotton plants in the Brazilian semiarid region. This can be a potential source of phosphorus and nitrogen in familiar agriculture and can replace mineral fertilisation.