Aspectos morfogênicos, produtivos e emissões de gases do efeito estufa em pastagem de capim piatã com adubação orgânica e mineral

Abstract

The study was carried out to evaluate the productive and morphogenic characteristics of Piatã grass and the emission of N2O (nitrous oxide) and CH4 (methane), with fertilization from different nitrogen sources. Four treatments (control, urea, compost, and biofertilizer) were tested, in a randomized block design. The following parameters were evaluated: dry matter (DM) production, leaf appearance rate, phyllochron, leaf elongation rate, stem elongation rate, leaf senescence rate, leaf life span, number of live tillers, number of live leaves, and the emissions of N2O and CH4. Higher DM productions were observed for the treatment with urea in the summer, which was 67%, 44%, and 33% higher than control, compost, and biofertilizer treatments, respectively. The urea treatment also had the highest leaf appearance rate, with a 20%, 13%, and 13% higher in comparison to control, compost, and biofertilizer treatment, respectively. There was no difference for phyllochron (P>0.05), however, this was numerically smaller for urea treatment. The highest leaf elongation rates occurred during the summer for urea treatment. For the leaf senescence rate, there was no difference between treatments. The grass, when fertilized with urea, showed higher values of stem elongation rate and the number of live tillers. The emission of N2O was higher when the organic compost was used, however, biofertilizer presented high fluxes of N2O. It is concluded that fertilization with urea promoted higher grass growth rates, however, fertilization with organic compost presented the greatest balance between production and emission of greenhouse gases.