Volatilização de amônia após aplicação de doses de ureia sobre capim-Marandu

Abstract

Nitrogen fertilization provides morphological improvements such as canopy height, leaf and root biomass. However, its management has high cost and low efficiency due to volatilization. The objective was to quantify the volatilization of ammonia (N-NH3) after the application of doses of urea in the straw on Marandu grass. The experiment was installed in the geographical coordinates 15°52'29 "S and 52°18'36 "O, inside UFMT, Barra do Garças/MT. The experimental design was in randomized blocks (BCT) with six N doses (0, 60, 120, 180, 240 and 300 kg ha-1) using urea with 45% N as source, and four repetitions totaling 24 experimental plots. The SALE chamber was made of transparent plastic bottles (PET), with a usable area of 0.008 m2, inside was installed the absorber system composed of a 3 mm thick polyethylene foam sheet soaked with the capture solution contained in a 70 mL plastic bottle. The foams were collected and replaced on days 1, 3, 5, 9, 15 and 20 after the application of treatments. The data were submitted to variance analysis using the F test and, when significant, linear regression was performed. The highest ammonia volatilization was found with the dose of 300 kg ha-1 of N in the first and fourth collection, being the first collection the one that presented the highest volatilization, corresponding to 10,5 kg ha-1 of the dose of 300 kg ha-1 applied. In the first collection an increase of almost ten times in volatilization was observed in relation to the applied doses while in the fourth collection there was a four times increase in ammonia volatilization in relation to the applied doses. Ammonia losses increased with increasing doses of urea.