Ammonia Volatilization Losses from Urea Fertilizer Applied on Wheat

摘要

Ammonia (NH3) emissions represent a major loss of nitrogen (N) in agricultural production. A field experiment was performed in the Pampean region to evaluate the effect of different urea rates applied to wheat (Triticum aestivum L.) on NH3 losses through volatilization using a direct method (15N as tracer) and an indirect method (N-difference ). Volatilization was quantified using static semi-open N-NH3 collectors during eight d after fertilization with urea N at rates of 0, 50 and 100 kg/ha (WO, W50and W100) in 2008, and WO and W100 during 52 d in 2009. In both years, NH3 volatilization correlated with soil accumulated temperature during the first eight d after fertilization and the percent of N derived from fertilizer (%Ndff) increased markedly between 24-48 h after fertilization, especially in W100, where %Ndff reached 100 percent. The total NH3-N losses during the whole wheat growing season were 6.3, 7.4 and 9.6 kg/ha for WO, W50 and W100 in 2008, and 7.3 and 13.4 kg/ha for W0 and W100 in 2009, being significantly higher in W100. The N-NH3 losses, in proportion to the fertilizer applied, were 2.2 and 3.3 percent for W50 and W100 using the indirect method, and 0.9 percent and 3.3 percent for W50 and W100 by the direct method, and 6.2 percent for W100 by both methods in 2009. There were no significant differences between methods. Volatilization under wheat increased with rate of urea application but the losses were less than 6.5 percent of the applied fertilizer.