Nitrogen losses by ammonia volatilization of three clayey soils treated with urea - DOI: 10.4025/actasciagron.v26i4.1809

Abstract

The soil nitrogen (N) losses in gaseous form depend on their intrinsic characteristics and also on the environmental conditions. In soils with the same texture class, the mineralogy of the clay size fraction and the amount of organic matter are the main factors that may affect the N dynamics. In the State of Paraná northerner region, variations in these characteristics are found in the toposequence of soils derived from basalts where, in the landscape upper part, highly weathered soils, such as the Latosols, are found and, in the other sections, younger soils, such as Neosols and eventually Vertisols, are found. The aim of the present work was to evaluate the N volatilization losses from ammonia, using three clayey soils (Red Dystroferric Latosol-LVdf, Litholic Neosol-RL and Ortic Hydromorphic Vertisol-VGo) submitted to two soil moisture contents (S8 and SS) and treated with urea. The ammonia volatilization of the applied urea was evaluated in 2000cm³ plastic recipients that received 500g of soil and 200mg of urea, for an accumulative period of 10 days. Paper filter collectors, previously humidified with H₂SO₄ measured the N-NH₃ losses, which were placed 5cm above the soil surface. The results showed that the soils presented differences in the ammonia losses, related to the initial soil moisture contents and the mineralogy of the clay size fraction. In the lower moisture treatment (S8) the least weathered soils (RL and VGo) showed the lowest ammonia losses, due to the higher percentages of 2:1 clay type minerals. In the soil-saturated treatment the N-NH₃ losses were not statistically significant among the soils