[Behaviour and agronomic effectiveness of urea and its derivaties on sandy soils]
1999
Dorneanu, Emilia | Dorneanu, A. (Institutul de Cercetari pentru Pedologie si Agrochimie, Bucuresti (Romania)) Bogdanescu, Victoria | Sonea, Victoria (Baza experimentala a Chimenerg, Craiova (Romania))
The paper is dealing with the biochemical transformation in sandy soil(Psammosol) of urea and its derivatives, including both the condensation compounds and those of addition. Laboratory studies show that hydrolysis of urea and its derivatives takes place differently according to the time, temperature and the properties of the type. The soluble fertilizers are characterized by a rapid hydrolysis, pH reaching the value 9 in the first 5 days, and the total losses by volatilization as ammonia in atmosphere, after 33 days, are of 26.2-27.4 percent. On the contrary, slow released nitrogen fertilizers are characterized by a slower hydrolysis, especially in the case of CDU, and the losses by volatilization are between 6.31 and 9 percent. The organo-mineral fertilizers and those slow released nitrogen ensured higher productive use degrees than urea its soluble derivatives (addition compounds). The urea and its soluble derivatives may be used with positive results on sandy soils, decreasing the most part of losses, if their application is split into 2-3 fractions.
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