ABSTRACT


José F. Araos F.1 y Rafael Ruiz S.1
 
Two field experimentscarried out during 1976/77 and 1977/78 at La Platina Experiment Station (Santiago, Chile) indicated that urea was as efficient as chilean nitrate (natural NaNO3), for topdressing application to irrigated wheat at tillering time. This would indicate that possible losses as ammonia from urea would not be of practical importance under these conditions. Results may be explained by the fact that urea was incorporated into the soil by irrigation given 7 and 2 days after application, in each experiment. In addition, relatively low temperatures and the oceurrence of frosts and dews, may have minimized ammonia volatilization. The soil, a Santiago sandy clay loam with pH 8.2 and 5% of CaCO3 content, has a cation exchange capacity of 16 meq/100 g.
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1Ing. Agr. M.S., e Ing. Agr. Magister Scientiae, respectivamente, Programa de Fertilidad de Suelos, Estación Experimental La Platina, Instituto de Investigaciones Agropecuarias (INIA), Casilla 5427, Santiago, Chile.