Evaluación de la eficiencia agronómica de cuatro formas de urea en el cultivo del arroz

Nitrogen is the nutrient with greatest influence on yield and cost production of rice; it is then necesary to look for its most efficient use. Three field experiment were carried out to determine the agornomic efficiency of four urea forms (prilled, forestry grade, supergranules and sulfur-coated) at different rates and plant growth stages of CICA 8 variety. Results indicate that application before of three urea form-sulfurcoated urea excepted-brings about the loss of nitrogen; the related rice yield thus depended on the native nitrogen. Puddling allows a better plant use of soil nitrogen and increases rice yield by 76 percent with respect to dry soil planting but does not improve applied nitrogen efficiency. Split applicatin of 100 kg/ha N of all the above urea forms (1/3 before planting and 2/3 at panicle onset) increases the applied nitrogen absorption and greatly enhances nitrogen agronomic efficiency. Similar application of sulfurcoated urea increase rice yield by 20 percent and also improve nitrogen agronomic efficiency (44.0) when compared to the conventional system (27.4)