ABSTRACT
Nitrogen and phosphate fertilization of rice in the central-south zone of Chile. Effect on grain yield

Carlos Rojas W.1 y Roberto Alvarado A.1
 

During the 1972/73, 1973/74 and 1974/75 growing seasons, 20 NP fertilization trials were set up in flooded rice fields located in the Talca, Linares and Ñuble provinces. The trials (incomplete factorial) included 5 rates of nitrogen (0, 60, 120, 180 and 240 kg/ha) and 5 rates of P2O5 (0, 50, 100, 150 and 200 kg/ha).
The mains conclutions were:
— Phosphorus fertilization did not affect significantly (P 0,05) the foliar phosphorus concentration. The grain yield was not aftected by increasing arnounts of applied phosphorus fertilizer.
— The foliar nitrogen concentration and the grain yleid were increased by nitrogen fertilization in 16 trials out of the 20 trials.
— Three response groups to nitrogen fertilization were detectecl. These were related to the intensity of use of the soil and to the effect of dry periods (“secas”) induced by sorne of the growers.
— Nitrogen tertilizer efficiency was satisfactory, but was low in the fields that were subjected to dry periods (‘secas’) during the plant clevelopment season.

Keywords:
1 Ing. Agr., M.S. e Ing. Agr., respectivamente. Estación Experimental Quilamapu (INIA), Casilla 426, Chillán, Chile.