Effect of nitrogen rates and split nitrogen fertilization on grain yield and its components in flooded rice

Juan Hirzel1*, Alberto Pedreros2, and Karla Cordero1

Nutritional management in rice (Oryza sativa L.) crops is mainly associated with N fertilization, which is difficult to adjust in field conditions due to variations in soil type and climatic conditions. Between 28 000 and 46 000 ha per year is dedicated to rice production in Chile and profits depend on fertilization. A field experiment determine the effect of N rates and split N fertilization on grain yield and its components was carried out in two locations during two consecutive seasons (2007 to 2009), where five N rates and five split N fertilizations were evaluated. The locations were in Parral (36º2’ S; 72º08’ W, Vertisol) and San Carlos (36º19’ S; 71º59’ W, Inceptisol), with N rates of 80, 100, 120, 140, and 160 kg ha-1 applied in different development stages, such as sowing, tillering, panicle initiation, and boot. Results indicate an important seasonal effect on grain yield. Yield increased with N rates higher than 120 and 140 kg ha-1 in San Carlos and Parral, respectively. Moreover, higher productivity with split N fertilization was (1) 33% of N at sowing, 33% at tillering, and 34% at panicle initiation or (2) 50% of N at sowing and 50% at panicle initiation. Yield components with the highest effect on productivity were affected by the evaluated split N. On the other hand, higher N rates increased the percentage of both stained and sterile grains per panicle.

Keywords: Irrigated rice, nitrogen management, rice productivity, Oryza sativa.
1Instituto de Investigaciones Agropecuarias INIA, Av. Vicente Méndez 515, Chillán, Chile. *Corresponding author (jhirzel@inia.cl). 2Universidad de Concepción, Facultad de Agronomía, Av. Vicente Méndez 595, Chillán, Chile.