EVALUACIÓN DE REFERTILIZACION NITROGENADA BASADA EN LA UTILIZACION DE UN SENSOR OPTICO.

MELCHIORI, RJM; CAVIGLIA, OP; FACCENDINI, N; BIANCHINI, A; RAUN, W

Rosario, Argentina

Congreso; VII Congreso Nacional de Maíz; 2005

High nitrogen use efficiency (NUE) is an important way to contribute to improve maize productivity and profitability in a context of lower grain/nitrogen price ratio. Maize crop require high N availability to obtain high productivity, and in the pampas region N is commonly deficient. The objective of this experiment was to evaluate the crop yield and nitrogen use efficiency in two N management strategies: fixed rates, and sensor-based nitrogen calculated rates. We estimated NUE as a ratio between kg grain and N soil + N fertilizer. The experiment was conducted during 2004/2005 in Parana, Argentina (31,5 S). Treatments were tree N levels (NS) at planting (0N, 70 and 140 kg N/ha) and sidedress N applications in four crop stages: V8, V10, V12 and V14. Two sidedress N management methods (NM) were applied in each crop stage: sidedress in fixed rate (FR = 70 kg N/ha) and estimated with sensor-based nitrogen rate calculator (SBNRC). Average grain yield was higher in FR vs SBNRC, while a significant (p<0.05) interaction NS x NM was detected. NM x stage was significant (p<0.001) for NUE; in fact higher NUE with SBNRC method was obtained in latter stages (V12 and V14). Our results showed that SBNRC contributed to improve NUE in corn with slightly yield reduction.