Abstract

SANCHEZ, Esteban et al. Nitrogen Use Efficiency in Pecan. Terra Latinoam [online]. 2009, vol.27, n.4, pp.311-317. ISSN 2395-8030.

Due to the increasing cost of fertilizers and the negative effect of their excessive use on the environment, a more rational way of nutrient application is needed. The present research evaluated nitrogen use efficiency (NUE), productivity and quality of pecan. Three N doses were evaluated (160, 320, and 480 kg ha^-1). Ammonium sulfate (20.5% N) was used as N source. N was split into seven applications during the following phenological phases: 1) pre-sprouting (late February to early March, with 12.5% of total N dose); 2) beginning of fruit set (middle to end of April, 25% of total N); 3) fruit growth (early June, 12.5% total N); 4) aqueous stage (mid July, 12.5% of N); 5) milky stage (mid August, 12.5% of N); 6) fruit ripening (middle to end of September, 12.5% of N); and 7) postharvest N application (mid December, 12.5%). At harvest, average yield per tree, number of nuts kg^-1, kernel percentage and NUE (kg of produced fruit kg^-1 of applied N) were evaluated. Results indicate that the maximum NUE was obtained with 160 kg ha^-1 which yielded 16.91 kg of nuts per kg^-1 of N applied, while 320 and 480 kg ha^-1 produced only 9.06 and 6.24 kg of nuts kg^-1 of N, respectively. The number of nuts kg^-1 was smaller with the treatment 160 kg ha^-1 (139 nuts kg^-1) when compared with 320 and 480 kg ha^-1 which yielded 140 and 142 nuts kg^-1 respectively. Regarding percentage of kernel, all three N-treatments showed a value of 54%. The optimum N dose for efficient use of nitrogen, pecan productivity and quality was the treatment with 160 kg ha^-1.

Keywords : Carya illinoinensis; efficiency; fertilization.