The present project was developed between march and july 2000, in Buenos Aires Distric, Picota Province (San Martín región), Perú, South América; located in 76º22'55" west longitude and 06º 22' 15" South latitude and 215 meters above sea level. We worked eiht "corn" (AG - 612 hybrid) and three NPK fertilizer dose under conditions of "complementary watering". The costs of production and treatments and relation between "benefits/cost" have also been vegetative characteristics have been determined as well. We used a "statistic block design" absolutly "ramdomized"; the factorial arrangement was 3x3x3 with 27 treatments and three repetitions each treatment which results were verified by "variance analysis", the Duncan test and the variability coeficient. The experimental soil was loamy soil, having pH 8.16 of alkaline reaction, with high contains of organic material (4.43%), the average...