Effect of NPK fertilizer application on the performance of corn (Zea mays L.) in three major soil series of Isabela Philippines .

Response of corn to increasing levels of NPK fertilizer (30-30-30 kg/ha) in Benito Soliven and Jones sites and (90-60-60 kg/ha) in Gamu site was significant. The grain yield and the concentration and total uptake of N, P, and K increased correspondingly as the level of fertilizer applied increased. A fertilizer application of 90-60-60 kg/ha, i.e., more than six times the grain uptake of N, P, and K by the corn over the control. In Benito Soliven and Jones sites, the application of 30-30-30 kg/ha increased grain yield from 1.55 to 4.49 and 5.10 t/ha, respectively, i.e., three times the grain yield uptake of N, P, and K corn crop over the control. In Jones site, the application of N, P and K by corn crop over the control, more than double the grain uptake. Nonetheless, the optimum concentration on mineral nutrients in the plant tissue was not obtained. The average uptake of mineral nutrients corn per hectare in the three sites with 53,333 plants indicated that in Gamu a yield of 2.50 t/ha showed a nutrient uptake of 38 kg N, 6.39 kg P, 14.20 kg K, 0.107 kg Ca and 2.15 kg Mg. In Benito Soliven site, a yield of 4.79 t/ha showed a nutrient uptake of 37.49 kg N, 6.92 kg P, 14.59 kg K, 0.06 kg Ca, and 2.37 kg Mg. In Jones-site, a yield level of 5.10 t/ha, showed a nutrient uptake of 59.80 kg N, 8.74 kg P, 20.22 kg K, 0.14 kg Ca and 4.06 kg Mg. Application of 90 N kg/ha increase the demand for P and K by corn. However, higher rate of N applied rendered the plant susceptible to lodging. To determine the existing practices for possible adoption of fertilizer, 22 corn farmers were interviewed. The average age of the respondents was 40 years and the average length of using fertilizer in corn farming was 4 years. The average farm size cultivated by corn farmers was 3.45 ha but majority were share-tenant.