DOSES DE NITROGÊNIO E DE FÓSFORO RECOMENDADAS PARA PRODUÇÃO ECONÔMICA DE MILHO-VERDE NA CHAPADA DO APODI-RN

Abstract

The nitrogen (N) and phosphorus (P) generally are the two nutrients that occur in lower levels in the soil in relation to the need of the plant and are the nutrients most required by the maize crop. With the present work aimed to define the levels of N and P2O5 associated to the maximal economical of green corn in an alkaline soil of the city of Baraúna-RN. The maize hybrid AG 1051 was planted in spacing of 0.70 x 0.23 m and harvested on the condition of green corn to 75 days after planting. Were applied 17 treatments, being 16 treatments resulting from the combination between four doses of N (30, 60, 90 and 120 kg ha-1) and four doses of P2O5 (30, 60, 90 and 120 kg ha-1) and a control treatment, in which not applied any dose of these nutrients. The experimental design was in randomized blocks with four repetitions. The characteristics evaluated were: number and total weight of cobs, number and weight of marketable covered cobs and number and weight of marketable uncovered cobs. The increase of the availability of N and P in soil, as a result of fertilizing, positively influences positively the weight of green maize ears. The culture of green corn responded better to phosphorus fertilization than nitrogen fertilization, showing that in the soil of the experimental area the P was more limiting to the production than the N. Although the majority of production of marketable covered cobs has been estimated for the application of 120 kg ha-1 N + 106 kg ha-1 P2O5, the doses of maximum economic and environmental efficiency recommended were 60 kg ha-1 N + 106 kg ha-1 P2O5.