Funções de produção de nitrogênio e água na cultura do milho irrigado no município de Sumé-PB.

Abstract

The present experiment was carried out with the objective to study effects of different treatments of irrigation water (based on available Mater use), and levels of nitrogen on corn (Zea niays L.) cultivar Centralmex using basin irrigation system. The experiment was conducted ia amedium textural alluvial eutrophic soil of medium texture of Irrigated Perimeter of Sumé - PB a part of National Department of Works Against Droughts (DNOCS) during the period of Oct. 29, 1985 ti Jan. 29, 1986. Foi" the evaluation of effects of treatments, the parameters like height of plants, total number of commercial corn, index of corn per plant, percentage of straw, yield of commercial corn with and without straw and quality of corn were studied. As practically no differences were observed among the treatments of irrigation water, the parameteres were analysed considering treatments of irrigation water as replications. The results obtained permit to conclude that heights of plants (41 days after sowing) were affected by levels of nitrogen. With respect to production and its components, the results of percentage of straw and yeld of corn with and without straw were found to be significant. The regression analysis linear effects of nitrogen levels on percentage of straw, while for the corn yield with and without straw the effects were found to be quadratic. For the estimation of real evapotransp iration of crop by water balance, daily determination of water content in soil profile were carried out by neutron probe. From the estimated real evapotranspiration value, crop coefficients for different phenological Phases of corn were calculated according to D00RENB0S & KASSAI1 (1979). On the basis of results, for the best yields of corn, 80 kgN/ha may be recommended, nevertheless, the indispensable need for a more detailed study in respect of total volume of water and frequency of irrigation to be used are pointed out.