WATER IN SOIL AND IRRIGATION CONVENIENCE IN PINEAPPLE GROWN IN NORTHIEASTERN COAST OF RIO GRANDE DO SUL

Abstract

Adequate soil management may increase its permeability and water storage and allow to estimate the irrigation requirements for growing pineapple in the northeastern coast of Rio Grande do Sul state, Brazil. Evapotranspiration data of the period 1980-1990, as wel I as temperatures from 1956 to 1999, and rainfall from 1931 to 1960, for this region, were compared with the conditions when irrigation is indicated. At Estação de Pesquisa e Produção of FEPAGRO, in Maquiné - RS, was conducted an assay to study the effects of soil management (conventional tillage, strip-tillage and no-tillage), in the main plots, and planting techniques (furrow and spear), in the subplots, on the soil gravimetric moisture. Soil management and planting techniques did not affect the gravimetric moisture. In Maquiné the average rainfall is 1,650 mm/year, above the required for pineapple (1,000 to 1,500/year). The analysis of evapotranspiration, and temperature data collected at the experiment station indicates no need of irrigation for pineapple culture in this region. Therefore, during the period of intensive growth, when water needs increases, and under conditions of low rainfall, such as the period of November-December, and April-May, irrigation might be necessary.