Coeficientes de cultura para o arroz de terras altas em função da porcentagem de cobertura morta do solo.

Abstract

Sprinkler irrigated upland rice water requirement can be estimated from evaporation pans using crop coefficients. Those coefficients depend, among others factors, on soil management system. Under no-tillage, soil mulch alters soil-water relationship, as prevent evaporation, reducing crop evapotranspiration rates and resulting in saving operation costs of irrigation system. The objective of this study was to determine crop coefficients to upland rice, cultivar Primavera, under notillage, on different percentages (0%, 50%, and 100%) of soil cover by Brachiaria mulch, using field water balance methodology. The complete cover of soil by mulch was effective in reducing water losses through evapotranspiration, specially in the initial stages of upland rice crop, resulting in saving 9.0% and 17.8% of water, respectively in relation to 50% of soil covered by mulch and soil uncovered. The maximum values of crop coefficient occurred in the spikelet initiation-booting stage and were respectively equals to 1.34, 1.31, and 1.28 for the uncovered soil, and for 50% and 100% of soil covered by mulch.