Artigos

Abstract: With the objective of determining maize’s specific water requirements in different soil cover conditions in a Cerrado region of Mato Grosso, Brazil, this study used the dual’s crop coefficient (Kc dual) approach, according to FAO methods. An experiment was carried out in 2016, with three treatments: without vegetation soil cover; soil cover of 4 t ha-1 and soil cover of 8 t ha-1 dry matter of brachiaria grass. The used methodology accounts for crop’s transpiration component (through its basal coefficient, Kcb) and soil evaporation component (through its coefficient, Ke), which were determined for initial, intermediate and final phases of crop development. Experiments were carried in lysimeters to determine crop’s evapotranspiration, and in microlysimeters to determine soil evaporation. Crop’s transpiration, on three soil coverage treatments, showed overall highest values for the treatment with greater coverage (Kcb maximum values of 0.88, 1.00 and 1.03 from the lowest to greater soil coverage), while between crop’s phases, coefficient values were always higher at the intermediate stage, presenting decreases with crop senescence. Soil evaporation was highest on treatment without coverage in all crop’s stages (Ke = 0.37-0.78) and lowest in the treatment with greater coverage (Ke = 0.11-0.35). Yields were higher on treatments with coverage (9929.18 and 9939.52 kg ha-1 for treatments with 4 and 8 t ha-1) and lower when cultivated in soil without cover (8264.67 kg ha-1). Despite relatively higher crop’s transpiration with greater soil coverage, this treatment was identified as the best management option in the assessed tropical region of Brazilian Cerrado, in terms of rational use of water, due to lowest losses through evaporation, as also providing the highest grain yields.

Keywords: basal crop coefficient, soil water, evaporation coefficient, lysimeter, Zea mays, Cerrado