Corn Water Variables Assessments from Earth Observation Data in the Sao Paulo State, Southeast Brazil

Landsat satellite images and agrometeorological data were used together for modelling the crop coefficient （Kc） in irrigation pivots composed by a mixture of corn hybrids from a commercial farm for grains and silage, located at the northwestern side of Sao Paulo state, Brazil. After developing relationships between Kc and the accumulated degree-days （DDac） and having yield data for 2012 available, they were applied in the whole state, to upscale the crop water variables, during the GS （growing seasons） of a second-harvest crop from March to August. Spatial thermohydrological differences among the main corn growing regions were clear. The largest CWP （crop water productivity） values and SD （standard deviations） were for Itapetininga with an average value of 1.60 ± 0.43 kg m-3, while the lowest ones were for Presidente Prudente （0.81±0.21 kg m-3）. As corn is important for these growing regions, being inside of the priorities from the Brazilian Ministry of Agriculture, these results should be considered for a rational exploration, including both, irrigation and rainfed conditions, as the actual water scarcity can bring much competition with other non-agricultural sectors.