Abstract
This study aimed to define areas suitable, and the irrigation water requirement for, cultivation of Tanzania guineagrass in the state of Ceara, Brazil. Tanzania guineagrass yield was estimated by a mathematical model, which considers the crop actual evapotranspiration, resulting from the crop climatological water balance. The water requirement throughout the year was estimated for soils with a water holding capacity of 20 (shallow soils), 40 (sandy soils), 60 (soils with medium texture) and 100 mm (clay soils). The relative frequency of occurrence of monthly productions greater than 2,750 kg DM ha(-1) month(-1) was obtained for different areas in Ceara, representative of most of the state's economic mesoregions. Tanzania guineagrass annual yields in the state of Ceara were between 20,000-30,000 kg DM ha(-1) year(-1). During the rainy season, the productive potential varies with the economic mesoregion, which presents different climatic conditions. The state of Ceara is only suitable for the rainfed production of Tanzania guineagrass for 4 months each year, predominantly from February to May, while weather conditions do not favor the development of this grass in the remaining months.