Climatic and Soil Water Balances for the Melon Crop

The correct estimate of the water requirements of a crop, besides favoring its full development, also allows the rational use of water. In this context, this study aimed to evaluate water balance in the soil and estimated through climatic methods for the melon crop. Field water balance was daily determined along a period of 70 days. Climatic water balance was determined based on the reference evapotranspiration estimated by the methods of Penman-Monteith, Thornthwaite and Hargreaves-Samani. It was concluded that climatic methods do not estimate correctly water storage in the soil and, consequently, also the balance. Therefore, they should not substitute the soil water balance method to determine these variables. The water management for the melon crop based on evapotranspiration estimated through climatic methods results in overestimation of the water depth to be applied in the soil, in the initial growth stage, and underestimation in the periods of highest water demand.