Water conditions and plant growth of important crops for indigenous communities of Brazilian semiarid

ABSTRACT

The Brazilian semiarid region is characterized by extreme interannual rainfall variability, such that knowledge of the beginning and end of the rainy season contributes to avoiding uneconomic crops and consequent losses. The aim of this study was to relate the estimates of water conditions to the growth season and development of major crops for indigenous communities in the semiarid northeast, considering three different climatic scenarios. Monthly estimates of potential evapotranspiration (ETP) for each location were estimated through the method of Thornthwaite (1948) and transformed into 10-day averages. The variables 10-day distribution of precipitation, full ETP, and half ETP were used to characterize the growth phase of cowpea, cassava, and maize, along with the determination of pre-humid, humid, and post-humid periods. The results showed that, in the semiarid northeast region of Brazil, it is not possible to have an agricultural annual planning for rainfed crops in dry years. Only for the location of Banzaê, BA-Quijingue, BA, in normal and rainy scenarios, it was possible to predict times of less probability of crop risk, starting from the determination the onset, duration, and end of each sub-period and the growth of each crop, which are 31/01 to 23/09 and 10/12 to 12/09 for cowpea, 31 / 01 to 01/11 and 10/12 to 21/10 for cassava, and 31/01 to 03/10 and 10/12 to 22/09 for corn, in the same order as the precipitation scenarios. There is great variability and irregularity of periods of 10-day rainfall throughout the year in the locations studied.

Keywords:
decendial rain; evapotranspiration; phenological cycle; indians