Water requirement satisfaction index for coffee crops in Western Amazon /Indice de satisfacao da necessidade de agua para a cultura do Coffea canephora na Amazonia Ocidental

Water balance is a tool that has various applications in agriculture, including assessing whether an environment is suitable for growing a specific crop by providing information on how water resources function in the system. This information is essential for determining whether the available water satisfies the crops demand. Thus, the objective of this work was to calculate the water balance of Typic Hapludults for growing coffee (Coffea canephora) crops in Cruzeiro do Sul, Acre, Brazil, using a 36-year historical series to assess the potential and limitation of the crop according to the water availability. The results showed that coffee crops are, in general, suitable for growing in the study region. Water deficit and water surplus periods are well-defined, from April to August and September to March, respectively. Flowering was the only stage of coffee crops that coincides with the water deficit period in the region; thus, irrigation is necessary to prevent compromising this stage and fruit development. The Water Requirement Satisfaction Index (WRSI), calculated on a monthly basis, indicates a low climate risk for coffee crops in the region. However, when calculated on a daily basis, the WRSI shows a medium to high climate risk for coffee crops in several periods. The WRSI proved to be an adequate tool for assisting in decision-making regarding the adoption of irrigation. Key words: water availability, irrigation, crop water use O balanco hidrico e uma ferramenta com diversas aplicacoes na agricultura, incluindo a avaliacao da adequacao de um ambiente para o cultivo de uma determinada cultura, atraves da compreensao de como os recursos hidricos operam no sistema. Esta informacao e vital para determinar se a agua disponivel satisfaz a necessidade da cultura. Assim, objetivouse calcular o balanco hidrico em um Argissolo Vermelho-Amarelo para o cultivo de Coffea canephora no municipio de Cruzeiro do Sul, Acre, utilizando uma serie historica de 36 anos para avaliar o potencial e as restricoes da cultura de acordo com a agua disponivel. Os resultados mostraram que, de forma geral, o cultivo de Coffea canephora e adequado para a regiao de estudo. Os periodos de deficit hidrico e de excesso de agua sao bem definidos, ocorrendo de abril a agosto e de setembro a marco, respectivamente. Verificou-se que apenas a fase de floracao do cafeeiro coincide com o periodo de deficit hidrico na regiao, exigindo assim irrigacao para evitar comprometer essa etapa do desenvolv