POTENCIAL, ECONOMIA DE ÁGUA E ADUBAÇÃO COM A APLICAÇÃO DE EFLUENTE DO TRATAMENTO PRELIMINAR DE ESGOTO DOMÉSTICO NA FERTIRRIGAÇÃO DE CAPIM-ELEFANTE.

Fertigation as an alternative of final disposal of domestic sewage is a viable solution, considering the low cost of its implantation, the use of nutrients by the plants and the obtaining of improvements in the soil structure. In this work, the potential of the effluent of the preliminary domestic sewage treatment (PST), the water savings in irrigation and fertilization, will be evaluated, considering its chemical quality for elephant grass (Pennisetum purpureum) fertigation. Each experimental plot consisting of 4 planted lines and 3 water/domestic sewage application grooves, between 0.6 m and 40 m long lines. Two treatments were imposed: T1 - application of conventional chemical fertilization and drinking water, in irrigation; and T2 - application in PST fertigation, being the water requirement of the plants complemented with water from the supply network. The application rate of EDP was established considering its chemical characteristics and the nutritional and water needs of elephant grass. The results showed that the EDP used in elephant grass fertigation, considering an application sheet for to supply 300 kg ha-1 ano-1 of Na, was able to supply 100% P2O5, 33% K2O, and 93% N of elephant grass needs, generating a financial savings of US$ 445.00 ha-1 for fertilization; US$ 624.00 ha-1 of the production costs; and US$ 6.00 ha-1 of the irrigation costs, providing a total saving of US$ 630.00 ha-1 and a saving of 58% of the total water demanded. [ABSTRACT FROM AUTHOR]