Watermelon cultivation in the semi-arid irrigated with different heights of treated domestic sewage

ABSTRACT

The aim of this paper was to assess the agronomic viability of using anaerobically treated domestic sewage in cultivation of Crimson Sweet watermelon. In a field experiment conducted in the semi-arid region of Pernambuco state, Brazil, four treatments (T) were used to assess the effects of irrigation using dripping system on fruits and soil. Four heights of 50% (T1), 75% (T2), 100% (T3) and 125% (T4), based on the calculated evapotranspiration and irrigation needs, were applied. The treated effluent characteristics indicated compliance with the recommendations for agricultural application, but the concentration of suspended solids (114 mg.L^-1) demanded frequent cleansing of the dripper blockages. We observed an increase in the cation exchange capacity and a decrease of the soil pH in all the treatments. The best results were obtained with the treatment T4 (height of 125%), which showed watermelons of bigger size (20.78 cm), as well as the highest productivity (61.1 t.ha^-1) and fruit weight (7.12 kg.un^-1). These values are higher than those of the country and Pernambuco state, demonstrating the agronomic feasibility of reuse under the studied conditions.

Keywords:
reuse for agriculture; UASB reactor; agricultural productivity; dripping