Nutrient support via fertigation with domestic effluent and growth of cotton

Because of climatic problems in the Brazilian semi-arid region, it is of fundamental importance to seek a culture that considers water scarcity and available natural resources. Thus, a randomized block design, with subdivided plots and six replications, was carried out in the experimental area of the treatment and wastewater reuse station of the Milagres Settlement, Apodi, Brazil, with the objective of evaluating cultivation of herbaceous cotton (Gossipyum hirsutum) fertigated with domestic sewage treated in a semi-arid environment. Two cultivation cycles were carried out, and the cotton plants were fed with three different solutions containing treated domestic sewage (TDE) plus supply water (PSW), to supply the crop evapotranspiration (ETc) (100% PSW – control, 50% PSW + 50% TDE and 100% TDE), with and without phosphate fertilization in pre-planting. The contribution of nutrients to the soil and plant growth were analyzed. The results indicated that the wastewater presents potential fertilizer, reaching to the soil amounts of some nutrients exceeding the cotton’s needs, when 100% of the ETc was supplied via fertigation with domestic effluent, resulting in an increase in the growth rates of the plants. There was no interaction between the percentages of wastewater and phosphate fertilization in pre-planting. Phosphorus alone promoted significant variation only in the first cycle, indicating that there is a residual fertigation effect with domestic effluent on the nutrient supply.