Productivity and nutrient extraction by Brachiaria brizantha fertigated with treated sewage effluent

The present study was performed to evaluate the responses in productivity and nutrient extraction in dry biomass of Brachiaria brizantha ‘Marandu’ fertigated with treated sewage effluent (TSE) from 2013 to 2014, in Jaboticabal, São Paulo, Brazil. A triple line source sprinkler system was used to perform uniform but gradual irrigation of TSE and mineral fertilization in five treatments, with the following TSE fractions in water: 1.0 (E5); 0.87 (E4); 0.6 (E3); 0.31 (E2), and 0.11 (E1). In addition to fertigation, all treatments were supplemented with P and K. TSE was applied at depths of 1,853 and 2,253 mm year-1 in 2013 and 2014, respectively. This provided E5 with the following amounts of N, P, K, and Na (kg ha-1): 931, 27, 314, and 894, in 2013, and 1,132, 21, 463, and 1,428, in 2014. The most relevant effects on B. brizantha dry biomass yield and nutrient extraction were obtained with higher doses of TSE. The extract of macronutrients was higher for K and N, followed by K, Ca, Mg, and Na. Based on the responses in productivity and nutrient extraction of soil by the crop as a function of TSE fertilization without soil contamination, we propose that increased fertilizer application be studied further.