Effect of a friction-reducing additive on the drip irrigation uniformity with sugarcane vinasse

Fertigation using vinasse, a high nutrient residue, is a viable form of complementary soil nutrition. However, it represents a dangerous risk of contamination if not properly disposed of. The objective of this study was to evaluate the irrigation and fertigation uniformity using vinasse in a drip irrigation system with and without the addition of polyacrylamide (friction-reducing polymer) applied at a concentration of 0.01 kg m-3 (10 mg L´-1). The tests consisted of collecting flow from 16 drippers in the system. Four were selected from each of the four lateral lines (first emitter, those located at 1/3 and 2/3 of the length, and the last one). Uniformity was obtained by the coefficient of distribution uniformity (CDU), Christiansen’s uniformity coefficient (CUC), the total coefficient of variation (CVt), and the statistical uniformity coefficient (SUC). The CUC values after the addition of the polymer were 2.33% and 2.1% higher for water and vinasse, respectively. For the CDU, the addition of the polymer resulted in values of 6.07% and 5.3% higher for water and vinasse, respectively, and the SUC resulted in values of 3.99% and 3.83% for water and vinasse, respectively. We concluded that vinasse showed a lower average uniformity compared to water. However, when the friction-reducing agent was added, an increase was observed in the average uniformity in the drip irrigation system.