Emitter clogging and distribution uniformity in nitrogen fertigation¹

Fertirrigação com nitrogênio no entupimento e na uniformidade de distribuição de emissores

ABSTRACT

Despite highly efficient, the main limitation of using drip irrigation for fertigation with nitrogen (N) fertilizers is the sensitivity of emitters to clogging by contaminants. The objective in this study was to assess the effect of different sources of N fertilizer and different operation times on water distribution uniformity and emitter clogging using a localized surface drip irrigation system. A randomized block experimental design with three replicates was used, in a 5 × 6 factorial arrangement consisting of five N sources (potassium nitrate, ammonium sulfate, calcium nitrate, ammonium nitrate, and urea) and six operation times (100, 200, 300, 400, 500, and 600 hours). The same nitrogen (N) rate applied in all treatments was equivalent to 100 kg ha^-1. The drip tubing used had a nominal flow of 2 L h^-1, nominal diameter of 16 mm, internal diameter of 13 mm, operating pressure of 100 to 350 kPa, and spacing between emitters of 0.7 m. The variables evaluated were: statistical uniformity coefficient, absolute uniformity coefficient, and degree of clogging. The best absolute and statistical uniformity coefficients were found when using urea and ammonium nitrate for fertigation, mainly at the longest operation times, which presented the best water application uniformity (>91.72%).

Key words:
urea; potassium nitrate; ammonium sulfate; calcium nitrate

HIGHLIGHTS:

Fertigation with nitrogen sources changes the water application uniformity in drip irrigation system.

Nitrogen application via fertigation causes partial clogging of emitters.

Fertigation and operation time affect the performance of irrigation system.