MULTIPLE POLYACRYLAMIDE APPLICATIONS FOR CONTROLLING SPRINKLER IRRIGATION RUNOFF AND EROSION

Abstract

Runoff under sprinkler irrigation systems causes soil erosion and reduces water infiltration uniformity.Previous studies have shown that applying polyacrylamide (PAM) with irrigation water can reduce runoff and soil loss.We hypothesized that applying PAM with three consecutive irrigations would more effectively control runoff and erosionthan applying the same total amount of PAM with a single irrigation. This study was conducted in the laboratory with aRad silt loam (coarse silty, mixed, superactive mesic Durinodic Xeric Haplocambid) at 6.5% slope. Water was applied at80 mm h 1 (3.2 in. h 1 ) for 10 min [13 mm (0.5 in.) application depth] for four irrigations. PAM was applied at 3 kg ha 1(2.7 lb a 1 ) with irrigation water during the initial irrigation (single) or at 1 kg ha 1 (0.9 lb a 1 ) during the first threeirrigations (multiple). Both multiple and single PAM treatments caused significantly less runoff than the control for allfour irrigations. However, the multiple PAM treatment reduced runoff approximately 30% more than the singleapplication during the last two irrigations. Applying PAM at 3 kg ha 1 (2.7 lb a 1 ) with one irrigation reduced cumulativesoil loss by 60% compared to the control. Applying PAM at the same rate in three consecutive irrigations reducedcumulative soil loss by 80%. Both single and multiple PAM applications reduced runoff and soil loss, but multipleapplications more effectively controlled runoff longer than a single application.