MULTIPLE POLYACRYLAMIDE APPLICATIONS FOR CONTROLLING SPRINKLER IRRIGATION RUNOFF AND EROSION
Applied Engineering in Agriculture
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 erosion than applying the same total amount of PAM with a single irrigation. This study was conducted in the laboratory with a Rad silt loam (coarse silty, mixed,
... se silty, mixed, superactive mesic Durinodic Xeric Haplocambid) at 6.5% slope. Water was applied at 80 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 three irrigations (multiple). Both multiple and single PAM treatments caused significantly less runoff than the control for all four irrigations. However, the multiple PAM treatment reduced runoff approximately 30% more than the single application during the last two irrigations. Applying PAM at 3 kg ha-1 (2.7 lb a-1 ) with one irrigation reduced cumulative soil loss by 60% compared to the control. Applying PAM at the same rate in three consecutive irrigations reduced cumulative soil loss by 80%. Both single and multiple PAM applications reduced runoff and soil loss, but multiple applications more effectively controlled runoff longer than a single application.