Applying Polymers to Irrigation Water: Evaluating Strategies for Furrow Erosion Control

Adding dilute quantities of moderate-charge-density anionic polyacrylamide (PAM) to furrow irrigation watercan greatly reduce runoff soil losses and, in some cases, increase net infiltration. We evaluated different strategies foradding PAM to irrigation water to determine which was most effective. The PAM was applied to irrigation water in gatedirrigation pipe as dry granules, or to furrow inflows as a stock solution. Treatment efficacy varied primarily withirrigation inflow-rate, PAM concentration in irrigation water, duration of furrow exposure, and total PAM applied. Themost effective erosion-control treatments either (1) applied an initial dose of PAM at 10 mg L 1 in irrigation inflows onlyduring the furrow advance period; (2) applied an initial 5 mg L 1 dose, then reapplied PAM for 5 to 15 min episodicallyat similar concentrations; or (3) continually applied 1 to 2 mg L 1 to irrigation inflows. The full-advance treatmentreduced sediment loss by 93%, compared to 60% for the continuous 0.25 mg L 1 PAM application when slopes were 1 to2%. Dry and solution applications controlled erosion about equally. The PAM applications were economical and effectivemethods for controlling furrow-irrigation induced erosion, under a broad range of field conditions.