|Lentz, Rodrick - Rick|
Submitted to: International Erosion Control Association Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 11/29/1995
Publication Date: N/A
Citation: N/A Interpretive Summary: Furrow irrigated fields are watered by directing water downward and across the field in specially formed furrows. These small streams cause soil erosion, which removes topsoil and reduces the soil's crop growth potential. Polyacrylamide (PAM) can be applied to soils in irrigation water to control soil losses from furrows. We compared several types PAM application strategies to determine which was most effective. PAM was applied to irrigation water in gated irrigation pipe as dry granules, or to furrow at the upper end of the field, as a solution. One of the most effective treatments applied 10 parts PAM per million parts irrigation water when water first flowed down the dry furrow. Equally effective was one that applied 5 parts PAM per million parts irrigation water initially, then reapplied PAM for 5-15 min episodically, for the remaining irrigation, at similar concentrations. When PAM was applied at an overall field rate of >0.7 kg/ha, furrow sediment loss was reduced by 94% and net infiltration was increased by 15%. These treatments were nearly twice as effective than one that continuously applied 0.25 parts PAM per million parts irrigation water. The best strategies protected furrows on slopes ranging up to 3.5%. Dry and solution applications controlled erosion about equally. PAM application was economical and effective method for controlling furrow erosion, under a broad range of field conditions.
Technical Abstract: Furrow-irrigation induced soil erosion threatens sustainable irrigated agriculture worldwide. This paper summarizes polyacrylamide (PAM) related field studies conducted on highly erodible Idaho silt loam soils. Field trials compared various PAM application strategies. PAM was applied to irrigation water in gated irrigation pipe as dry granules, or to furrow heads as a stock solution. Treatment efficacy varied primarily with irrigation inflow-rate, PAM concentration in irrigation water, duration of furrow exposure, and total PAM applied. The most effective treatments either applied PAM at 10 ppm in irrigation inflows during the furrow advance period (I,10,100%), or applied 5 ppm during the furrow advance, then reapplied PAM for 5-15 min episodically at similar concentrations (IE,5,100%). Over a range of application rates of at least 0.7 kg/ha PAM and mean of 1.3 kg/ha, treatments reduced furrow sediment loss by 94% and increased net infiltration by 15%. The full-advance I,10,100% and IE,5,100% treatments were nearly twice as effective as the continuous 0.25 ppm PAM application on these soils when slopes were 1-2%. The I,10,100% strategy protected furrows on slopes ranging up to 3.5%. Dry and solution applications controlled erosion about equally. PAM application was economical and effective method for controlling furrow erosion, under a broad range of field conditions.