|Foerster, James - Jim|
Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2002
Publication Date: 12/1/2003
Citation: Sojka, R.E., Morishita, D.W., Foerster, J.A., Wille, M.J. 2003. Weed seed transport and weed establishment as affected by pam in furrow-irrigated corn. Journal of Soil and Water Conservation. 58(5):319-326. Interpretive Summary: ARS Scientists from the Northwest Irrigation and Soils Research Laboratory at Kimberly, ID, and collaborators from the University of Idaho have found and documented a new benefit of using polyacrylamide (PAM) to control irrigation induced erosion. Results from a recent two year study in irrigated corn showed huge reductions in the weed seed concentration of runoff when using PAM. In addition to the now well recognized erosion prevention and infiltration enhancement benefits, PAM use reduced runoff loss of weed seeds (barnyardgrass, kochia, redroot pigweed, common lambsquarters, and hairy nightshade) 62 to 90%. This will greatly reduce the spread of weeds via runoff, both within individual fields and within irrigation districts via the collection and reuse of return flow water. Particularly with the growth of site specific herbicide application technologies, and with the general reduction of weed vectoring, this benefit of PAM use is expected to significantly reduce herbicide requirements. Reduced herbicide need benefits the farmer economically as well as reducing his or her exposure to chemicals and reducing agrichemical loading of the environment. PAM is an inexpensive environmentally safe food grade polymer that has been used for decades to purify potable drinking water around the world and for various other sensitive food, environmental and industrial uses.
Technical Abstract: Polyacrylamide (PAM) has been used successfully to reduce erosion and increase infiltration on nearly a half million hectares of U.S. irrigated farmland. PAM is a potent and environmentally safe flocculent that greatly accelerates separation of suspended solids from water. It also improves particle cohesion, stabilizing soil structure. We hypothesized that in irrigation furrows PAM prevents loss of weed seed and might affect weed establishment and management practices. We grew corn (Zea mays L.) in plots without herbicides, or that were treated with either Eradicane (EPTC + dichlormid) or Dual II (S-Metolachlor) and irrigated in furrows that had either no PAM, or that were treated either with 10 g/cubic meter (10 kg/ML or10 ppm) dissolved PAM during water advance, or with PAM applied as a powder patch at the furrow head. As in previous studies, erosion was greatly reduced with PAM and infiltration was increased. PAM use also reduced runoff loss of weed seeds (barnyardgrass, kochia, redroot pigweed, common lambsquarters, and hairy nightshade) 62 to 90%. Interactions of herbicide treatments and PAM on erosion, infiltration and weed-seed-loss were related to the mulching effect of weed vegetation. PAM is an effective and environmentally safe means of reducing weed seed distribution in furrow irrigation water while simultaneously reducing erosion and increasing infiltration in weed-free crop production.