Submitted to: Journal of Production Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 25, 1996
Publication Date: N/A
Interpretive Summary: Irrigated crop production is critical to global agricultural output. Surface irrigation, mostly furrow irrigation, accounts for >60% of Earth's 240 million irrigated ha. Erosion seriously threatens irrigation's ability to sustain its 2X yield advantage over rainfed agriculture and risks environmental and food security consequences to earth's growing population. Furrow irrigation-induced erosion is nearly eliminated by small additions of water-soluble polyacrylamide (PAM) to irrigation water. PAM is an environmentally safe flocculent used in municipal water treatment, food processing and other sensitive applications. On freshly cultivated furrows, 1 kg/ha of PAM applied in irrigation inflows at 10 g/m3 during water advance (only), reduced runoff sediment 94% and increased net infiltration 15% in 3 yrs of tests in Idaho. The Natural Resources Conservation Service published a PAM- use practice standard in January 1995. In 1995, the 1st year of product sales, 20,000 ha of furrow irrigated land used PAM, halting 0.9 million metric tons of erosion. With PAM-use, irrigation return flows have had reduced sediment, biochemical oxygen demand (BOD), total phosphorus, and various pesticides. Many irrigation farmers who have viewed traditional conservation practices as cumbersome, intrusive, or ineffectual, adopt PAM-use as an attractive inexpensive alternative. The typical $37- $88/ha per crop costs, are partially or entirely retrieved by savings in erosion-related field operations, improved infiltration, water conservation, or crop responses. Pam-use is expected to expand rapidly in 1996.
Technical Abstract: Irrigated cropping is a critical component of global agricultural production. Surface irrigation accounts for more than 60% of Earth's 600 million irrigated acres, most of which is furrow irrigation. Erosion threatens irrigation's ability to maintain its 2X average yield advantage over rainfed agriculture, with serious environmental and food security consequences to the burgeoning human population. Furrow irrigation-induced erosion is nearly halted by small additions of water- soluble polyacrylamide (PAM) to irrigation water. PAM is an environmentally safe flocculent used extensively in municipal water treatment, paper manufacturing, food processing and other sensitive applications. On freshly cultivated furrows, 1 lb/acre of PAM applied at 10 ppm in irrigation water before runoff begins (only), reduced sediment loss in runoff 94% and increased net infiltration 15% in 3 yrs of Idaho tests. PAM products are now registered in most western states and NRCS has published a PAM-use practice standard. Cost sharing is available in some areas. In 1995 about 50,000 acres of furrow irrigated land used PAM, to halt as much as 1 million tons of erosion in the first year of PAM sales. Irrigation return-flow quality is improved by PAM- use, greatly reducing sediment, BOD, total P, and various pesticides with PAM-use. Farmers see PAM-use as an attractive alternative to more difficult conservation practices. The typically $15-$35 per acre per crop costs, are partially or entirely retrieved by crop responses or by savings in erosion-related field operations and water conservation. Pam-use in irrigation is expected to expand rapidly in 1996.