Skip to main content
ARS Home » Pacific West Area » Kimberly, Idaho » Northwest Irrigation and Soils Research » Research » Publications at this Location » Publication #245561
Title: Managing runoff water quality from recently manured, furrow irrigated fields

Author
item Lentz, Rodrick
item WESTERMANN, DALE - Retired ARS Employee

Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2010
Publication Date: 5/14/2010
Citation: Lentz, R.D., Westermann, D.T. 2010. Managing Runoff Water Quality From Recently Manured, Furrow Irrigated Fields. Soil Science Society of America Journal. 74(4):1310-1319.

Interpretive Summary: Furrow irrigation is employed on 12.5 million acres of crop land in the U.S. and tens of millions more internationally. Nutrient losses in furrow irrigation runoff, which potentially increase when soils are amended with manure, can enter natural surface waters via return flow and become a potential source of contamination. We evaluated the effect of tillage, water soluble polyacrylamide (WSPAM) and irrigation management on runoff water quality during the first furrow irrigation on a calcareous silt loam soil, which had received dairy manure applied in the fall. We measured sediment, dissolved organic carbon, nitrates, ammonia, dissolved phosphorus, and total phosphorus concentrations in irrigation furrow runoff. Delaying the first irrigation until spring or treating the fall irrigation with WSPAM reduced runoff sediment and nutrient losses 80 to 100% relative to Fall-Controls. Moldboard plow tillage reduced runoff dissolved phosphorus losses 58% compared to rototill tillage. A buried lateral furrow system decreased runoff losses for sediment 89%, dissolved organic carbon 90%, and total phosphorus 82% relative to conventional irrigation. This research is the first to demonstrate that these management practices can substantially reduce offsite nutrient transport during the first irrigation on manured, furrow-irrigated fields.

Technical Abstract: Nutrient losses in furrow irrigation runoff potentially increase when soils are amended with manure. We evaluated the effect of tillage, water soluble polyacrylamide (WSPAM) and irrigation management on runoff water quality during the first furrow irrigation on a calcareous silt loam soil, which had received 45 Mg/ha (dry wt.) dairy manure applied in the fall. In Exp. 1 the amended soil was rototilled and irrigated that fall; furrow inflows were either treated with 10 mg/L WSPAM injected into furrow inflows only during furrow advance (Fall-WSPAM), or were untreated (Fall-Control). In Exp. 2 the first irrigation on the amended soil was delayed until the following spring and treatments included rototilled WSPAM (Spring-WSPAM) and untreated rototilled (Spring-Control), or moldboard-plowed soils (Spring-Moldboard). Exp. 3 also delayed irrigation until spring and compared conventional vs. buried lateral furrow irrigation systems. We measured sediment, dissolved organic carbon (DOC), NO3-N, NH4-N, dissolved reactive P (DRP), and total P (TP) concentrations in irrigation furrow runoff. Runoff mass losses from Fall-Control furrows were relatively large: sediment, 4505 kg/ha; DOC, 10.7 kg/ha; NO3-N, 28.1 g/ha; NH4-N, 68.1 g/ha; DRP, 132 g/ha; and TP, 3381 g/ha. Delaying the first irrigation until spring or treating the fall irrigation with WSPAM reduced runoff component losses 80 to 100% relative to Fall-Controls. The Spring moldboard plow reduced runoff DRP mass losses 58% compared to spring rototill (Spring-Control). The buried lateral furrow system decreased runoff losses for sediment 89%, DOC 90%, and TP 82% relative to conventional irrigation. Results from this research demonstrate that several types of management approaches may be successfully employed to substantially reduce offsite nutrient transport during the first irrigation on manured, furrow-irrigated fields.