Managing Runoff Water Quality from Recently Manured, Furrow‐Irrigated Fields

Abstract

Nutrient losses in furrow irrigation runoff potentially increase when soils are amended with manure. We evaluated the effects of tillage, water‐soluble polyacrylamide (WSPAM), and irrigation management on runoff water quality during the first furrow irrigation on a calcareous silt loam soil that had received 45 Mg ha−1 (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−1 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), with WSPAM applied as in Exp. 1, and untreated rototilled (Spring‐Control) or moldboard‐plowed soils (Spring‐Plow). Experiment 3 also delayed irrigation until spring and compared conventional vs. buried lateral furrow irrigation systems. We measured sediment, dissolved organic C (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−1; DOC, 10.7 kg ha−1; NO3–N, 28.1 g ha−1; NH4–N, 68.1 g ha−1; DRP, 132 g ha−1; and TP, 3381 g ha−1 Delaying the first irrigation until spring or treating the fall irrigation with WSPAM reduced runoff component losses by 80 to 100% relative to Fall‐Control. The Spring‐Plow treatment reduced runoff DRP mass losses by ∼60% compared with Spring‐Control. The buried lateral furrow system decreased runoff mass losses for sediment, DOC, and TP by >80% relative to conventional irrigation. This research demonstrated that several management practices may be successfully used to substantially reduce offsite nutrient transport during the first irrigation on furrow‐irrigated, manure‐amended fields.

Manure and Fertilizer Effects on Carbon Balance and Organic and Inorganic Carbon Losses for an Irrigated Corn Field

“…3A and 3B) were 18 to 33% of the 34.8 mg L −1 concentration reported by Lentz and Westermann (2010) in runoff from a recently manured Portneuf soil. In the Lentz and Westermann (2010) study, (i) the manure had been incorporated into dry soil (water contents < 0.05 g g −1 ) just 2 wk before the irrigation, and (ii) little or no microbial activity or leaching had occurred in the manured soil before the irrigation. Thus, water soluble C concentrations in their manured soil were high.…”

“…Similarly, researchers have studied DOC losses in drainage water, tile-drain, and runoff from grassland soils and corn or hay fields, but did not consider other C-budget components (Don and Schulze, 2008;Royer et al, 2007). Other studies have examined the DOC loadings in surface water inflows and runoff for furrow-or flood-irrigated fields, but did not compare untreated soils with manured soils or measure other C inputs and outputs (Poch et al, 2006;King et al, 2009;Lentz and Westermann, 2010;Mailapalli et al, 2010;Ruark et al, 2010;Krupa et al, 2012).…”

Nutrient loads and sediment losses in sprinkler irrigation runoff affected by compost and manure

“…Manure applications are thought to increase the potential for nutrient losses in surface irrigation runoff (Lentz and Westermann 2010). Our findings, however, revealed that the losses of NO 3 -N, NH 4 -N, TP, and FeO P in sprinkler irrigation runoff did not differ for two years between unamended soils and soils into which manure had been applied, then incorporated (table 6).…”

“…They found greater TP, DRP, and NH 4 -N concentrations and greater DRP loads in runoff from manure rather than compost plots after amendments were applied for two consecutive years. By delaying irrigation until the spring, one can greatly reduce sediment and nutrient losses in surface irrigation runoff from fields that received manure the preceding fall (Lentz and Westermann 2010). Potassium (K) in runoff is of little environmental concern except when the K is associated with certain anions that increase the salt loading to receiving water bodies.…”

“…Thus, runoff constituent concentrations reflect only changes resulting from the treatments themselves. All runoff constituent concentrations and corresponding flume flow rates were integrated with time using the computer program WASHOUT (Lentz and Sojka 1995;Lentz and Westermann 2010) to report loads as constituent mass per unit area per unit gross water applied, thus normalizing the measured nutrient loads by the irrigation water applied.…”