Controlling Nitrate Leaching in Irrigated Agriculture

Abstract

The impact of improved irrigation and nutrient practices on ground water quality was assessed at the Nebraska Management System Evaluation Area using ground water quality data collected from 16 depths at 31 strategically located multilevel samplers three times annually from 1991 to 1996. The site was sectioned into four 13.4‐ha management fields: (i) a conventional furrow‐irrigated corn (Zea mays L.) field; (ii) a surge‐irrigated corn field, which received 60% less water and 31% less N fertilizer than the conventional field; (iii) a center pivot‐irrigated corn field, which received 66% less water and 37% less N fertilizer than the conventional field; and (iv) a center pivot‐irrigated alfalfa (Medicago sativa L.) field. Dating (3H/3He) indicated that the uppermost ground water was <1 to 2 yr old and that the aquifer water was stratified with the deepest water ∼20 yr old. Recharge during the wet growing season in 1993 reduced the average NO3–N concentration in the top 3 m 20 mg L−1, effectively diluting and replacing the NO3‐contaminated water. Nitrate concentrations in the shallow zone of the aquifer increased with depth to water. Beneath the conventional and surge‐irrigated fields, shallow ground water concentrations returned to the initial 30 mg NO3–N L−1 level by fall 1995; however, beneath the center pivot‐irrigated corn field, concentrations remained at ∼13 mg NO3–N L−1 until fall 1996. A combination of sprinkler irrigation and N fertigation significantly reduced N leaching with only minor reductions (6%) in crop yield.

Irrigation management, nitrogen fertilization and nitrogen losses in the return flows of La Violada irrigation district (Spain)

“…The lower ICUC values in the 90s than in the 00s were due to the already indicated changes in irrigation infrastructures and management. Hence, as found in other studies (Bonati and Borin, 2010;Cavero et al, 2011;Spalding et al, 2001), a key strategy to reduce N export loads is the improvement of irrigation performance. In the case of VID, each 10% increase in ICUC, above 40% ICUC, will decrease N export loads by 31 kg N/ha (Figure 5c).…”

Nonpoint source groundwater pollution and endogenous regulatory policies

“…This suggests that a switch to sprinkler irrigation can be used to achieve regulatory compliance with no further interdiction required. These results confirm those of Spalding et al [2001]; on Nebraska test plots they found that sprinkler irrigation reduced nitrates in groundwater and could be used to maintain nitrate levels at 10 ppm. Furrow irrigated fields, by comparison, required more irrigation water, more nitrogen fertilizer, and increased groundwater nitrogen levels.…”

Groundwater Quality and Nitrogen Use Efficiency in Nebraska's Central Platte River Valley

“…This supports recommendations from previous detailed research efforts as part of the USDA Management Systems Evaluation Area project, which had a study site within the CPNRD-GWMA from 1990 to 1996. In the Management Systems Evaluation Area project, Spalding et al (2001) found that a combination of conversion from furrow to sprinkler irrigation, accompanied with N fertigation, significantly reduced N leaching. As part of the Conservation Effects Assessment Project evaluation, a survey was conducted in 2008 of producers in CPNRD-GWMA Phase 1, 2, and 3 areas to evaluate their current use of certain practices.…”