Irrigated Mountain Meadow Fertilizer Application Timing Effects on Overland Flow Water Quality

• Published in: Journal of environmental quality 2003-09, Vol.32 (5), p.1802-1808
• Main Authors: White, Shawn K, Brummer, Joe E, Leininger, Wayne C, Frasier, Gary W, Waskom, Reagan M, Bauder, Troy A
• Format: Article
• Language: English
• Subjects: Agricultural pollution; Agricultural runoff; Agriculture; Agronomy. Soil science and plant productions; Altitude; Ammonium; ammonium nitrogen; application timing; Applied sciences; autumn; Biological and medical sciences; Colorado; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental impact; Exact sciences and technology; Fertilizer application; Fertilizers - analysis; Fundamental and applied biological sciences. Psychology; grasslands; irrigated farming; losses from soil; Meadows; monoammonium phosphate; Natural water pollution; Nitrogen - analysis; Nonpoint source pollution; NPK fertilizers; Overland flow; phosphorus; Phosphorus - analysis; Pollution; Pollution, environment geology; Rainwaters, run off water and others; Return flow; Soil and water pollution; Soil science; spring; Time Factors; Water Pollutants, Chemical - analysis; Water pollution; Water Pollution - prevention & control; Water quality; Water treatment and pollution; Waterways
• ISSN: 1537-2537; 0047-2425; 1537-2537
• DOI: 10.2134/jeq2003.1802

Nonpoint-source pollution from agricultural activities is currently the leading cause of degradation of waterways in the United States. Applying best management practices to flood-irrigated mountain meadows may improve agricultural runoff and return flow water quality. Prior research has focused on fertilizer use for increased hay yields, while few studies have investigated the environmental implications of this practice. We examined the effects of fertilizer application timing on overland flow water quality from an irrigated mountain meadow near Gunnison, Colorado. Application of 40 kg phosphorus (P) and 19 kg nitrogen (N) ha−1 using monoammonium phosphate (11–52–0, N–P–K) fertilizer to plots in the fall significantly reduced concentrations of reactive P and ammonium N in irrigation overland flow compared with early or late spring fertilization. Reactive P loading was 9 to almost 16 times greater when fertilizer was applied in the early or late spring, respectively, compared with in the fall. Ammonium N followed a similar trend with early spring loading more than 18 times greater and late spring loading more than 34 times greater than loads from fall-fertilized plots. Losses of 45% of the applied P and more than 17% of the N were measured in runoff when fertilizer was applied in the late spring. These results, coupled with those from previous studies, suggest that mountain meadow hay producers should apply fertilizer in the fall, especially P-based fertilizers, to improve hay yields, avoid economic losses from loss of applied fertilizers, and reduce the potential for impacts to water quality.