Nitrogen (N) fertilization can be an effective way of increasing forage production. The question is how much does N fertilization increase forage yield of western wheatgrass (Agropyron smithii) when there is not a shift in species composition as occurs when N is applied to a native range site. The objectives of this research were to determine the residual effects of a single application of (1) 6 geometric rates of N and phosphorus (P) on forage yield, in vitro dry matter digestibility (IVDMD), crude protein (CP), and phosphorus (P) concentration (conc) of western wheatgrass grown near Sidney, Mont. during a 10-year period. Ammonium nitrate was applied at 0, 40, 80, 160, 320, and 640 kg N/ha in March 1973 and triple super phosphate at 45 kg P/ha on split plots during August 1975. A single application of N increased forage yield by 0.0, 0.0, 0.95, 0.35, 0.0, 1.16, 0.52, and 1.41 kg/ha per kg of N applied the 1st, 2nd, 3rd, 4th, 5th, 6th, 7th, and 10th year sampled, respectively, regardless of N rate. Nitrogen fertilization increased the accumulative forage (P<0.01) and CP (P<0.01) yield over the 8 harvest-years by 4.35 and 0.87 kg/ha per kg of N applied. Nitrogen fertilization increased the average forage IVDMD by 0.1 percentage units (P<0.05) and decreased P conc by 0.03 percentage units per 100 kg N/ha applied (P<0.01). Application of 45 kg P/ha in 1975 increased the P conc of the forage an average of 0.04 percentage units each year, increased forage yield only the 10th year by 150 kg/ha, and had no effect on IVDMD or CP. This study also showed that long-term observations are necessary to measure the residual effects of fertilization. This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries. The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact lbry-journals@email.arizona.edu for further information. Migrated from OJS platform August 2020
Scholarly peer-reviewed articles published by the Society for Range Management. Access articles on a rolling-window basis from vol. 1, 1948 up to 5 years from the current year. Formerly Journal of Range Management (JRM). More recent content is available by subscription from SRM.