Response of established forages on reclaimed mined land to fertilizer N and P

A field study was conducted from 1981 through 1986 on an established stand of grass and legume species on topsoiled coalmine spoils in northwest Colorado to evaluate the effects of N and P fertilization on dry matter production, species composition, canopy cover, and forage crude protein and P concentrations. Fertilizer treatments included annual fall applications in 1981 through 1985 of: 0, 28, 56, 112, and 224 kg N ha-1; 56 kg P ha-1; and 112 kg N ha-1 + 56 kg P ha-1. Additionally, single fall applications of N were applied in 1981 through 1983 at rates of 0, 28, 56, 112, 224, and 448 kg N ha-1 to other plots that had not been previously fertilized. Plots were harvested at grass anthesis in 1982 through 1986. Fertilizer P significantly increased forage P concentration but did not significantly affect yield, crude protein concentration, or species composition. Fertilizer N did not significantly affect species composition or forage P concentration but did significantly increase dry matter production and crude protein concentration with increased N rate. Averaged over the 5 years of the study, annual application of 28, 56, 112, and 224 kg N ha-1 increased herbage production by 23, 19, 19, and 11 kg per kg N applied, respectively. On those plots receiving a single application of fertilizer N, significant increases in dry matter production with increased N rate were noted only during the first growing season after N fertilization. Significant yield response to carry-over fertilizer N was noted in the second (and occasionally third) growing seasons only at the 448 kg N ha-1 rate. The data indicate that annual applications of fertilizer N would be more effective than infrequent applications of high rates of N on these reclaimed mined lands.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 202