Late-summer forage on prairie sandreed dominated rangeland after spring defoliation.

Abstract

The potential of using spring defoliation to improve late-summer nutritive value of prairie sandreed [Calamovilfa longifolia (Hook.) Scribn.] on rangeland was studied with a factorial array of replicated 1-year treatments that included clipping plots at ground level or at a 5 or 10 cm height on 1 April, 26 April, 20 May, or 14 June. Vegetative tillers accounted for 83% of prairie sandreed herbage on unclipped control plots. After spring treatments, late-summer crude protein content (CP) in vegetative tillers of prairie sandreed ranged from 5.0 to 7.9% and in vitro dry matter digestibility (IVDMD) ranged from 45 to 52% compared to 5.0% CP and 45% IVDMD for unclipped plots. Reductions in mean weight of prairie sandreed vegetative tillers after April and May treatments were offset by 20 to 30% increases in tiller density. Treatments that increased tiller density had little or no effect on forage nutritive value when applied more than 90 days before herbage was sampled. Nutritive value of prairie sandreed and total yield from all species in mid-September were unchanged after April treatments. After sandreed tillers began to emerge in early May, late-summer nutritive value improved as clipping was delayed and degree of defoliation increased during May and June, however, yield was inversely related to nutritive value. While mid-September nutritive value of prairie sandreed was comparable to mid-summer values after June treatments, clipping reduced projected, late-summer stocking rates by 58 to 100% compared to control. It may be possible to improve mid-September forage nutritive value with moderate stocking rates in June with less reduction of total late-summer herbage because of selective herbivory. Measurable increases in prairie sandreed yield after complete defoliation of associated species in late April indicated prairie sandreed populations might be increased by concentrating cattle in selected pastures during late April.