Defoliation Regime Effects on Accumulated Season‐long Herbage Yield and Quality in Boreal Grassland

Abstract

Within boreal grasslands, little information exists on the effects of initial defoliation date, frequency, and intensity on accumulated herbage yield and quality. We investigated the effects of initial defoliation in May, June or July, at heights of 5, 10 or 15 cm, and repeated at 2-, 4-or 6-week intervals throughout the growing season. Harvested material was combined with year-end residual biomass, and examined for herbage removed, crude protein (CP), crude protein yield (CPY) and neutral detergent fibre (NDF). Compared to single defoliated check plots, total, grass and forb dry matter (DM) yields were lower under repeated defoliation by 25, 38 and 17 %, respectively. The majority of total herbage produced was harvested in the spring clipping. Total, grass and forb DM yields peaked under moderate (10 cm) clipping. Total DM and grass biomass were maximized with long (6 week) recovery periods. In contrast, forb biomass was greatest with May defoliation followed by a 4-week interval. While maximum grass CPY was found under 10-cm defoliation, forb CPY peaked with early and moderate to intensive defoliation. These results indicate that season-long herbage biomass, along with CPY, can be maximized in boreal grasslands through controlled defoliation.

Effect of summer grazing on forage quality of woody and herbaceous species in a silvopastoral system in northern Greece

“…Mature and dry herbage yield in early June contained high levels of NDF (Donkor et al, 2003). Generally, the nutritive value and the IVOMD of herbage were slightly increased by repeated short-duration summer grazing.…”

Effects of cattle grazing on herbage quality in a herbaceous Mediterranean rangeland

“…, 2008). Studies that evaluated the effects of cutting treatments on the nutritive value of herbage showed that defoliation produced forage of relatively good and higher quality (Donkor et al. , 2003; De Santis et al.…”

Divergent effects of defoliation intensity and frequency on tiller growth and production dynamics of Pascopyrum smithii and Hesperostipa comata

“…RS with repeated grazing in a growing season is based on the premise that pasture regrazing would be beneficial if defoliation stimulates compensatory plant responses (McNaughton, ). Indeed, grazing does not universally compromise grass productivity (e.g., De Bruijn & Bork, ; De Bruijn, Bork, & Grekul, ; Donkor, Bork, & Hudson, , ) and may maximize the latter at some optimal frequency and intensity (Turner, Seastedt, & Dyer, ). A recent investigation in the Mixed Grass prairie of western Canada suggests that high‐intensity–low‐frequency defoliation may lead to greater production than areas exposed to high‐intensity–high‐frequency defoliation, although both remained lower than areas where defoliation was deferred to the end of the growing season (Bork, Broadbent, & Willms, ).…”