Potential of Cool‐Season Species as Cover Crops and Forage in the Southeastern United States
2018
Han, K.J. | Smith, D. J. | Pitman, W.D.
CORE IDEAS: Productivity of cool‐season cover crops depends on seasonal weather conditions. The annual grasses can produce substantial regrowth following winter harvest. Optimized growth termination justifies dual‐purpose plantings of cool‐season annuals. Cool‐season annuals can provide nutritious forage from late winter to early spring in addition to contributing soil conservation benefits during the winter season in the lower southern states. This application may reduce the direct input cost coming from adopting a winter cover crop in row crop production. A 2‐year field trial was conducted to determine the relative early‐season forage value of a variety of crops when planted for combined purposes of forage production and winter cover crops. The eight cover crop treatments included seven monocultures—annual ryegrass (Lolium multiflorum), cereal rye (Secale cereal), oats (Avena sativa), triticale (Triticale hexaploide), radish (Raphanus sativus), hairy vetch (Vicia villosa), and crimson clover (Trifolium incarnatum)—and a mixture of annual ryegrass/crimson clover/radish. Two harvests were made each year considering potential crop rotation. The dry matter (DM) yield ranged across cool‐season annual crop treatments from 1478 lb/acre for crimson clover in 2016 to 3983 lb/acre for oats in 2015. Delayed fall planting due to excessive rainfall in 2015 reduced DM yields and delayed growth for an initial harvest by almost 3 weeks compared with the first year. All treatments produced highly digestible forage, based on in vitro true digestibility (IVTD) analysis, ranging from 71–92%. As the growing season advanced, acid detergent fiber (ADF) in triticale increased at the greatest rate among the tested cover crops. Crude protein (CP) decreased more than 7 percentage points between harvests in the grasses and radish while CP response of legumes was not consistent between years. Dual‐purpose plantings of oats or an early maturing annual legume for combined cover crop contributions and forage production appear particularly appropriate for cropping systems with no‐till April planting into grazed‐out cover crop stubble.
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