Yield and Quality of Alfalfa Harvested During Autumn and Winter and Harvest Effects on the Spring Crop1

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Abstract
The production of pasturage is insufficient to meet the needs of grazing animals during autumn in mid‐latitude states of the eastern U.S. The possibility for use of perennial forage legumes after frost has not been studied.The object of this experiment was to gain information concerning the yield and quality during autumn and winter of alfalfa (Medicago sativa L.) produced during late summer and early autumn and to determine the effects of such harvests on spring growth and yield.In replicated field plot experiments, we measured alfalfa yield, forage quality, root reserves and spring growth for two seasons. Stockpiling periods started in early August and early September with an array of harvests during autumn and winter.Two‐year average yields were 1,520 and 892 kg/ha on 1 November for growth made from early August and early September, respectively. The loss of a potential hay harvest must be considered when August stockpiling is contemplated. Forage quality declined during autumn due largely to leaf drop and stem death. On 1 November, alfalfa stockpiled from early August was significantly lower in leaf percentage, N and P concentration, and in vitro dry matter disappearance (IVDMD) than that stockpiled from early September. Forage IVDMD decreased from 59.1% to 45.4% between 15 October and 15 November for alfalfa stockpiled from early August but remained about the same, 69.9 to 70.0 for alfalfa stockpiled from early September. Crude protein (CP) generally and Ca always exceeded beef cow requirements while P and Mg concentrations declined below requirements regardless of stockpiling period. Supplementation of energy, P, and Mg would be necessary during late autumn and winter. Harvests on or after 1 November generally did not reduce root carbohydrate reserves and, with one exception, did not reduce first harvest yield in the following year, indicating that grazing or clipping could occur after that date at this location.Acceptable yields of quality forage were produced during a 6 week or longer period in late summer and autumn. This forage could be utilized by mid‐November with little reduction of the following spring crop.

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