Fall Harvest Management of Alfalfa in the Southern Plains1

Abstract

AbstractFall regrowth of alfalfa (Medicago sativa L.) frequently is harvested for hay in the southern plains. Possible detrimental effects of harvesting from mid‐September to late November have not been studied. The objective of this research was to determine the effects of fall cutting dates on root total nonstructural carbohydrate (TNC) concentrations, productivity, and stand persistence of semi‐dormant, dryland alfalfa in the southern plains. From 1978 to 1980, five fall cutting date treatments were imposed on a 4‐year‐old stand of ‘Kanza’ and 2‐year‐old stands of ‘Arc’ and ‘Liberty’ alfalfas grown under dryland conditions on a fine, mixed thermic, Pachic Arguistolls (McClain silt loam). Three harvests per season were made at 10 to 25% bloom prior to the fall cutting date treatments which were made at fourth harvest of the season. Root carbohydrate analyses were made on roots dug 7 December of each year. Forage yields were taken during each growing season subsequent to fall cutting date treatments with a residual harvest taken in April 1981. Stand densities were determined at initiation of the study in 1978 and each fall thereafter. Final stand densities were determined in May 1981. Only forage yields were determined for Liberty. Fall cutting date treatments had little effect on root carbohydrate reserves. Roots dug in 1978 had higher TNC percentages than those dug in 1979 or 1980; however, fall cutting date treatments significantly influenced TNC concentrations only in the fall of 1979. Fall cutting date treatments had a greater effect on first harvest in the subsequent spring than on total yields. Total yields for each season and total yields over the duration of the study for each cultivar indicate that harvesting could take place at any fall date with little effect on productivity in subsequent years. Stands of all cultivars declined over the course of study and at the conclusion of the study in May, 1981 there were no differences in stand persistence that could be attributed to fall cutting date treatments.