Dry matter yield and chemical composition of alfalfa (Medicago sativa L.) under a four-cut system
Abstract
Alfalfa (Medicago sativa L.) is the most used forage legume in northern U.S.A. Although many studies have been carried out to determine the proper harvest management to obtain the most profitable yields of high quality forage, there is still a lack of scientific data for predicting the behavior of dry matter yield and quality parameters during the year. The objectives of this study were to determine the dry matter yield and chemical composition of alfalfa harvested for the first time after winter and three through twelve weeks after each of three cuttings during two growing seasons. Alfalfa cv. Tempo and Classic were grown in mixture on a Warsaw sandy loam soil in West Lafayette, Indiana, and sampled weekly over a 10-week period at each of four cuttings, starting with three weeks of regrowth except for the first cutting during two growing seasons. Harvesting alfalfa in late spring resulted in the highest dry matter yield. There was a trend to increase DM yield with increasing age of the crop at all of the cuttings. Crude protein concentration decreased from 25 to 13% with advance in crop age except at the fourth cutting, in early and mid-fall, when the two-year average ranged from 22 to 18%. A depletion and replacement pattern of total nonstructural carbohydrates in the roots were observed. Neutral detergent fiber, acid detergent fiber and cellulose tended to increase with age of plants. The lowest concentration of these variables were found at the third cutting during mid and late summer. At the first cutting phosphorus, potassium, magnesium, copper, and zinc concentration increased with crop age, calcium was variable, boron and sodium had no definite trend. At the following cuttings for almost all of minerals there was a trend to decrease with aging, except at the third cutting when phosphorus, potassium, magnesium, boron, copper and zinc changed slightly. By utilizing the data obtained in this study and the nutritional requirements of his animal production system, a farmer can determine the proper time to harvest alfalfa under a 4-cut system.
Degree
Ph.D.
Advisors
Rhykerd, Purdue University.
Subject Area
Agronomy
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