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Cicer Milkvetch and Alfalfa as Influenced by Two Cutting Schedules

Gabrielsen, B. C., Smith, D. H., Townsend, C. E.
Agronomy journal 1985 v.77 no.3 pp. 416-422
Astragalus cicer, Medicago sativa, harvest date, forage crops, yields, protein composition, Colorado
Cicer milkvetch (Astragalus cicer L.) is a promising forage legume, but little is known about its response to cutting. A 2-year study was conducted at Fort Collins, CO, on a Nunn clay loam (fine, montmorillonitic, mesic Aridic Argiustoll) soil to compare yield, quality, and trends in carbohydrate reserves of cicer milkvetch and alfalfa (Medicago sativa L.) in response to annual three- and four-cut clipping treatments. Quality was evaluated by determining concentrations of crude protein (CP) and cell wall constituents (CWC) in herbage from each harvest. Seasonal dry matter yields of alfalfa were similar under both clipping treatments during each year. Yields of cicer milkvetch were reduced under the more frequent cutting schedule in 1979, but not in 1980. During 1979, quality differences between the clipping treatments were apparent for alfalfa but not for cicer milkvetch. Improved quality, as measured by increased CP and decreased CWC concentrations, was observed in herbage from both species under the more frequent clipping treatment in 1980. Herbage CP concentration was simiilar under comparable clipping treatments during both years, however, the CWC concentration of cicer milkvetch was consistently lower than that of alfalfa. Cyclic trends in carbohydrate reserves were observed in alfalfa under both clipping treatments in 1980, but only under the three-cut treatment in 1979. Carbohydrate reserve trends in cicer milkvetch roots and rhizomes were less cyclic than in alfalfa and similar under both cutting schedules each year. Carbohydrate reserve concentrations in all forage entries were similar at the end of the 1980 growing season regardless of clipping treatment. Following cutting, carbohydrate reserves in alfalfa were readily utilized during the initial period of recovery. Carbohydrate reserves in cicer milkvetch appeared to be actively involved in regrowth processes only when little, or no, residual leaf area remained after cutting.