Yield and Quality of Cicer Milkvetch Forage as Influenced by Cutting Frequency

Cicer milkvetch (Astragalus cicer L.) is a potentially valuable forage crop for irrigated pastures, but little information is available concerning the effects of management practices on forage production. Therefore, the objective of this field study was to evaluate the effect of six harvest treatments on yield, forage quality, weed invasion, and persistence of stand. The study was conducted under irrigation on a Nunn clay loam soil (aridic Argiustoll). The treatments consisted of clipping the forage two, three, four, five, six, and seven times annually for 3 years to a height of 7.5 cm. Forage yields and weed counts were taken for 3 years, and seven quality factors and four mineral elements were evaluated for 2 years. Total nonstructural carbohydrates in the rhizomes were measured at the end of the 3rd harvest year. There were significant differences in yield among harvest treatments in 2 of 3 years and for the 3-year average. In general, the two- and three-cut treatments were the most productive with 3-year average yields of 10.5 and 10.7 metric tons/ha, respectively. Considerably more weeds were present in the five-, six-, and seven-cut treatments than in the two-, three-, and four-cut treatments. Annual weeds were most prevalent during the first 2 years, but by the 3rd year dandeloins (Taraxacum spp.) were the most common. Although there were significant differences among treatments for total nonstructural carbohydrates in the rhizomes, the differences were not associated with persistence because persistence of stands was excellent for all treatments. In vitro dry matter digestibility (IVDMD) and all chemical constituents evaluated, with the exception of magnesium and potassium, differed significantly among treatments each year. In general, cell wall constituents (CWC) and cellulose decreased with an increase in the frequency of cutting. Protein, IVDMD, and phosphorus increased as the number of cuttings increased. Lignin, hemicellulose, silica, calcium, magnesium, and potassium varied among cutting treatments. The quality of cicer milkvetch forage was high for all cutting treatments. Based on yield, quality, and stand persistence cicer milkvetch has the attributes of a desirable forage species.