Effects of cutting height on shoot regrowth and forage yield of alfalfa (Medicago sativa L.) in a short-term cultivation system

Alfalfa (Medicago sativa L.) has been cultivated increasingly widely in the arable area of the middle-eastern regions of China as a short-term (1 or 2years) component of a forage-grain rotation system, but little is known about the harvesting technique for this legume in the short-term rotation. This study investigated the effects of cutting height (0-, 5- and 10-cm stubble height above the soil surface) on shoot regrowth and forage yield of alfalfa in the second-year growing season at two sites in Shandong Province, China. Forage yield at the first harvest was higher under lower cutting height (0>5>10cm) at both sites due to greater length and weight of individual shoots harvested. At the site where plants were fertilized and irrigated after the first harvest, lower cutting height increased the number of buds during the early regrowth period and the number of shoots per plant at the second harvest, though it decreased the length and weight of individual shoots harvested. At the site without fertilizer and irrigation, lower cutting height delayed the sprouting of buds after defoliation, and decreased the length of shoots harvested at the second cut. Forage yield at the second harvest was ranked 0 approximate to 5>10cm under fertilizer and irrigation, and 0 approximate to 5 approximate to 10cm under no fertilizer and irrigation. The path analysis showed that forage yield was affected primarily by the weight of individual shoots at the first cut and by shoot number per plant in the aftermath. Harvesting close to the ground is considered to be a management option to increase alfalfa yield in a short-term forage production system subjected to irrigation and fertilizer.