March 15, 2012

Some Great Plains alfalfa growers periodically cultivate their alfalfa stands, often using a spring-tooth harrow, disk or other specialized tillage equipment. Usually it's done to control weeds like mustards and downy brome, but sometimes light tillage is used to incorporate fertilizer, smooth rough spots, or lessen compaction. Some growers claim this tillage increases production by splitting crowns into two or more plants.

Are these claims true, or just old alfalfa grower’s tales? Tillage generally does stimulate early alfalfa growth by blackening the soil; however, most research shows that if spring tillage is aggressive enough to provide useful weed control, it also damages alfalfa stands and yields. Likewise, light tillage that does not harm stands usually fails to control many weeds. Apparently, you can’t have your cake and eat it, too.

Tillage may create other problems. By cutting open some of the crowns, diseases can enter and injure the plant. These crown and root diseases usually take a while to show much damage, so if the field will be rotated to another crop in a year or two, losses will be slight if any. But, if you want to keep that stand for a longer time, do not till or diseases might start to thin your stands earlier than normal.

If spring tillage occurs before alfalfa greens up and when soils are dry, it does little harm to alfalfa, but also provides little good. 

Bruce Anderson
Extension Forage Specialist