Managing Roundup Ready� Alfalfa Interseeded Into a Bermudagrass Stand in Mississippi.

Alfalfa is well adapted in many hay systems across the United States and has persisted in grazing situations under adequate rainfall and well-drained soils. In high precipitation regions like the southeastern U.S., lack of moisture is usually not a limitation in forage systems which coupled with mild winters can prolong the grazing season. �In Mississippi, fertility issues often decrease profits of forage systems because of the high input needed to maintain quality hay and pastures of warm-season perennial grasses such as bermudagrass. Roundup Ready^� alfalfa can possibly be interseeded into existing pastures and consequently prolong the growing season and improve forage quality with minimum fertility input. The study was a split-split plot design replicated 4 times.� Main plots were two tillage systems (minimum tillage and no-tillage), subplots were variety x seeding rate and sub-subplots were herbicide treatments (glyphosate or no herbicide). Two Roundup Ready^� alfalfa varieties DKA41-18RR and DKA65-10RR were planted at a rate of 17, 22, 28 and 39 kg ha^-1 in the fall of 2011. Sup-subplots receiving the herbicide treatment were sprayed with glyphosate at a rate of 0.6 L ha^-1. Potash was applied according to the soil with no other fertility adjustments or nitrogen applications. The April harvest was significantly affected by seeding rates with 39 and 28 Kg ha^-1 producing the greatest forage yields; however the May and August harvests were not affected. The two higher seeding rates had a 6% increase in seasonal yield but not significant that the other rates.� Alfalfa composition in the stand was greatest at the 39 kg ha^-1 seeding rate and lower at the 17 kg ha^-1.� Percent alfalfa in the stand decreased up to 41% between the May and August harvest. �After April, bermudagrass contributed to more uniform forage yields in the lower alfalfa seeding rates.