Rotational Benefit of Ryegrass.

Several studies have shown a non-nitrogen based yield increase of crops in rotation with legumes. This is considered to be a “Rotational Benefit.” This study was conducted to determine if a rotational benefit existed for grasses included in rotation with corn (Zea mays L.). Replicated plots of corn (Zea mays L.) DeKalb DKC50-20 at 74,000 plants ha^-1, Italian ryegrass (Lolium multiflorum L): Green Spirit mixture (65% Barextra and 35% Bardelta) at 28 mg ha^-1, and alfalfa (Medicago sativa L) Pioneer 55V48 at 22 mg ha^-1 were established on the University of Wisconsin Arlington Agricultural Research Station (43.30°N, 89.35°W) on a Plano silt loam (fine-silty, mixed, superactive, mesic Typic Argiudoll) and harvested in the each seeding year.  Perennials were killed in the fall, plots were tilled the next spring and corn planted.  Corn following corn was fertilized with 224 kg N ha^-1 the second year and corn following other crops received 112 kg N ha^-1.  Averaged over 2 years, corn yielded 26.3% less total dry matter the year following corn.  Corn following alfalfa yielded 17% more total dry matter than corn following corn which indicated a rotational benefit as previously reported. Corn following Italian ryegrass had the highest yields producing 22 to 25% more than corn following corn.

This research was partially supported by Barenbrug USA.

Table 2. Total dry matter yield of corn following differing previous year crops
	Corn Silage Yield (mg ha-1)z
Previous Crop	Harvest Year		Average Increase (%)
	2008	2009
Corn	17.0	17.5	0
Alfalfa	19.5	20.8	17
Italian ryegrass 25-day harvest schedule	20.4	22.9	25
Italian ryegrass 35-day harvest schedule	19.3	22.9	22
LSD 5%	1.8	0.5