Improving the Ecology of Corn Production and Testing Perennial Alternatives to Silage Corn
Establishment of cover crops in corn can lead to reductions of soil erosion, soil nitrate losses, and
maintenance soil organic matter. Little is known about using cover crops in corn, nor what kinds
of hybrids and populations are best suited to its management.
1) To optimize corn/cover crop systems and to evaluate the effects on corn yields, soil structure
and yields of subsequent crops.
2) To optimize management of green-manure cover crops for conventional-till and ridge-till corn
3) To test high yielding perennial forages and polycutures as alternatives to silage corn.
Cover crops (hairy vetch and annual ryegrass) were seeded into corn after last cultivation for
experiments conducted in Illinois, Ohio, Nebraska, and Wisconsin. The use of cover crops was
tested in eight hybrids at two different seeding rates, and also as test strips on farmers' fields and
in trials with silage and grain corn. Plots with cup-plant, a mesic prairie plant native to the
Midwest, and other promising perennial polycultures were established.
Cover crop yields ranged from 0 to 3,247 lbs of dry matter/acre in the fall. High corn populations
and high yields appeared to have negative impacts on the yield of the cover crop. However,
establishment of the cover crop appeared to be a critical factor. Establishment was successful
where cover crops were drilled but seldom successful where cover crops were broadcast. The use
of cover crops on one site (a biodynamic farm) increased grain yields of a companion corn crop 5
percent in one year and 8 percent in the second year. There were no yield responses on the other
sites. Oats grain yields were 16 percent higher where cover crops were grown in corn the
previous years than where they were not grown. Cover crops appeared to suppress quack grass
and broadleaf weeds on one site.
Multi-eared (prolific) corn hybrids appeared to be beneficial to the yield of the cover crop, but
only under conditions in which they could express their prolificacy. The tops of the prolific corn
hybrids appeared to break off above the ear then they expressed prolificacy, allowing more light
to the cover crop, and this might explain the relationship. Through cutting corn early for silage
improved the yields of the cover crop, upright leaved hybrids did not have the highest cover crop
Studies with different methods for controlling sweet clover before planting corn showed that
incorporating the green manure was crucial in order to obtain full benefits. Mow/silt-till and
ridge-till systems produced negative effects, and relationships were unable to be correlated with
soil moisture contents at planting. Experiments with cup-plant indicated that it has potential for
use as a silage crop to replace corn on wetter soils. Yields were similar to corn and it had a
quality similar to alfalfa.
Areas Needing Further Study:
In order to recommend these practices to farmers, more work is necessary to determine a precise
date of seeding the cover crop, type of cultivator attachments for seeding, and to gain more
information on the effects of the cover crops on corn and subsequent crops.