Submitted to: Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: December 16, 2013
Publication Date: January 15, 2014
Citation: Grabber, J.H. 2014. Alfalfa, clovers, and grasses as companion crops for silage corn. In: Proceedings of 2014 Wisconsin Crop Management Conference, 14-16 January 2014, Madison Wisconsin. p. 82-85. Technical Abstract: Corn silage is commonly fed to dairy cattle and other types of ruminant livestock, but its production can leave cropland vulnerable to nitrate leaching and runoff of nutrients and sediment. In a four-year Wisconsin study, we evaluated forage yields from manured rotations of corn grown with kura clover living mulch or interseeded red clover followed by a year of clover production and from manured continuous corn grown with interseeded Italian ryegrass, fall-seeded winter rye, or no companion. The corn-interseeded red clover system produced the highest and most stable yields of silage corn across years and often the highest clover yields. Manured continuous corn grown with or without annual grass companion crops usually produced greater overall dry matter yields than corn-clover rotations, but crude protein yields of rotations exceeded continuous corn treatments. Unlike other cropping systems we examined, yields of corn grown with grasses were sensitive to the timing of manure application; fall manure promoted higher yields with ryegrass while spring manure favored higher yields with rye. Yields of continuous corn systems and of corn grown rotationally with kura clover declined as the study progressed, due in part to increasing weed pressure. In a second study, we evaluated the use of prohexadione-calcium for enhancing the establishment of alfalfa interseeded into silage corn and for boosting forage yields of alfalfa during the following production year. Prohexadione sprayed in June with drop nozzles at 10 to 14 oz ai/A typically reduced alfalfa top growth by about 20% in July and doubled or tripled alfalfa seedling stand density by mid-October compared to non-treated controls. First-year yields of alfalfa established the previous year by interseeding were two-fold greater than alfalfa conventionally spring-seeded after corn. Prior year prohexadione applications increased first year alfalfa yields by about 12% and fall stand densities by 37 to 130% compared to untreated interseeded controls. Alfalfa interseeding reduced silage corn yields by about 7% and prohexadione application had no effect on corn yields. Additional studies with prohexadione and other plant growth regulators are needed to find ways of lessening yield reductions in corn and to develop workable production systems for farms.