Recently the Midwestern US has seen a push has seen a movement to improve water quality for waters eventually reaching the Gulf of Mexico; this is in an effort to reduce the hypoxic zone. Cover crops show effectiveness at reducing nitrogen and phosphorus loads in waters leaving fields. One concern with cover crops is their impact on grain production following the kill of the over crop as they tend to tie nutrients into organic forms, which are not immediately plant available. This study looked to identify if manure would act differently than a commercial fertilizer (urea) when interacting with a cover crop (cereal rye).

This study found that cereal rye was effective at reducing total nitrogen and nitrate that leached from soil columns treated with both manure and urea, with no significant difference by fertilizer source. The cereal rye produced 20% more biomass when a surface application of urea was used instead of injected manure, however the cereal rye’s nitrogen uptake per acre was similar and phosphorous uptake was higher when manure was applied. No differences were found in soil nutrient levels regardless of cover crop status or fertilizer source. In terms of corn production cereal rye inhibited yields with both urea and manure as the nutrient source. There was no significant difference by nutrient source in terms of corm yield, however manure produced nominally higher yields. Overall, during the 2015-2016 season, there was no significant differences in how the manure and urea interacted with the cover crop.