– Mark Sulc, Extension Forage Specialist, The Ohio State University
If you have planted cover crops and plan to graze, ensile, or make hay out of them to feed to livestock, you should consider the potential for nitrate toxicity in the forage this year. This could be especially of concern for cover crops planted after corn silage that was stunted by drought and received a good dose of N fertilizer earlier this year. Nitrates can accumulate in about any cover crop, including oat, cereal rye, annual ryegrass, and brassica species. If there is potential for N carryover in fields where you planted cover crops, or if N fertilizer was applied to the cover crop forage, it is advisable to test the forage for nitrate content before you harvest or graze the forage this fall. Recent rains could have promoted a flush of nitrates to be taken up by the plant. To make matters worse, the current cold snap might shut down plant growth (depending on the cover crop species) preventing further accumulation of yield, so high nitrate concentrations will not be diluted out in the plant. So consider the N carryover situation in your fields, and test your cover crop forage accordingly.