In Corn Silage Farmers in the driest parts of Ohio and Indiana need to be careful about the accumulation of toxic levels of nitrates in corn harvested for silage, say Ohio State specialists. Nitrates accumulated most when drought occurs at or immediately after pollination, says agronomist Peter Thomison.
Corn plants take up the greatest amount of nitrates from the soil during pollination.
Dry weather can impede conversion of nitrates to a form usable by the plant, and nitrates then accumulate in stems, stalks and other conductive tissues. Consequently, farmers should wait three to four days after a rainfall before harvesting, Thomison says. Rainfall will flush the plant with nitrates from the soil, and delaying harvest allows plants time to convert nitrates to non-toxic forms. Don't be too concerned about long dry periods before harvest, because plant roots need soil moisture to absorb nitrates. Also, if pollination went well, the nitrates will go into the ears where they will be converted to proteins and other plant metabolites he says.