Very few forages, particularly corn, contain levels that will produce toxicity. Feeding should be delayed until the fermentation process is complete. This usually takes about 4 weeks. Purdue University studies have also shown that addition of 20 pounds of limestone per ton of silage going into the silo further reduced nitrate levels. Addition of more than 20 pounds per ton adversely affected fermentation and quality of the silage.
Limestone tends to raise the pH which, in turn, can reduce silage quality.
Nitrate levels in silage also can be reduced by chopping the top two-thirds of the plant since nitrate accumulation is highest in the bottom third of the stalk or stem. Leaving that much of the plant in the field is often a difficult decision but it may be less costly than the possible loss of animals. Stalks left in the field can be a source of nitrogen for next year's crop. Proper ensiling procedures improve the fermentation process and help to reduce nitrate levels. Application of anhydrous ammonia to drought-stricken corn is not recommended.