Caution on Grazing Drought-stressed Grain Crops
Montana livestock producers should be cautious in grazing drought-stressed cereal grain crops this summer due to potential high nitrate accumulation. Due to the persistent drought for the past three years, the acreage of annual forages such as hay barley, oat, millets, sudangrass and others has increased dramatically. Also many acres of drought-stricken wheat or barley will not produce a viable grain crop, and these are being considered as pasture to salvage some value. Unfortunately, under droughty conditions all of these crops (and many weeds such as kochia) can accumulate levels of nitrate that are toxic to livestock. Nitrate (NO3) from the soil is converted to amino acids and protein when crops are grown under normal conditions, but with drought or temperature stress, the nitrate can accumulate at toxic levels. High nitrate levels can reduce animal performance, but in extreme cases results in abortions and death. The highest risk is for pregnant beef cows in late summer, and bred cows or ewes in the fall. A complete description of nitrate toxicity and some guidelines are available in MontGuide 200205:
What should you do?
The MSU Extension Service uses the Nitrate QuikTest to detect potential high nitrate levels. Before haying or grazing any cropland that could potentially have a nitrate problem, you should contact your county Extension agricultural agent to arrange to have your crop tested. In many cases, a laboratory analysis is required to confirm the nitrate concentration. This summer, many fields have been found to contain hazardous nitrate levels, and these should be avoided for pasture or hay production. Depending on future cropping needs, these fields could be tilled now or left standing to catch snow next winter Further, when purchasing hay of these crops for winter feeding it is advised to have a forage analysis for nitrate, protein and energy to indicate any potential winter feeding problems.