There are nine things you should remember about testing drought-stressed forage for nitrates, says Jim Krantz, SDSU Extension cow/calf field specialist:
1) In areas where livestock are allowed limited access to forage, test the upper portions of the plant, as they will not be left there long enough to consume the lower portions of the plant.
2) In rotational grazing systems, or those where livestock will be confined for the entire season, test the lower third of forage where higher concentrations would be expected.
3) Samples need to be representative of the entire grazing resource. They should be a composite of about 10 to 15 areas with similar fertility and moisture
4) Don't mix plants from good and portions of a field. Test each area individually
5) Place dry plant samples in paper bag so that there is no mold build-up.
6) Package moist plants, such as silage or wet plants, in plastic bags and put the bag in a cooler with ice packs.
7) Deliver samples to a lab the same day or ship them overnight with ice packs.
8) Take samples first to any SDSU Regional Extension Center. Staff there can do a quick test to determine if there are nitrates in the sample. If nitrates are present, further testing at a laboratory is required to determine the levels.
9) See www.foragetesting.com for a list of labs that do nitrate tests.