Nitrate Sampling of Plants and Forages

Nitrate levels can vary widely within a field or hay lot, so collecting a representative sample is important. The sample should represent the forage the animal is actually eating.

Nitrate Testing

Nitrate toxicosis is a concern for livestock and can occur when animals ingest forage or feed (or water) with a high nitrate content. The NDSU-VDL tests for nitrate in feed samples by a quantitative for nitrate levels by ion selective electrode. It is important that a proper and representative sample is sent into the diagnostic Lab for testing.

What to send

  • Submit approximately 1 gallon of fresh forage or hay in a clean bag.
  • Do not include roots.

Hay or baled forage

  • Use a hay probe to collect cores from at least 10 bales from the same cutting/lot.
  • Combine the cores to make one representative sample.

Corn stalks, pasture, or other standing forage

  • Cut plants at the height the animal would normally consume.
  • Collect samples from 4–5 locations across the field and combine them into one sample.
  • If some areas appear more drought-stressed or contain more nitrate-accumulating weeds (such as pigweed, dock, Canada thistle, or lamb’s quarters), consider submitting a separate sample from those areas.

Storage and Shipping

Proper handling is important because nitrate levels can change after the sample is collected.

  • Fresh or moist forage: Place in a plastic bag and keep cold or freeze until shipped.
  • Green/immature plants: Freeze overnight and ship on ice packs when possible.
  • Dry hay: May be kept at room temperature overnight before shipping.
  • Ship samples as soon as possible, preferably overnight.
  • Avoid shipping late in the week to prevent delays in testing.
  • Do not allow fresh samples to remain warm for extended periods, as nitrate levels can decrease during storage.
  • Important: If sampling crops for livestock feed or grazing, also consider any recent herbicide or pesticide applications and applicable livestock withdrawal intervals.

Revised 08-2026

Printable version available here.