• Lancaster / Wi

Nitrates

What is a nitrate (NO3)?

Chemically, NO3 are a combination of two elements, nitrogen and oxygen, in the proportion of one nitrogen atom combined with three oxygen atoms.

 

Where does NO3 come from?

  1. NO3 in Water & Feed.
    1. NO3 in the water and feed supply can come from several sources. A primary source is fertilizer containing a nitrogen source. For example, potassium nitrate (KNO3), ammonium nitrate (NH4NO3), urea (CO[NH2]2), and anhydrous ammonia (NH3), common in a variety of frequently used fertilizers, are all sources of NO3, since the NH4+ and NH2 groups can both be oxidized (i.e., broken down) by air and bacteria in the soil to become NO3. Furthermore, manure and urine are also excellent sources of NO3. The form of nitrogen in manure and urine is mostly NH2, but also includes NH4+ and proteins (proteins are carbohydrates with NH2 groups attached).
    1. Natural Sources.
    2. In some parts of the world, there are natural deposits of NO3.
    1. NO3 in Plants.

    2. PHOTOSYNTHESIS
      Photosynthesis

      Plants (e.g., grass, hay, corn silage, etc.) and several types of bacteria can make their own NO3. Some types of bacteria in the soil are solely associated with plants, such as legumes (symbiotic bacteria), while other types live everywhere (asymbiotic bacteria) taking the nitrogen from the air (air is 78% nitrogen!) and fixing it into NO3, which then can be utilized by plants. Most plants take up nitrogen from the soil in the form of NO3. NO3 are absorbed by the roots and transported up the stalk with water. Carbon dioxide (CO2) is absorbed from the air and into the plant through the leaves (via stomata).

      PHOTOSYNTHETIC REACTIONS
      Photosynthetic Reactions

      During photosynthesis, a water molecule (H2O) is split and oxygen (O2) is released into the air for us to breathe. The leftover hydrogen atoms are then combined with CO2 to become sugar, starches, fats, cellulose (e.g., fiber, wood, etc.), and will also combine with NO3 to become amino acids, the building blocks of proteins. Here is where a problem with NO3 in the plant can occur.

      First, there must be plenty of water. If the plant is stressed from dehydration, after the photosynthetic reaction there will not be enough hydrogen to convert NO3 into an amino acid. Thus, the unused NO3 just sits around waiting for more hydrogen. Second, if there is a lack of sunshine because of cloudy/rainy days, night-time, or frost (i.e., frozen water) NO3 can accrue because without the sun, there is no photosynthesis.

      Helpful Hint #1: Never cut hay in the early morning.

      Helpful Hint #2: Do not overgraze, NO3 are higher in the lower parts of the plant.

     

    What are the effects on cows, bison, sheep, people, & pigs?

    There are two ways NO3 become a health risk. One way is that the ingested NO3 will be converted to ammonium (NH4+), which is absorbed into the bloodstream. Once the NH4+ is absorbed into the bloodstream, it combines with hemoglobin, inhibiting hemoglobin from binding oxygen and preventing the transport of oxygen from the lungs to the cell. The hemoglobin attached to NH4+ is called methemoglobin. Young animals are affected the most by this. When enough hemoglobin is converted to methemoglobin, the animal begins to suffer oxygen starvation. In humans, this is called "Blue Baby Syndrome." In cows, it is often described as "hard breathing."

    Helpful Hint #3: Some summertime hard breathing is not a result of the heat; it is from an imbalanced feed ration!

    Second, bloating can also occur when NO3 is converted to NH4+. NH4+ is an alkaline substance, which will increase the pH in the rumen. Increasing rumen pH will depress growth and multiplication of rumen microflora (bacteria). Excess NH4+ in the rumen is also associated with a considerable number of additional health problems, including foot rot, mastitis, retained placenta, pink-eye, breeding issues, respiratory infections, etc. Excess NH4+ from high protein rations will compound the problem.

     

    NO3 levels in feed & water with respect to animal response.

    NO3 Level

    Animal Response

    Feed

    0 - 0.20% Considered safe; minor health/production problems
    0.2 - 1.5% Potentially toxic
    > 1.5% Death

    Water

    0 - 8 ppm Considered safe
    8 - 100 ppm Likely health risk
    ≥ 100 ppm Potentially toxic