Ammonium Nitrogen Fertilization Impacts
Soil Organic Matter and Crop Yields
Many crops, especially crops like corn, need a lot of nitrogen to produce high yields. Most nitrogen is applied early in the season to agronomic crops using ammonium-based fertilizers. Ammonium forms are cheaper and less likely to leach than nitrate nitrogen. Common forms of ammonium nitrogen are urea, anhydrous ammonium, urea ammonium nitrate (UAN), diammonium phosphate (DAP), monoammonium phosphate (MAP), and ammonium sulfate. However, there are some negative consequences to using high levels of ammonium-based nitrogen fertilizers, especially when applied early in the growing season.
In the soil, when microbes have readily available nitrogen, they will use this nitrogen and available carbon for energy to grow. Crop residues are a primary source of carbon for microbes. The breaking down of crop residues is generally beneficial to the soil. However, with elevated nitrogen levels in the soil and depleted crop residues, these microbes will also use available active carbon in the soil organic matter as their carbon source. This reduces active carbon in the soil. The bottom line is that continued use of high rates of nitrogen fertilizer overtime can lead to reduced organic matter content in soils.
Another consideration with high levels of ammonium fertilization is that ammonium accumulation inside the plant is actually toxic. It is a free radical that can disrupt many biochemical pathways. Because of this, crops will seldom have more than 5 ppm of free ammonium in their tissues. To detoxify excess ammonium inside its tissues, a plant will quickly convert ammonium into proteins. This process consumes carbohydrates that are needed for growth. Excessive ammonium nitrogen fertilization can actually have a negative impact on crop growth and development. A real world example of this is when dry beans are planted following 2-3 years of corn, and high levels of ammonium fertilizer are applied as their primary source of nitrogen. The nitrogen fertilizer stimulates rapid vegetative growth, but the resulting depletion of carbohydrates in the plant can cause the abortion of the early flower clusters, thus delaying pod set and bean maturity, and also reduce overall yield of the crop. See our Dry Bean Study.
The potential loss of yield and loss of organic matter in agricultural soils is real. Humi[K], available through AgriGuardian™, is an economical way to reduce these losses. Humi[K] contains both humic and fulvic acids, and contains “active carbon”. Humic acids occur naturally in soils, and are a natural part of soil organic matter. “Active carbon” is the most beneficial part of humic acids. It is responsible for helping to make plant nutrients more available for crop uptake, helping to balance nutrient availability (including reducing salt levels in the soil), and stimulation of beneficial soil microbial activity. Humi[K] also has readily available potassium (K) which helps to offset the negative effects of excessive nitrogen in growing crops. When Humi[K] is used, fertilizer efficiency increases, and it reduces the detrimental effects of excessive fertilization and pesticide usage. Just because soil has good organic matter content does not mean that it has sufficient humic acid content for optimum crop growth and yield. Most agricultural soils will benefit from the addition of Humi[K].
Contact your local AgriGuardian™ distributor for more information on Humi[K] and our other products.
