Nitrates are commonly referred to as NO3-. In the context of soil-based agriculture, this is the result of bacteria, such as nitrifying bacteria, converting various forms of nitrogen (N) to nitrate (NO3-). Nitrate nitrogen represents the nitrogen that is combined in the nitrate ion, also known as NO3-N. This is different from other types of nitrogen combinations such as ammonia (ammonia nitrogen), nitrite (nitrite nitrogen), etc. Now, nitrogen solubility may differ between compounds. But for nitrates (and specifically nitrate nitrogen), they dissolve in water readily. This is what farms often wish to prioritize when looking for how much available nitrogen is in a nutrient or fertilizer product.
It’s important for farms to understand why nitrate nitrogen needs to be tracked. Nitrate nitrogen can be sourced right from our backyards as a result of water movement.
Nutrient runoff is a significant environmental problem for this exact reason. The rate of groundwater pollution has caused such a stir that the US Public Health Service set drinking water limits for nitrate nitrogen at 10mg/L. For many soil-based farms, knowing what their soil’s nitrate nitrogen levels are is crucial as it could potentially impact underground water tables, which may in turn will affect consumers. However, this also applies to soilless farms as well. Typically, farms that use non-recirculating nutrient systems such as “run-to-waste systems” must find a way to dump or discharge this wastewater. The volume of this wastewater depends on the number of times the farm flushes its system with a fresh supply of source water and nutrients. When using mineral salts as fertilizer most farms practice flushing every two to three weeks in order to remove the residual salt crusts that form in their irrigation lines and reservoir and to remove the residual high sodium content of their water.
The difference between nitrate nitrogen and other fertilizer compounds
In terms of nutrient management, farms have a slew of options when it comes to using nitrogen-based fertilizers. Firstly, differentiating between slow-release nitrogen (Eg: calcium nitrate, ammonium nitrogen) compared to controlled release nitrogen (coating urea granules with a water-insoluble, semipermeable, or impermeable material, delaying the release of Nitrogen from the urea) is important. Additionally, farms should be aware that nitrates are different from other fertilizer compounds in that they synergistically promote the uptake of cations (we’ll explain what these are in an upcoming article), such as K (Potassium), Ca (Calcium) and Mg (Magnesium), while also helping crops make its own amino acids.
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