Denitrification and Volatilization, Why Do They Matter?
All life on the planet relies on Nitrogen.
Nitrogen, a chemical element, is vital for plants because it’s a major component of chlorophyll, the compound by which plants use sunlight energy to produce sugars from water and carbon dioxide (photosynthesis). It’s a major component of amino acids, the building blocks of proteins. Without proteins, plants wither and die.
The challenge for every farmer is to create conditions for plants to uptake the maximum amount of nutrient fertilizer using the minimum amount possible. With the rising costs of nitrogen based fertilizers, lack of knowledge of efficient application methods of fertilizers, and the rapid acidification and depletion of organic matter in farmlands, it becomes important to understand the reasons for nitrogen loss and apply solutions to mitigate its effects.
What is Denitrification?
Denitrification is an important source of N loss from agricultural soils. Denitrification i a process where bacteria convert plant-available soil nitrate (NO3-) into nitrogen (N) gases that are lost from the soil. In normal, aerated soils, bacteria break down organic matter in the presence of oxygen to produce carbon dioxide, water and energy. But in very wet or water logged soils, oxygen is rapidly depleted, so bacteria use nitrate instead of oxygen for respiration. The loss of plant-available N leads to lower yield and a decline of quality of harvested produce.
When does it Occur?
Denitrification occurs in flooded or saturated soils during periods of warm temperatures. Microorganisms take oxygen from the nitrate (NO3–) thus leading to Nitrogen escape into the air as gas.
What is Volatilization?
Volatilization is another form of loss of nitrogen (N) as urea. It occurs when surface-spread urea nitrogen is changed to ammonia gas (NH3) and lost into the atmosphere due to a combination of warm weather and the lack of incorporation of the urea into the soil.
Several field practices can be considered to reduce the loss of nitrate through denitrification. These include:
- Soil Drainage: Poorly drained soils that are excessively wet have poor production potential. Placing drainage pipes and ditches in fields can help reduce waterlog, which reduces the potential for denitrification.
- Soil Texture: The use of rich organic carbon-based material such as cocopeat or carbonized rice hull allows clay-ey waterlogged soils to aerate and drain properly. This allows more mi
- Slow Release N Formula: By slowing the conversion of ammonium to nitrate, there is less exposure of the N fertilizer to denitrification processes at any one time.
- Fertilizer Practices: It is conventional knowledge to incorporate nitrogen based fertilizers into the soil rather than broadcast onto soil surface to increase effectiveness and efficiency of fertilizer.
- Irrigation Practices: Using drip irrigation delivery systems are more efficient in providing the right amount of water to the plant which reduces the potential for nitrogen losses due to denitrification or volatilization.
Efficient Use of a Fertilizer
Slow Release Coated Granular Fertilizers
Fertilizers in granular form that have an additional layer of organic/inorganic coating lengthens the time it takes for the granule to deplete into the soil or into the atmosphere. Slow release fertilizers outperform conventional granular fertilizers and reduce the long term costs of fertilizer applications. Placement decisions should maximize availability of nitrogen to crops and minimize losses. A plant’s roots usually will not grow across the root zone of another plant, so nitrogen must be placed where all plants have direct access to it. To avoid early denitrification or volatilization, always bury the fertilizer granules a few inches into the soil.
Sticker-based Foliar Fertilizers
Foliar fertilizers with unique sticker based formula are fertilizers with a glycerin based sticker formula that allows the fertilizer to remain longer on the plant leaves. This allows the plant to take several days to uptake nutrients through the stomata, tiny openings on the plant leaves used for respiration. Foliar fertilization is a great way to rapidly dose plants with necessary nutrients and can supplement a plant’s needs when plant roots are challenged by rootrot or disease due to waterlogging or fungal/viral infections.
Water Soluble Fertilizer (WSF) for Drip Irrigation Sysems
Drip irrigation systems are indispensible for areas focused on the conservation of water. Drip irrigation emitters deliver nutrient solution directly to the rootzone of a plant thereby preventing wasteful applications. In selecting water soluble fertilizers, it is important to choose high quality fertilizers with 100% solubility to prevent clogs inside the drip lines and filters.
Since Nitrogen is easily lost, it is important to include a source of humates with every application of Nitrogen. Humates act as a chelator or “claw” to hold onto Nitrogen, as well as other nutrients in your soil, enabling a slow release of Nitrogen, making your nitrogen application more effective and more efficient.
Humic acid in potassium humate form is an excellent way to condition soil (or in hydroponic systems). Learn more here.