News & Insights

The Science Behind It: Nitrogen Cycle

“The Science Behind It” is an educational video series by Dr. Tuesday Simmons, science writer at Trace Genomics. It was created to illuminate the scientific foundations of soil microbiology that form the basis of Trace technology. In this video we delve into the complexities of nitrogen management in agriculture as we uncover the intricate processes and challenges involved in optimizing nitrogen use for crop growth and environmental sustainability.

Video Script:

In the soil, there are three essential macronutrients that plants need to grow – N (nitrogen), P (phosphorus), and K (potassium). These are often added to fields as organic matter, manure, compost, or chemical fertilizers to give crops the best chance of success. Farmers often consult agronomists to optimize nutrient management so they’re applying what they need.

I’ve talked about phosphorus in a previous video, and if you think about the phosphorus cycle as a game of checkers, then the nitrogen cycle is chess. What makes nitrogen more complicated is that it’s present in more forms than phosphorus, and soil microbes are involved in almost every step. Even boiling down the nitrogen cycle to the most agronomically important parts is still pretty intimidating.

In practical terms, this means that there are more avenues of nitrogen loss for growers to be concerned about. Like phosphorus loss, most avenues of nitrogen loss have negative impacts on the environment, and on a grower’s wallet. In addition to leaching and runoff, nitrogen can also be lost through volatilization or denitrification – as gasses that end up in the atmosphere instead of in plants.

Also similar to phosphorus, not all of these forms can be used by plants. The forms of nitrogen that can be taken up by plants are nitrate and ammonium. Microorganisms in the soil help facilitate these transformations using enzymes – proteins that speed up chemical reactions. The “instructions” for these enzymes are found in the microbes’ DNA, and by sequencing all the DNA with metagenomics, we can detect all these enzymes – even in microbes that have never been cultured in a lab or identified at all.

At Trace, we report five different indicators that impact the nitrogen cycle. Urea volatilization potential, nitrification potential, and denitrification potential can all contribute to nitrogen loss. Nitrate ammonification potential is a microbial process that converts nitrate back into ammonium, which is more stable in the soil. We also report species of nitrogen fixing bacteria – some that form a symbiotic relationship with plants, and some that are free-living in the soil.

Using Trace nitrogen indicators as part of a soil fertility management plan can help agronomists optimize product placement for retention of nitrogen. This can protect valuable investments in soil nutrients and help conserve soil health for future generations.

About the author: Dr. Tuesday Simmons is the Science Writer at Trace Genomics. She earned her Ph.D. in Microbiology from the University of California, Berkeley, studying the root microbiome of cereal crops.