Is there a difference between Nitrogen and Nitrates? Why would I use one over the other when discussing water quality, fertilizers, or agriculture?
In: 0
Nitrogen gas is two nitrogen atoms bound tightly together. It takes so much energy to break that bond that there are very few processes in biology that can do it. Living things need bioavailable nitrogen compounds for things as basic as DNA and protein synthesis. This is *mostly* in the form of nitrate, but not exclusively.
For example, if you pee in a bucket and use it to fertilize your garden, the nitrogen is in the form of urea, which plants cannot absorb. Bacteria convert it to ammonia, which is a gas that is easily absorbed by water. Some plants can absorb ammonia directly, but most wait for bacteria to convert it to nitrates and nitrites. But those aren’t the only forms of nitrogen in the soil- earthworms contain a significant amount of bio-available nitrogen. You might purchase bloodmeal to fertilize your garden- dried blood from slaughterhouses. This is protein, a complex mixture of proteins, but it is equivalent to about 12% nitrogen by weight.
This is why it is proper to talk about how much nitrogen a biological system contains. It is technically referring to “fixed nitrogen”, but it is most common just to omit the word “fixed”. All of those biological systems exist at the bottom of an atmosphere with billions of tons of nitrogen gas, but it is so inert that it is irrelevant to most discussions of biological processes. If you just refer to nitrate, you’re talking about one specific chemical form. Talking about “nitrate” doesn’t include ammonia, which becomes nitrate in a few weeks, or urea, which becomes ammonia in a few days, or living flesh, which turns into those things when it dies.
Latest Answers