Agriculture Sphere

Why is waste useful in hydroponics?

One of the most important elements for life is nitrogen. It makes up 70% of our air, is present in all proteins, and is even helps make up our DNA. The most important role of nitrogen in hydroponics is the nitrogen cycle. The nitrogen cycle is how nitrogen in the environment gets into our bodies as proteins. The nitrogen that can be absorbed by plants and eventually humans is in the form of nitrates.

In a nitrate particle, one atom of nitrogen is bonded to three atoms of oxygen. This is absorbed by plants and used to make protein. When animals eat the plants, they then absorb the nitrogen in the protein as well. When they die, bacteria break down the waste, and convert it to ammonia. After that, other bacteria convert the ammonia into nitrates again. In addition to that part of the cycle, there are also bacteria that can take nitrogen from the air and convert it into nitrate.

These are called nitrogen-fixing bacteria, and usually live on legumes, such as peanuts. Since they have such a good source of nitrates, legumes are usually very rich in proteins. This cycle is very important for hydroponics, since it allows the colonists to use most of the waste from the colony. Since urine is a rich source of urea, a nitrogen-rich compound, the colony can use this to fertilize its food. The reason that urea is so important is because it not only contains nitrogen, but it contains two amine groups. Amine has a chemical formula of NH₂, while ammonia is NH₃. This means that to convert the amine in urea to ammonia, and eventually nitrates, only one hydrogen needs to be added. This makes urea extremely valuable to the hydroponics workers on Koinae.

Test the effect of nitrates on plants! Nitrates can be bought as fertilizer at most home improvement stores, such as the Home Depot. It is very inexpensive. A 5 lb. bag (2.3 kg) can be bought for around $5.00 US. It is called Sodium Nitrate, or sometimes Soda of Nitrate. To test its effects, obtain some plants that grow quickly, such as pea plants. Water one plant with water only. For the other, dissolve some of the sodium nitrate into the water that you use to water it. Periodically measure the heights and observe the color. If you perform this experiment, we'd love to see your results!