The Nitrogen Cycle Episode 3 in the Garden Soil Series

On todays episode we are going to talk about one of the most important elements for your Garden. Nitrogen.

Nitrogen is an base element with an atomic number of 7. Nitrogen is the largest component of the air we breathe at 78% of earths atmosphere and is the 7th most abundant element in the universe
So why is Nitrogen so important to our gardens? Nitrogen plays a key role in the development of amino acids and DNA. Amino acids are they key building blocks for all cells and the DNA form the database of the body.
Now that we know how important nitrogen is lets talk about the nitrogen cycle. The cycle defines the process of atmospheric nitrogen moving into the food web and back again. Nitrogen in its atmospheric state is not plant available. Nitrogen has to be in an organic form like ammonia NH3- and nitrates N03-
There are two main ways organically available nitrogen. Plants and animals produce ammonia as waste. You can recycle your plants nitrogen through composting and the same thing with things like rabbit manure. Every time you recycle nitrogen some is lost as atmospheric nitrogen though process called Denitrification.
So how do we get Nitrogen from the atmosphere to make it available to the plants. The second way is nitrogen fixing process. There are two main ones. The first is Nitrogen fixing bacteria. They take N2 from the atmosphere and make ammonia or NH3. Then a second and third process with bacteria convert the ammonia to nitrate which is available to the plants.
The other way to fix nitrogen is through the Haber-Bosche process where you take atmospheric nitrogen, Hydrogen and pressure to create Nitrates. Which is typically how commercial fertilizers get their nitrogen.
What does this mean for your garden. There are two ways you can organically add nitrogen to you garden. Compost and nitrogen fixing plants with beneficial microbes.
Compost is typically made with both Green and Brown materials. Green materials such as grasses and manures are nitrogen rich and Brown materials are carbon rich such as wood chips. By both hot composting and vermicomposting I typically add them to my garden. Application of completed compost can be mixed directly or as mulch on top of the soil. uncompleted compost material can be added as mulch to the top. Be cautious as you do not want to create a hot compost in and around your garden plants.
You can also add nitrogen to the garden by fixing the nitrogen in place. This is typically done by planting nitrogen fixing crops like peas and alfalfa. both of these plants send out hormones into the soil attracting nitrogen fixing bacteria. When the nitrogen fixing bacteria come in contact with the plants roots they ave enveloped in a node. The bacteria then produce bio-available nitrogen for the plants and the plant gives the bacteria carbohydrates.
The bio-available nitrogen is released into the soil when the plant dies through both the node and the plant material being composted. This is commonly referred to as green manure.
As your plants grow or when you take a ripe tomato or fantastic raspberry from the garden you take a little of the nitrogen with it. It is important to continue to build the nitrogen in your soil by adding compost and providing a great habitat for the happy and beneficial microbes.
Next time we are going to talk about the nutrient cycle.

About Stephen

The Alberta Urban Garden Channel hopes to promote organic gardening that is simple, sustainable and does not have to cost a lot. We do this by investigating the Science behind gardening, methods, practices and products to make sure that you will have the best chance of successfully growing your own food at home.