The Nirogen Cycle & My Aha! Moment

I had one of those aha moments while I was servicing aquariums when I first arrived in melbourne from Cairns in January 2011in regard to the nitrigen cycle. I finally got it and just how important it is for us that grow food in the backyard without synthetic fertilizers. I like to grow food by recycleing organic waste and manures.
The same principle applys to aquariums and how that micro ecosystem recycles the fish waste, as it does with gardens and how the nitrogen in organic matter is recycled back to a usable form.


Carbon, water, sulphur, phosphours and nitrogen are in constant motion, absorbed and used by organisms then broken down reincarnated and used again.
So how does the nitrogen cycle work? Nitrogen is an essential to DNA, RNA and proteins. When we eat a steak or vegetable we're eating also millions of strands of DNA, RNA and proteins. The air we breath contains 78% nitrogen but it's so tightly bound together in the N2 molecule it's not available to be used by plants at all. One way to make nitrogen available to plants was discovered in the early 20th century by Fritz Haber using high temperatures and a metal catalyst and has led to the green revolution agriculture is able to support 4 billion people on the planet that it others could.

The other way and of interest to us is via bacteria and their enzymes and fungi. I've talked about nitrogen fixation in previous blogs please do a search.
5.8 billion tons of nitrogen is moved around each year 87% of this through living organisms, also
440 million tons of carbon is moved each year 45% of this be living organisms.
740 billion tons of phosphorus 99% of which by living organisms.

This brings us to the nitrogen cycle. The first step in making nitrogen in organic matter available to plants is called mineralization or simply decay. decay is done by bacteria and fungi during this process the nitrogen is converted to ammonium NH4+ which sticks to clay and humus particles ready for plants to take up.

Some of the ammonium is converted to nitrate NO3- in the next process called nitrification as bacteria gain energy for life in this conversion process.The fact that the nitrogen is now negatively charged and does not stick to clay and humus in the soil is significant as it can be easily leached out with rain into waterways.

The next process is denitrification where the NO3- and the NO2- forms are converted back to N2 and back into the atmosphere again by bacteria.The amount given back by denitrification is roughly equal to the amount fix by bacteria from the air.

So biologically active soil that's alive and has about 5% organic matter will supports the life of plants significantly better than biologically inactive soil.