I saw this picture the other day and it immediately made me think of the huge financial value that smart farm management provides, especially with regards to soil health and nutrient management. The greatest limiting nutrient for plant growth is nitrogen. This makes nitrogen an important fertiliser, but excessive nitrogen application is associated with numerous negative environmental impacts. Examples of these impacts are greenhouse gas emissions and eutrophication. Nitrogen is therefore the nutrient which receives the most attention when discussing sustainability.
I am not one of those people who just think farmers should stop all forms of nitrogen fertilisation and just “go back to the good old days”. Food security relies too greatly on productive commercial agriculture to just stop pushing for greater production. I am a strong advocate for the responsible use of natural resources for productive and efficient commercial agriculture. When it comes to nitrogen, this means exploring alternative sources to purely relying on chemical fertilisers. Not only are chemical fertilisers bad for the environment, they are also expensive and relatively inefficient (a lot of the nitrogen is lost through leaching and volatilisation).
The question therefore becomes, how can commercial farmers do this better? Well that is where the alternative nitrogen sources come in:
- Nitrogen mineralisation is the process which breaks down organic nitrogen in the soil into inorganic (ammonium and nitrates) nitrogen. This inorganic nitrogen is readily available for plants to use. Mineralisation is the key process in the natural cycling of nitrogen between the soil and plants.
- The roots of legumes have nodules containing nitrogen-fixing rhizobium bacteria, which are able to transform atmospheric nitrogen gas into ammonia, which is further converted into plant-available ammonium in the soil.
- Compost is an organic form of nutrients, also containing beneficial micro-organisms which, when added to the soil, contribute to mineralisation and the natural cycling of nitrogen.
- Other organic forms of fertiliser, such as chicken litter, are less harmful sources of nutrients than chemical fertilisers.
Not only are these alternative sources of nitrogen much cheaper than chemical nitrogen, they actually contribute to healthy soil and a healthy agro-ecosystem. Chemical nitrogen does the opposite. Money in the bank is therefore through immediate savings in fertiliser costs, but also in the long-term sustainable profitability which results from a healthy, productive and efficient farm.