Sunday, 4 September 2022

Thoughts on Synthetic Nitrogen

 

Back in the day, long, long ago (!), I learned from my parents, who worked at Lincoln University, about about using clover and lotus species as a means of fixing nitrogen in pasture.  Legumes like clover  or lotus form relationships with soil bacteria which take nitrogen from the air and turn it into nitrates.  The idea was to grow clover in amongst ryegrass as a means to keep the grass growing and to provide feed. 

Clover plants

Along came the 1970s, when the "Think Big" projects got underway. One of these was the Kapuni ammonia urea plant.  For this project to be profitable, farmers were encouraged to use synthetic nitrogen fertilisers (SNFs)  as part of their farming operations. Of course, the result of that along with the development of irrigation, was the intensification of farming – something that has impacted rivers, soils and climate and now we have a problem! 

Farmers have learned to manage the application of urea fertiliser so that it doesn't simply run off into the waterways.  However, the urine produced by the cows is a major issue since we have such high numbers of cows.

It is interesting that, we didn't need synthetic nitrogen fertiliser prior to the 1970s and farms profited by using nitrogen fixing plants to do that work – largely for free.

Second, there have been significant changes in our understanding of soil ecology and our understanding of the importance of the living elements of the soil and the levels of carbon in the soil. Farmers testing out regenerative techniques are building on the sort of things my mum used to teach back in the day and have extended on it significantly.  Farming in this regenerative way is much more about focusing on the health of soil ecosystems as opposed to soil as chemistry.  There are also farmers experimenting with how to do this best in modern cropping systems.

Lotus flowers

I know some farmers who stopped using synthetic nitrogen many years ago now because of the expense.  They haven't gone back to it and instead use a lower input, lower output model of farming that is better for them, and better for their soils and stock.  Some dairy farmers have found that this lower input/ lower output model also works for them.

At the same time, for farmers with a LOT of debt who have the bank breathing down their necks, making a move to a new way of doing things will be incredibly scary.  Farmers will need good support to shift their farming systems away from using SNFs so that that they can manage their enormous mortgage repayments and their stress levels.

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