PW Burton
We’re all aware that nitrogen is one of the essential elements to get plants to grow.
What some farmers don’t seem to realise is that there is already tonnes of it in our soils, not to mention it being a major part of the air around us. The only hitch is that this soil or air nitrogen needs a bit of help from nature to make it suitable for plants to use.
The help could come from mycorrhizal fungi and bacteria, which do the trick of turning the soil and air nitrogen into plant usable forms.
In the late 1970’s, before farming started on the ‘urea track’, NZ scientists had estimated that there could be a reservoir of up to 14,000kgN/ha, with between 3,400 and 6,800kg of organic N/ha in the top 150mm of soil.
But if the ‘soil life’ isn’t there, or not in sufficient quantities, then all that ‘free N’ can’t be got at by plants. The answer should have been to boost the soil life and let nature get on with it. But what happened was that the urea plant was built, and now farmers can be heard to say ‘You can’t grow grass without urea’, and they believe it!
And it’s not just this misperception going around. Regular urea applications tend to decimate the very mycorrhizae and bacteria that could and should be doing the job. Not only this, but the clover plants, which used to be part of the process in fixing nitrogen for free, are weakened by constant urea applications. We pride ourselves on growing ryegrass/clover pastures, but how much clover can still be seen in many of them? It has got tired of not being able to do what it does best, and faded away.
What our pastures really need is sweetening up with regular calcium (lime), along with major and minor elements to be applied where soil tests have shown shortages, and mixtures enhanced with carefully chosen mycorrhizae and bacteria to help the soil life that’s already there.
Functional Fertiliser Ltd has been measuring dry matter production on several farms using their products for over a decade now. And the production levels are getting bigger every year with no added N, as tests have proved that there is already about 9,400kgN/ha in the top 300mm of the soil (the depth to which plant roots can penetrate freely).
So when the payout looks like never recovering, why spend the precious budgets on something you don’t need, when you could be spending it on something really useful that makes low-cost, highly nutritious grass grow?
And the prize to top it all off is that you could soon be leaching up to 70% less N into our streams and groundwater. Solving two problems at one go!
For more info, call Peter on 0800 843 809
