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Rights: University of Waikato
Published 30 July 2013

Dr Ross Monaghan from AgResearch at Invermay in Otago describes the importance of clover in the farming industry due to its ability to fix nitrogen.

Jargon alert: 

  • Nitrogen fixation is the process of converting atmospheric nitrogen gas to forms that can be used by plants and animals for the functions of life.
  • Rhizobia are bacteria that live in nodules on clover roots. They convert N2 to nitrogen forms that can be used by plants and animals.



Early on, it was recognised that we needed phosphorous and sulfur fertiliser to maintain adequate levels of clover in our pastures. The clover plant has really been the backbone of our pastoral industry, up until recent times at least, because clovers have this clever ability to be able to fix nitrogen from the atmosphere in a process known as nitrogen fixation.

And that’s an interesting scientific process where the clover plant plays host to rhyzobia bacteria, and it’s those bacteria that fix nitrogen that allows the clover plant to grow. And the clover plant then is eaten, or the roots or tissues break down and release that fixed nitrogen to the neighbouring grasses. And it’s that nitrogen input that actually is determining how much grass we grow and thus how productive our pastures have been.

What we’ve seen in the last 15–20 years, with the cost of energy going down relative to other farm input prices, it’s become more economic for farmers to use artificial nitrogen fertilisers. This also allows them to be a little bit more strategic as to when that nitrogen is supplied to the pastures, so they can use it in the spring to get a bit of extra grass when they really need it, and it’s also allowed them to apply more nitrogen in total and thus get more productivity.

Dr Ross Monaghan, AgResearch, Invermay
Damon Taylor
McDonald’s Lime