The magic of clover and the legumes.
Clover is in the legume family along with plants like lucerne, Lotus species, lupins and gorse. They all have little nodules on their roots where bacteria called Rhizobia species live. They can convert nitrogen gas into nitrate, which the pasture plants then use as a fertiliser. Clover is also very high in all the nutrients that stock need.
Free nitrogen from clover
This is briefly how it works. There is a large quantity of nitrogen gas in the air (about 80%). In a good healthy soil there should be masses of air spaces - which contain this nitrogen gas. If a soil has no air then it is in fact dead.
The Rhizobia bacteria, living in the little pinkish-white nodules on the roots of legumes, absorb this nitrogen gas and convert it into the compound “nitrate”. When they die nitrate is released into the soil as free fertiliser for other plants to use.
How much for free?
You see some very wide estimates of how much nitrogen a healthy clover plants will provide for a pasture. When the clover weevil was at its worst, it was predicted that if the clover in a good pasture was completely wiped out, dairy farmers would have to proved up to 230kg of Nitrogen/ha to replace it. Thinking of the fertiliser Urea (which is 46% N), this is 500kg of Urea. That’s a mighty amount of fertiliser for free!
It would be reasonable to think of say 100-200kg N/ha from clover, but you do see figures in excess of these amounts. The message is clear, - we cannot afford to farm without healthy clover, so look after it.
How do you care for clover?
- Make sure your clover is correctly fertilised - as you need a healthy plant to have healthy nodules. The nodules should be pink in colour.
- Make sure the clover plants are not shaded out by letting the grasses get too long.
- Try to avoid the clover weevil (bites circles out of the leaves), and the clover flea (that scrapes the soft tissue off the underside of the leaves). If things get really bad and the clover is disappearing, you may have to face insecticide treatment. Seek expert advice.
- Insect pests come and go, so don’t panic unless you have had more than one season of infestation.