The heat is on throughout the country, ryegrass has headed out and pastures are becoming full of clover. 

Some paddocks will even be turning white, red, or yellow with their flowers.

As spring pastures are eaten out, more light gets down to the clovers helping them grow. Plus their optimum growing temperature is about 5C higher than ryegrass which is why it becomes more dominant now and will be stopping your milksolids in the vat from falling.

Just like with ryegrass, there are lots of different varieties to choose from when regressing or if you’re thinking about oversowing a paddock.

And there is just about a variety for every soil type and climate, so diverse is this little legume.

White clover is the usual choice for New Zealand pasture and is classified by the size of the leaf. Generally, the smaller the leaf size, the more persistent and low-growing the plant will be.

White clovers have stolons on their stems which creep along the ground and each growing point on the stolon can become a new plant.

Large-leafed white clovers, such as Kakariki and Kotuku, grow taller, are more upright, and have thick stolons and robust roots and are higher yielding.

However medium-leaf clovers, such as Huia and Tribute, have more stolon growing points so are more persistent.

Small-leaved clovers, such as wild white clover, are the most persistent of all with lots of stolon growing points but they are so low growing only sheep can usually get a good nibble off them. 

Red clovers, which have tap roots instead of stolons, have a red flower instead of a white one and are usually short lived – lasting only two to four years.  

Subterranean clover, also known as sub clovers, are getting their share of the limelight lately for their ability to survive the dry and their early spring growth. They are an annual clover so must be allowed to set seed each year to survive so don’t eat them off at the wrong time.

Lotus major is tolerant of wet and acid soils and shade so expect to see its bright yellow flowers in peat country and on the West Coast. It has underground rhizomes which can store carbohydrates in autumn for overwintering. 

Lotus corniculatus (birdsfoot trefoil) grows well in low fertility soils in regions with warm, dry summers.

And then there are some other varieties that are getting farmers excited. 

Persian clover, from the dry areas of Turkey, Iran and Iraq, is self-regenerating and can be grown on its own as a forage crop or used in pasture seed mixes.

Crimson clover, known for its colourful tall flower heads, is a fast-growing clover for cooler temperatures.

Whatever clover you choose, you can easily spot the seed in grass mixtures. Clover seed is smooth, small and round. It’s usually sown at a rate of 3-4kg/ha.

But why should we worry about these little plants, and make sure they’re part of our pasture sward?

Because they are a legume, and legumes (peas, beans and, sorry, gorse) fix nitrogen in the soil from the air which grass doesn’t do.

So, if you are trying to reduce your nitrogen fertiliser usage, then these are the plants you need to think about.

Clover actually struggles in pasture grown with high rates of nitrogen fertiliser.

But it isn’t the clover that does the nitrogen fixing. Legumes have a friendly relationship with a bacteria called rhizobia which hangs out in the nodules of the clover roots. It’s the bacteria in these nodules that take nitrogen from the atmosphere and put it into a form that the legume can use to make protein and grow. 

But clover is not great at sharing the nitrogen its buddy rhizobia has grabbed. 

The only way grass gets it is when a bit of the clover plant dies and breaks down in the soil and then the nitrogen is released – all part of the nitrogen cycle.

Some overseas websites recommend using herbicides to kill clover plants to speed up this transfer of nitrogen before resowing with more clover seed but maybe letting nature do its thing is a better idea.

And remember, when spraying paddocks for broad weeds, thistles and gorse, clover will take a hammering as well and as some of these sprays stay in the ground, especially in low rainfall areas, which might mean no clover plants for a year or more.

But there is another ingredient in this legume and bacteria nitrogen fixing mix – molybdenum.

Molybdenum is an element (Mo on the Periodic Table you may or may not remember from high school) and a mineral. 

The bacteria in the clover roots doesn’t do so well without it, so soils lacking in molybdenum will have lower rates of clover as clover needs its bacteria friend to grow.

Luckily molybdenum can easily be added to fertiliser applications but check your soils are low in it first. It doesn’t need to be applied every year and soils high in molybdenum cause all sorts of problems with stock health, especially copper deficiency, so be careful.

Because the bacteria is fixing nitrogen, clovers are high in protein. About a quarter to a third of clover is protein, compared with grass which is about 10% to a quarter depending on the time of year.

So while most pasture only contains at best 30% clover, it’s the clover that is the nutrient powerhouse for your cows.

But just be aware of bloat. Too much clover, just like any good thing, is not good for cows.

As well as protein, clover also contains calcium, chromium, magnesium, niacin, phosphorus, potassium, thiamine, and vitamin C so, for a cow, it’s a bit like popping a multivitamin.

Unfortunately, a few other things like clover for its high nutritional value such as slugs, the clover flea, a few soil-dwelling nematodes and the clover root weevil which was discovered in New Zealand in 1996 and has spread throughout the country probably hitchhiking on bales of hay.

If your clover leaves look like something took a hole punch to them then you have a problem with clover root weevil.

But the great thing about clover is it flowers every year and those flowers turn into seeds and those seeds can stay in the soil for years before they germinate so even if you do nothing, as long as your soil has enough molybdenum, you will always have clover.

And maybe even a few four-leafed ones as well.