GETTING RESULTS FROM CLOVER
Many farmers would tell you that their pasture is some form of perennial ryegrass and clover.
But when taking a close look at many pastures today you might be hard put to find the clover among the ryegrass. The clover seed went in with the grass seed, so where has it gone?
Part of the problem may well be the pH levels. Clover thrives in sweet soils and therefore responds well to regular applications of lime. And when it proliferates in pasture it not only provides a preferred food source for animals, but it also does what clover does best, it takes nitrogen from the air and tucks it away in nodules on its roots. Thus it benefits not only itself, but also the soil and other pasture plants around it. But if urea is frequently applied, then the clover gets discouraged and disappears. As Dr Jim Crush of AgResearch commented, clover is quite happy to switch off its biological nitrogen fixation and use fertiliser nitrogen for growth, but clover cannot tolerate shading from nitrogen fertiliser boosted grass growth. So often the farmer puts on more urea to compensate, spending money on a product which nature would have provided for him, if the pH of the soil and sward management had been right. Dave Muggeridge of Tatuanui, who now applies lime to his whole farm at 400kg/ ha every year, knows the pH of his soil is now at least 6.3, and the clover is thriving everywhere. He’s still a ‘ conventional’ farmer, but any urea used ( no more than 33kg/ ha/ yr) is only when the wrong weather slows down his pasture growth in mid- season, and he needs some grass in a hurry. The sward in his pastures grows tall and very thick. There are none of the bare patches between plants which are so often seen elsewhere and almost no weeds, because there isn’t room for them to get established. And it’s not just the clover that is being looked after. Dave long ago realised that ryegrasses grow upward, putting out leaves at intervals along a stem. But he also found that there are never more than three growing leaves on any stem, while those below them are dying off. At this stage the pasture has reached its maximum standing crop and, although the ryegrass keeps on growing, there will be no further increase in yield. Thus to get the best value from ryegrass, it needs to be eaten down, preferably while there are only three leaves, or before the lower leaves die off. This means that his cows get the best nourishment from it, and the pasture does not waste energy replacing old leaves with new leaves. This energy is better spent growing the first leaves in the next crop of grass. This grazing strategy also means the clover does not suffer damaging shading from tall grasses. Jim Crush confirmed that the key to maintaining clover in pastures, especially nitrogen- boosted pastures, is getting them grazed before the clovers are shaded out. By keeping his pH up, Dave can keep his urea bill down.