Sound grazing management is a vital component of running a farm and as well as ensuring pasture growth is maximised, it can also have a significant effect on pasture quality, animal health and ultimately the profitability of your farm.

Explained: the solar panels that power your soil and pastures

The reason grazing management is so important is because it has a huge effect on the overall health of your soil and therefore the on-going sustainability of pasture production.

The size of plant roots is often reflective of the size of the plant above ground. When the pasture leaves are long, the root system tends to be larger and when grass is harvested by livestock, the roots shorten proportionally. The roots lost during this process become a nourishing food source for soil microbes, which then turn this dead root/carbon source into humus and then supply minerals and nutrients to the plant for renewed growth.

Roots are totally dependent on photosynthesis from the leaves to supply sugar for their energy needs. Over 30% of this sugar can be intentionally leaked out of the roots into the soil to feed the soil microbes, which in turn make nutrients available to the plant. Plants need to produce as much sugar as possible to grow their roots and feed the soil microbes, so they have access to more minerals and nutrients, and therefore produce more sugar. This system is a wonderful positive feedback loop that can enhance soil fertility and the storage of valuable carbon in the soil.

How then, does sugar production and root growth relate to grazing interval?

Overgrazing is not about how low you graze pasture but rather the interval between grazings. If this period is to short, not enough root growth will occur to supply adequate mineral levels to the plant for leaf growth, which of course means smaller solar panels upstairs, lower sugar production and therefore reduced microbial activity. What ends up happening is that the roots die back through a sugar deficit. In short, overgrazing hampers the feedback loop discussed above.

Longer grazing intervals allow the growth of larger “solar panels”, increasing photosynthesis, sugar production and root growth, which kick starts the feedback loop. Plus, with more microbes creating humus you can enjoy better water absorption, better water holding and more even soil temperatures. Larger and deeper root systems also allow for better drought tolerance. Pastures that rely on ever increasing nitrogen applications rather than supporting this feedback loop do not grow such strong, resilient root systems.

Why diversity of pasture species is so important

Diversity of pasture species in the sward improves animal nutrition because a wider spectrum of minerals is accessed by the differing plant root depths and their distinctive nutrient uptake ability. The variety of minerals, vitamins, and enzymes produced by various pasture plants provide grazing animals with a better balanced diet, and will allow the animals to “self-medicate”, choosing whatever is best for their needs. The result is healthier stock that can gain weight faster.

We encourage farmers to use a wide range of older standard varieties of pasture plants that haven’t been bred under high nitrogen regimes. Mixed swards provide diverse food sources and flexibility with back up species in changing climate conditions, resulting in gains in animal health (lower vet bills) and fewer bought in supplements (lower feed bills)