Farmers urged to boost soil to maximise outputs

Farmers need to “reinvigorate soils with life” in order to prevent losses and maximise outputs.
According to Helen Browning, chief executive of the Soil Association, soils are being destroyed 10 times faster than they are created, with soil losses of 2m tonnes a year.
Speaking at the National Soil Symposium in Bristol last week, Ms Browning said bigger machinery and changing weather were putting soils at risk, with 15% of our land being damaged by human activity.
“Soil is the most fundamental thing and farmers have a responsibility to protect it,” she said.
Organic dairy farmer Rob Richmond is rebuilding his soils by operating a mob grazing system using herbal leys. He believes this system benefits soil structure and fertility when compared with other systems such as rotational grazing.
“In the rotational system the plant is grazed intensively, leaving not enough leaf area to produce excess sugars to benefit the soil, so sugars only go into leaf production.”
Instead, Mr Richmond believes growing grass until it flowers creates a larger canopy, enabling more sunlight and carbon dioxide to be absorbed.
“Having a diverse sward allows the herbal ley to reach flowering with little deterioration in digestibility and palatability. By this stage 60-80% of the sugars aren’t used by the plant itself, so they are put back into the soil,” he said.
Another benefit of having a large canopy is to trap carbon dioxide being released by soil bacteria, explained Mr Richmond.
“It is important to think about what’s happening underground. We need to recycle nutrients to feed the soil microbes as these work during autumn and particularly spring to release the nutrients needed to feed the rapid growth of the ley.”
Mr Richmond allows his in-calf heifers to graze the best of the mix and trample in the more fibrous material, also returning nutrients to the soil.
Grazing in this way has also doubled soil organic matter content (material from a living source broken down in soil) during the past five years.
“Increasing soil organic matter by 1% a year is the equivalent of putting 60t of carbon dioxide back into each hectare of soil a year. It also increases the soil’s nutrient holding capacity by up to 50 times. By keeping nitrates and sulphates in, there is a reduction in leaching and cleaner water enters the drains,” he said.
Improving the soil organic matter could also help farmers in drought- or flood-prone areas by increasing the water holding capacity of soil.
“A 1% increase in soil organic matter allows the absorption of an extra 125,000 litres/ha of rainfall due to the build-up of humus, which improves soil structure. The humus absorbs more rain, prevents surface run-off, and reduces flood risk and soil erosion,” he said.