How do you measure biodiversity and why does it matter?

We haven’t actually been measuring biodiversity changes on the farm, as such, but there have been pretty dramatic improvements. The diversity in the pastures is remarkable. Many of the herbs we now see commonly were previously killed by the herbicides we had used to reduce thistles, nettles and docks.

On the cow pats, there are 5 types of fly and 2 types of beetle rapidly colonising, burrowing and incorporating cow pat material into the soil. The parasite drenches we previously used on our cattle kill these insects or their larvae, breaking the nutrient and carbon cycles. I used to panic about the farm becoming infested with difficult to control docks, but I needn’t have worried as the Green Dock Beetles and their larvae are having a devastating effect on the docks, keeping them in check – nature keeping everything balanced.

This is why high biodiversity matters. It does take time, but when you work with nature rather than against it, nature works for you and it works for the planet too.

Recently we uncovered historic soil data that had been locked away in the James Hutton Institute’s vaults in Dundee. The soil samples were collected from thousands of sample points from all over the farm, excluding the woodlands, over the 25 years as we transitioned firstly to organic then to regenerative farming. While there was variation up and down over the years the overall trend of the soil organic matter for the farm was upwards.

Soil organic matter is a crude measure of the health of the soil. In soils that have had crops grown on them year after year, the soil organic matter levels are in the order of 1 or 2 percent, they’re pretty well burned out. Roughly 68% of soil organic matter is carbon, so if your soils are increasing in soil organic matter they are also increasing in the amount of carbon they are locking up.

Dairy farms in the west of Scotland are generally much higher in soil organic matter than the arable farms in the east, usually around 6-8% organic matter. Ours started at 11%, which was quite high and I wasn’t expecting much of an increase. In fact our soils now average almost 14% organic matter. To calculate the carbon in the soils is quite complicated as we’ve to estimate the carbon in the lower levels of soil and allow for carbon migration and bulk density changes over the period.

But that done, the data says we have been locking up carbon at a rate of around 5 tonnes of carbon per hectare per year. That takes us to beyond net zero.

 

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