The soil thermostat

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What would it mean to your enterprise if your soils were warmer in winter and cooler in summer?

Money in the pocket as your growing seasons increase perhaps?

Producers I work with commonly report earlier grass growth and longer milking/growing seasons as their soil health improves.

There are two major drivers for this; organic matter and improved soil structure through biological activity.

If you’ve ever put your hand into a large pile of fresh grass clippings, you know it’s going to be hot.  The heat that you feel in there is being produced by trillions of bacteria feeding and reproducing (a heat generating activity!). 

Imagine soil is structured like an apartment building, with large connecting corridors, stairwells and rooms.  Good healthy soils have more airspace than they do soil!

The soils under biological management breathe freely, allowing water penetration, and improved plant access to nutrients, all while reducing greenhouse gas emissions.

When it comes to soil temperature, I often think of beautifully structured soils functioning like a strawbale house.  I don’t know if you’ve ever been inside a strawbale home, but they have the most amazing ability to hold and slowly release heat, so as temperatures outdoors drop, the house stays warm, and as temperatures increase the house remains cooler.

The same occurs in well structured soils, in Western Australia Dr Christine Jones has recorded differences as extreme as 20oC (68oF) between well managed and poorly managed soils.  In the 2011/12 drought which extensively covered New Zealand, farmers who came through the drought with good ground cover reported much lower soil temperatures than their neighbours.  We had a journalist visit in the midst of the worst of the drought and she couldn’t believe her eyes; we still had a green picking of clover, chicory and pasture, at a time when farmers in our area had their hands out asking for government interventions.  Our soil temperatures were 3-6 degrees celsius cooler than the neighbours and the bare soil in our holding yards.

Luckily in New Zealand, we don’t get the 10 years droughts that plague the Australians.

In winter this difference flips with healthy soils warmer than overgrazed, pugged, salt fertilized pastures.  What this means is rapid snow melt, less frost damage and longer growing seasons.

Just another reason to love your microbes 🙂