System design and rotations
It’s hard to look at soil health in isolation. Almost every business decision you make impacts your soil; the crops you choose; the machinery you use; your stocking densities. All your actions will either deplete, maintain or enhance your soils. So, if you want more productive, healthy soils you may need to take a step back and look at your farm as a whole.
Put simply, farm systems fall into those that are stock-based, mixed and stockless. Whatever your system, there are things you can do to make it more soil-friendly. Introducing cover crops and green manures will build your soil fertility on a stockless farm. Whilst extending the rotation and bringing in a greater variation of crops with different rooting depths will improve soil structure and workability. Planting a leguminous herbal ley would benefit soils in stock-based systems. On a mixed farm, you might decide to extend the fertility-building grass ley stage of your rotation, so that your soils are more productive for your cash crops. Each year, consider tweaking your system to benefit your soil.
The trend in farming systems since the 1970s has been towards greater and greater specialisation, with most farms now focusing on a single enterprise. This may suit you and your farm, but if you are considering diversification there are some interesting business models that can benefit both your soil and bottom line.
For centuries, our arable farming systems were based on the Norfolk four-course rotation. Rotations consisted of two cash crops and two crops to feed livestock and would have included legumes for fertility building, and livestock to graze and provide manure directly to the field.
The last sixty years have seen many farms replace the fertility building phase and livestock with artificial fertilisers. While allowing much shorter rotations, this has had unintended consequences for soil organic matter (SOM) levels and soil structure. However, where crop rotations tend to be longer we are seeing higher levels of organic matter. A recent review of studies from all over the world demonstrated that organic farms store, on average, nearly 3.5 tonnes more soil carbon per hectare, and release less nitrous oxides, than conventional farms.