Much is being made of the fact that the land proposed for Rosefield Solar Farm is grade 3b and therefore “poor quality and not very fertile”. As an Agronomist and previously, 20 years ago, Farm Manager for the Claydon Estate, this is my field of expertise, so let me explain how the grading system works and why the “poor quality and not very fertile” myth is just that!
After attending a meeting with EDF and our MP, Greg Smith, local parish councillors and Buckinghamshire councillors, I have been asked to write a few words on soil classification and land use.
Agricultural land is graded into 5 bands:
The grading system is basically driven by the types of crops the land can grow.
Grade 1
This is top-quality land, it basically can grow any crops from wheat through to all veg including root crops and fruit with very few limitations. Much of it is in the east of England in the vegetable growing regions. It is the most valuable land in the country as a result of this versatility.
Grade 2
The next step down is essentially similar to grade 1 land with one of two minor cropping limitations, either in terms of crops grown or yields achieved. These two soil classes are easy working, can be travelled on at most times of the year and can accommodate harvest of veg crops late into the autumn/winter. It is worth noting that only around 20% of agricultural land fits into these two classes with none in our area.
Grade 3
The largest class 50% + of farmland fits into this classification and it is split into 2 groups:
- Subgrade 3a – “Good quality land with moderate limitations that affect the choice of crop, can produce moderate to high yields of a narrower range of crops or moderate yields of a wide range of crops.” In other words it wouldn’t be suitable for high yields of veg crops, but can still grow some of them, but is excellent for high yields of combinable crops ie wheat, barley, oats, beans, oilseed, rape, etc.
- Subgrade 3b – This is where the bulk of the soils in the solar application fit. It is also the first class that is theoretically not protected from development. It is described thus “Moderate quality land with strong limitations that affect crop choice (so no veg or root crops) and produces moderate yields of a narrow range of crops and good yields of grass.” The reason the soils around here fit into this class is because of the high clay content which therefore makes them sticky when wet and unsuited to growing many crops other than the combinable crops mentioned above. Providing they are drained, which they are, they do and can produce high to very high yields of wheat in particular, with output above the national average in most years. They also produce high yields of all the other combinable crops listed, most years, and are excellent for grass production. Being heavy deep clay soils they have a high water availability making them particularly good in a dry droughty season. In short they are very good at producing the crops that are grown on them.
Grade 4
Poor quality with severe limitations on crop choice, often flood plain, etc. Difficult to cultivate in some years.
Grade 5
Very poor quality with severe limitations. Usually restricted to growing permanent grass.
Fertility
You will note I have not mentioned fertility yet. With a few exceptions, fertility is unrelated to soil classification. A grade 4 soil can be and often is more fertile than a grade 2 soil. This is a result of frequent flooding washing fertile soil particles from upstream, etc onto it. Most of our soils have been farmed for a long time now and fertility is largely a product of farming method, not soil classification. Providing the farmer has replaced the nutrients lost when crops are harvested and has looked after the land the soil will be fertile regardless of the soil class. Clay soils naturally hold more nutrients in them and are therefore often more fertile than other types of soil.
In short, the land in the application may be class 3b, but it is perfectly suited to growing the crops and grass on it that are currently grown. It can and does grow consistently high yields of these crops and definitely makes a large and worthwhile contribution to our nation’s food security.
We should not be contemplating covering land like this with solar panels and then importing the food it currently produces.
The message we should be getting across is: Farmland for food, Roofs for renewables.
Nick Brown
As a local farmer and former soil surveyor, I fully support Nick Brown’s comments above.
It is also relevant that soil classifications need not be static; they can move up as a result of regenerative farming practices, and down as a result of bad farming practices such as over-use of chemical fertiliser or inappropriate use of farm machinery.
Thus this “infertile grade 3b” might well have been 3a or higher. This is not at all uncommon on English farms today and is the main reason that DEFRA is pushing for the widespread adoption of regenerative farming practices.