A revolution for intensive farming
The world population is seven billion and climbing. As a farmer this is thrilling news because, as the demand for food grows, I can imagine myself paying off the overdraft and acquiring a bigger better newer tractor. Such are the things that farmers fantasise about. Then I come back to reality. Over the last few years my yields have not increased due to dry spring weather, the price of fuel has more than doubled, fertilizer has tripled and the price of that new tractor is up thirty per cent. While it is true that food prices have shot up so have my costs, so I am no further forward.
Currently our food supply depends on oil, without oil we do not eat. The current, let alone predicted, population has boomed on the back of oil. Without diesel my tractor doesn’t work nor do the lorries deliver food to the shops. Without natural gas there would be no fertilizer, reducing the yield of my crops by half and most of the rest of the yield relies on chemicals which are derived from oil. While oil and gas are not about to run out, we hope, the demand is rising and so is their cost. So what can I do about this?
I have to produce more food with fewer resources and less land, we have to make space for wildlife too. The politicians call it sustainable intensification, aiming to cut agriculture’s greenhouse gases while improving biodiversity at the same time, but can it be done?
Key to all of this is carbon, but not in the way you might think; it is organic carbon, or humus. For years farmers have been cultivating their soils to create a seed bed, mainly by ploughing but more recently by shallower cultivations which are cheaper and faster. The problem is that when soil is exposed to the air organic carbon in the soil is oxidised and turned into carbon dioxide, destroying precious humus. Humus is locked up carbon and it has been suggested that if all the carbon dioxide released by ploughing were still locked in the soil then we would not have a greenhouse gas problem. Humus has almost magical properties in the soil, giving the soil strength to resist heavy machinery yet keeping the soil crumbly and open, it acts as a sponge improving water holding capacity increasing drought resistance and slowing down water infiltration. It also allows me to grow my crops withoutm having to create a seed bed, saving a huge amount of money and resources; this is the magic of no till farming.
To increase humus I must encourage biological activity in the soil. The key principle is to disturb the soil as little as possible; if you move the soil then you lose humus, damage your worms and their burrows, kill beneficial beetles and destroy fungal hyphae and generally upset the natural processes within the soil. The soil should never be bare; during harvest all the straw is chopped and spread over by the combine to provide mulch. This suppresses weeds, reduces evaporation and retains moisture in the soil, with the help of the spongy humus, for the new crop. If it pours with rain then the residues protect the soil from erosion and the increased porosity helps the ground dry more quickly.
I grow cover crops over winter before any spring crops because living plants feed the soil organisms which then deliver nutrients to the plants. I want them to capture nutrients which would otherwise be washed away over winter and I want their roots to help bind the soil together reducing erosion and the old decaying roots also provide channels for the new plants to follow.
The next requirement is to feed the worms with compost, farmyard manure and crop residues. The worms pull the organic matter into the soil where a multitude of soil organisms feast upon it slowly breaking it down into humus. When the worms make a burrow they glue the soil particles together stabilising the soil, increasing its porosity, and their worm casts are full of plant nutrients. Over a year the top inch of my fields is almost entirely worm cast. The worms cultivate my soils for free and I need less fertilizer as a result.
An unforeseen benefit is an increase in biodiversity on the farm. If you encourage the bottom of the food chain, such is the lot of a worm, then animals higher up also benefit, and an uncultivated field is more like a winter stubble which helps many of our farmland birds.
Finally we come to my no till drill which cuts a narrow slot in the soil, drops in the seed and gently pats in down. If the slot is not covered then the seed will dry out or be eaten by slugs or birds, so it is critical that the soil is crumbly and friable. The final benefit of a no till drill is it only needs a small tractor to pull it because it is not moving much soil, reducing my fuel bill and massively reducing the amount of money tied up in machinery.
So does no till address the contradiction of sustainable intensification? I am producing the same amount of food using a lot less resources which is a step in the right direction, but I am still totally reliant on the finite resources of oil and gas to grow my crops and yields have not increased for the last ten years so there is still a mountain to climb if we are not to run short of food. And what about that new tractor? Well I do not really need it now that I have sold all my cultivation machinery so I will just have to make do with less of an overdraft.
Andrew Bott is an arable farmer managing thousands of acres in Hertfordshire who was also a tank commander in the first Gulf war.