From my monthly column in the Henley Standard this is the piece from June 4th.
By 2070 the world population is forecast to reach 10 billion people, so we have to find sustainable ways to feed everyone. As I mentioned in my last Farming Matters column, where I talked about climate change, synthetic nitrogen fertiliser is having an impact on our industry’s carbon footprint. The National Farmers Union has set a goal of reaching net zero greenhouse gas emissions across the whole of agriculture in England and Wales by 2040. They have asked all their members to take the pledge to ensure this happens, which I have done. I believe we and many other UK farmers are well on the way to achieving this target. There is a raft of things we can do to reduce our emissions from farming, whether it is methane from cattle or nitrous oxide from arable operations. So here I’m going to outline some of what we are doing on our farm, to ensure that we put bread on your table whilst at the same time minimising the long term effects on the planet.
The key plant food for growing crops is nitrogen, which produces the protein that plants, animals and humans all need to exist. Nitrogen finds its way into the ground from the atmosphere, of which nearly 78% is nitrogen and the plants then take it up through their roots. It is also produced in the soil by bacteria feeding on decaying plant material and animal dung. In addition, legume plants e.g., peas and beans, have nodules on their roots which contain bacteria that can ‘fix’ nitrogen, so these types of plants have their own supply. These processes are all part of the nitrogen cycle.
Medieval wheat crops only yielded about 1 tonne of grain per hectare, which farmers produced by crop rotation with legumes and applying cattle manure. This type of farming couldn’t feed many people, so with the help of synthetic fertilisers, the average UK farm can now produce around 8t of wheat per hectare. Nitrogen is the biggest input, but it is only 60% efficient. If we can improve on this by boosting our productivity, at the same time as reducing the amount of nitrous oxide that escapes from the soil by moving it less, we are all going to benefit.
Smarter farming is the way forward. We haven’t ploughed for at least 20 years, we cultivate the soil less and sometimes we plant straight into the remains of the previous crop, so as not to disturb the soil at all. Global positioning systems (GPS) are on all our tractors and harvesters now. They are a lot like your car’s sat nav, but accurate to a few centimetres and have revolutionised what we do here, particularly how we apply fertiliser. We now use GPS and satellite maps, like the one shown in the photo, to vary the amount of nitrogen applied in the fields. The red areas indicate where there is less green material and the dark green areas are where the crop is growing much more strongly. For our first trip through the field with nitrogen I will apply more to the poorer areas to encourage the plants to catch up. Later in the season the areas with bigger plants will receive more as they are going to produce more grain and therefore will require more food. The areas doing less well will have a smaller dose to reflect their lower potential. Technology allows us to be much more accurate with our fertiliser and other inputs, which reduces over or under application of these products. At harvest time the combine records the grain yield also using GPS, so we have an annual map of how much each part of the field is producing, which we can then use to fine tune what we do in future crops. We are learning all the time and looking much more carefully now as to how we can reduce our carbon footprint.