Last week I visited North West Scotland on a short holiday. It is a land of stunning open spaces, glaciated volcanic lumps and mountains interspersed with wide valleys, green and lush at this time of year. The green vegetation is not grass though, but a huge mix of species of plants that like the wet acid soil conditions and mild climate. There are a few sheep farms, but everywhere, even in the high hills there are ruined farms, crofts and shielings (seasonal settlements for grazing animals). The population used to be much greater, before the industrial period with its clearances and emigration. The whole area is a model for what will happen as smallholders around the globe abandon their plots and move into cities for a “better” life. This is the reality of rewilding, it has been going on a long time in the Highlands.
Northern Latitudes hold a huge potential for the next phase of agriculture. There are huge reserves of carbon and nitrogen in the peaty soil under the vegetation. As the planet warms up there is a risk that these soils and the huge tundra areas of Canada and Russia will release even more methane and Nitrous Oxide than the sparse animals that graze there.
In the Bronze Age 5-6000 years ago much of upland Britain was farmed, as shown by the settlement ruins and field boundaries on top of Dartmoor and Exmoor. The village people on Skara Brae, Orkney at 590 North grew cereals. The reason was the climate was +20C warmer than the twentieth century. It is predicted that we will have accidentally achieved a similar or warmer climate within a few decades unless we find a way to reduce carbon dioxide emissions.
At the same time we expect to lose arable land to climate change and urbanisation further South. The growing area is moving North with climate change. If we try breaking new ground in the traditional way with the plough it would be a disaster as it would release the bound up carbon and nitrogen as methane and nitrous oxide, further exacerbating the greenhouse gas effect. It would also cause soil erosion and biodiversity loss.
We need an alternative way to use the soil resource for food production that does not disturb the deep soil. How about draining and grazing it ? This would almost certainly have been how the Bronze Age settlers would have started. Once the sward had been eaten or burnt back they would have been able to use simple draft animals (probably human) to drag an implement across to scratch the surface and sow some saved seeds. They would have had to weed the crop by hand as early ploughs did not bury the surface trash well if at all.
If that sounds familiar it is because it is min-till without weedkiller and modern plant varieties. It was subsistence farming, probably in parallel with hunter gathering. The labour must have been back breaking but if the alternative was starvation it would get done.
We can now use the new technologies of robotic tractors with shallow tools to till and weed much as humans used to do. We can dispense with heavy tractors causing soil compaction and use lightweight autonomous tool bars to continuously patrol the fields disrupting the weeds. The same robots could be used to distribute small amounts of fertiliser at appropriate moments in the growth cycle and remove weeds without chemicals. Appropriate moments would be based on plant needs and weather status determined by web connected algorithms. Applying fertiliser when rain is not predicted could have a major impact. Dry soil emits little nitrous oxide which is a major greenhouse gas. Emissions are growing rapidly according to the latest IPCC report as farmers around the world increasingly use artificial N fertiliser to increase yields of crops. Even more serious is the pollution of river water leading to dead ocean zones which also emit huge amounts of N2O.
We need cover crops and rotational grazing to suppress weeds and restore fertility without exposing the soil to erosion. The question arises what do you do with all the grass and clover ? Maybe feed it to livestock ?
Switching the world to a lower meat diet might reduce methane emissions but it will lead to more N pollution and that could have an even more disastrous effect than we have currently. This could N badly.