Agricultural land use: unvegetated fields result in both erosion and carbon dioxide liberation
Sunnuntai 20.10.2019 klo 19:34 - Mikko Nikinmaa
The usual way of producing agricultural products: crops, potatoes, vegetables etc., is to plough and harrow the land and use artificial fertilizers. This leaves the land uncovered by plants for a long period of time, which leaves the soil vulnerable: rain and wind can remove organic material, and the fertility of soil decreases. The major reason for soil fertility is the organic material of soil, which recovers after cultivation, if the land remains covered with plants for a long period of time. However, the present agricultural practises do not allow adequate time for soil recovery, even though in principle the land fertility is a renewable resource. The land erosion results in decreased food production to increasing human population, and the need to clear forest to food production.
The decreased land fertility is not the only problem. The plant/grass-covered soil contains huge amount of organic carbon, which is liberated as carbon dioxide when the soil is ploughed and harrowed, and the soil is without vegetation. The most pronounced carbo dioxide liberation occurs, when bog/marsh soil is dried. This increases respiration, i.e. carbon dioxide production, of soil (micro)organisms. This is particularly worrisome in Finland, as marshes have been dried to farmland, and as peat is extracted for energy production. Both cause disproportionate liberation of greenhouse gases, in fact, energy production using peat is climatewise worse than using coal.
This actually brings about the fact that if cattle is reared so that the animals feed out on grassland, the climate effect of cattle-based products is much smaller than if the animals do not feed out on grass.