Introduction to the Agricultural Revolution in England 1500 - 1850
It is argued that an English agricultural revolution happened in the century or so after 1750. One obvious reason behind the argument is the fact that an expanding population from this time on was largely fed by home production. In 1750 English population stood at about 5.7 million. It had probably reached this level before, in the Roman period, then around 1300, and again in 1650. But at each of these periods the population ceased to grow, essentially because agriculture could not respond to the pressure of feeding extra people. Contrary to expectation, however, population grew to unprecedented levels after 1750, reaching 16.6 million in 1850, and agricultural output expanded with it.
One reason the amount of food increased was due changes in the way land was used. For example, the new farming system involving the rotation of crops. In addition, food output was also increased by land reclamation. Land reclamation is when land that is normally too marshy or flooded to grow crops is drained or irrigated, making it usable.
The mix of crops also changed, replacing low-yielding types, such as rye, with higher-yielding types such as wheat or barley. The balance between usable land and permanent pasture also changed, so that more productive usable land was replacing permanent pasture. This does not mean that food supplies for animals were falling, quite the reverse, for the loss of permanent pasture was made good by new crops animals would eat, especially turnips and clover.
The most important new crop is the turnip, because it meant that the area of fallow land could be reduced. This was because one of the purposes of the fallow was to clear the land of weeds by ploughing, but a crop of turnips sown in rows could be hoed to remove weeds while it was growing. Thus fallow land was about 20 per cent of the usable area in England in 1700, and steadily declined to reach only 4 per cent in 1871.
Before this time, farmers did not know formally of the existence of nitrogen. Nitrogen is a natural gas that acts as a fertilizer. Nitrogen can be found in animal manure. While farmers used manure to fertilize the soil, the scientific reasoning behind this was not known. However, during the agricultural revolution the science of farming changed. Prior to the Agricultural Revolution available nitrogen was conserved by feeding animals in stalls, collecting their manure (which is rich in nitrogen), and placing it where it was needed. Also, most importantly, new nitrogen was added to the soil using legumes - a class of plants that have bacteria attached to their roots, which convert atmospheric nitrogen into nitrates in the soil that can be used by whatever plants are grown there in the following few years.
Legumes had been sown since the Middle Ages in the form of peas, beans and vetches, but from the mid-17th century farmers began to grow clover for the same purpose, and by the 19th century had dramatically increased the quantity of nitrogen in the soil available for edible crops, like grains. This new system of farming was remarkable because it was sustainable; the output of food was increased dramatically, without endangering the long-term viability of English agriculture.
A second reason why we can claim an agricultural revolution in the century after 1750 is that as each agricultural worker produced more food, so the proportion of the workforce in agriculture fell. This falling proportion of workers in agriculture enabled the proportion working in industry and services to rise: in other words improved agricultural production made the industrial revolution possible, and many would regard the industrial revolution as the beginning of the modern world.