The importance of agriculture seems obvious for two major reasons:
We cannot escape these reasons and both create environmental issues.
Everyone has to eat and now that there are so many of us food production is crucial.
In developed economies it is easy to take agriculture for granted. There is food in the shops in all manner of varieties and the majority of people are well fed.
Except that thanks to a combination of eating more [average global per capita calorie consumption has increased by 20% since 1970] and there being more of us [global population has almost doubled since 1970], agricultural production has a huge task.
Each day humans consume 1.7 x 1013 kcal calories, most of it from grains [wheat, rice and maize].
This will sound like a lot and it is.
It amounts to roughly 4 billion tons per year.
At its simplest this tonnage comes from the ability of plants to use energy in sunlight to convert nutrients to carbohydrates via photosynthesis — what ecologists call primary production. Agriculture and forestry now divert over half the global net primary production [NPP] for our direct benefit.
Half of what the land plants make we use.
Not only do we use half of NPP, we have converted almost 12% of the earth’s land area for cultivation. Our food needs are so great that we cannot rely on nature alone, rather we channel NPP into plants that we can readily use.
At least 17.3 million km2 of the land surface [an area almost twice the size of the US] has some sort of crop grown on it. And most of this land was cleared of native vegetation to enable crop production.
forested land cleared for cultivation on the tablelands of New South Wales, Australia
This clearing and cultivation, together with livestock production, is an impact that is arguably far more significant than greenhouse gas emissions or the pollution of the river. The widespread appropriation of land and water for agriculture is up there with the meteorite strikes of the past, certainly it has helped trigger the latest major extinction event [biodiversity loss].
Not bad for an invention less than 10,000 years old.
So the importance of agriculture is also about this appropriation of land and net primary production. Agriculture generates a land use change that often alters the carbon, nutrient and water cycles. In turn this affects the ability of nature to deliver the services we seek.
Even though 10,000 is a blink given the age of the Earth, not much happened with agriculture for the first 9,800 of those years.
There are a few small to medium-sized civilizations that were able to prosper, some of them famously so such as ancestors of the Shona people who built Great Zimbabwe, one of the few major stone monuments in Africa outside of Egypt.
There would also have been many smaller successes but as Jared Diamond describes, almost all of them collapsed because they ran out of food or water. In other words, agriculture failed.
So the importance of agriculture is at least the essential provisioning of people who spend their time doing things other than hunting or gathering food, and these days that is just about everyone.
The really remarkable thing about agriculture is its own revolution from small-scale, modest production that required human labour to modern yield powerhouses. And this has happened in the last 200 years, triggered by the arrival of fossil fuels, especially oil.
Oil and internal combustion engines not only supported land clearing and tillage of soil but also allowed the manufacture of fertilizers at scale.
The history and a large part of the future of agriculture is about inputs.
Most agricultural production systems rely so heavily on external inputs of energy and nutrients that without them they would collapse and net productivity would not meet demand.
Ask Alloporus explores the environmental issues with the importance of agriculture in more detail given
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clearing of forest for agriculture, NSW Australia
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