Arquivo de etiquetas: Sistemas Agrícolas

Sustainable Food Supply and the End of Hunger II

Farm Systems, Ecology, and Food Security

One of the challenges of addressing the food security issue is how varied the farm systems are around the world. This isn’t surprising, the world itself is incredibly varied in what’s grown, where, how, climate, soils, topography biodiversity, all have an enormous effect in shaping farm systems. And because of that, there is certainly no single answer to how farms can become more productive for example. Or how local populations can become healthier in what they eat. Different places grow different foods. They eat different foods. They face different climatic and agronomic challenges. And, part of our proper, problem-solving our diagnostics and our solutions for the issues of a sustainable food supply, depend on us understanding, in detail, how these farm systems differ around the world. Well to do that, let’s take a look at the world in the big picture to get a very macro sense of how farm systems are shaped and how they differ in different places in the world. Consider the land area of Earth in its entirety.

1021There are about a 130 million square kilometers of land on Earth. And of that, a remarkably large proportion are already taken by humanity for human needs. Agriculture, meaning, both farmland, arable land, used to grow crops, and meadows and pasturelands, grasslands, used to feed animals, constitute together around 50 million square kilometers or roughly 40%, a little under 40% of the world’s total land area. This by itself is rather astounding. One species of the millions on the planet has requisitioned land for us to feed us. And when we discuss the declines of biodiversity, the first thing to keep in mind is how much of the output of food on the planet. How much of the photosynthesis on the planet is taken for human need, and how much that leaves the rest of the biosphere behind and threatened by this human grab for the planet’s primary production of, of food. So, 50 million square kilometers used for arable and pastureland, roughly of that, 14 million for arable, that’s for croplands. And roughly 34 million square kilometers for meadows and pasturelands. So, the farmland itself accounts for a little over 10% of the world’s land area. Pastures, much bigger around a quarter of the total land area on the planet in grassland regions used to graze animals. Another 39 million or so square kilometers is for forests. Many of those forests are managed forests, plantations for pulp and paper for example, for timber for logging. Some of those forests are not managed the boreal, vast boreal forests in the high latitudes as an example.

The forests in total account for another 30% or so of the Earth’s land area. The remainder is another roughly 30% it’s another 41 million square kilometers. A lot of that is desert. A lot of that is uninhabitable. A few percent of the world’s land area’s in our cities, where half the world’s population live, but we’re so densely settled in the cities, that the cities themselves, the urban extent only accounts for a few percent of the, 130 million square kilometers. Most remains either in the form of agricultural land, forest land or deserts and uninhabitable land areas. You’re looking at a map now, of where the agricultural land is. Both the crop land and the grazing land. And the colors here are showing you places where the cropland is very concentrated. Not every place where land is used to grow crops, but places where a very high proportion of the land in that area is actually arable or cropland, that’s the green shaded areas.

It’s the midwest of the United States, it’s parts of western central, and eastern Europe. It’s much of China and India. In Africa and in in South America you see land that is mixed in grazing land and in cropland. The drier areas tend to be places where food crops can’t be grown with high productivity.  If the rains fall below a certain amount during the rainy season, then crops can’t grow at all. And to the extent that people live in those environments, that they’re not desert, but rather are arid but not extreme hyper arid regions, they are places that are used for grazing animals. So livestock production tends to be in the drier areas. Nomadic populations, who are pastoralists full-time for their livelihoods, often with no crops at all, are living in places just on the margins of the desert. In Africa you see these grazing land areas just south of the Sahara Desert. In the top half of the African continent.

1022 And then around the Kalahari Desert in the southern part. The forests are shown in the next graph. And there are two major forest areas to keep in mind. First is the forest areas around the Equatorial belt. These are the rainforests. The Earth’s climate is of course providing most solar radiation at the equator. It’s the warmest at the equator. The land eh, is heated. Air masses rise and provide continuous rainfall or heavy rainfall, I should say, in the equatorial regions of the world. And that provides the climatic base for the three great rainforests of the world, the Amazon, in South America, the Congo Basin in Africa, and the great rainforests of the Indonesian Archipelago in Southeast Asia. That’s the band around the equator. Then you see the other major forest region which is in the high latitudes. The boreal forest for example in, across the vast Eurasian land mass, and across Canada. Many of these forests are being threatened especially today the rain forests. Because these are all areas where populations are encroaching for a variety of reasons. Either to clear the rainforest to make way for pastureland and for cropland. Or poor people encroaching on the forest for fuel wood and for other goods and services that they can procure from the forest. But sometimes in such great numbers that they are deforesting in an unsustainable way. This pattern of where the cropland is and where the forests are, you can see is very deeply rooted in the ecological conditions. The climate, including temperatures, rainfall, the topography. The shape of the land, whether it’s steeply sloped and not possible to farm or whether it’s flat land in plains much easier and more productive to farm. Whether irrigation is feasible, because there is ground water, or rivers nearby that can be used for irrigation. Whether the soils are adequate. And the range of soil types depending on the the underlying geologic conditions also shape the farm systems. It’s worthwhile for us to take one deeper look in one part of the world, to see the geography shaping the farm systems, shaping the societies in effect in these agricultural regions. And, and that’s in Africa, where we can see very, very clearly how the distinctive characteristics of climate cause very distinctive farm systems and very distinctive economic results as well.

1023This is a map. Quite a beautiful map, I think, of the various farm systems in Africa. 14 major agro-ecological zones. Each one a specific kind of farm system. Perhaps it’s a good idea to decipher this map in, in stages starting at the equator. In the large green area, right it, at, at the center of the African continent. That’s the Congo Basin, that’s the great Congo rainforest. And rain forests are very particular when it comes to agriculture. Very difficult to farm, often. soil, nutrients are bombarded by heavy rainfall. If trees are cleared as is sometimes done to try to make farms, it often is the case that the soil nutrients which were up in the trees themselves rather than in the soil are quickly depleted and it turns out that the land is not suitable for intensive farming. And not even suitable for pastoralism or for livestock management. If you, we move from the equator we come to different farm systems graded, to a very important extent, according to how much water is actually available through rainfall and other other resources. Take a look at West Africa, for example, just above the Atlantic Ocean. And right along the coast, the entire coast, of West Africa is a still wet, though not rain forest region which is ideal for tree crops. For the cocoa plantations of Ghana, the rubber plantations of Ghana, Benin, Togo and Liberia. So this is a climate not of annual grain crops but of tree crops because of its humidity and its ideal circumstances for tree crops. Move north of that, away from the equator. You move into an environment where there is a rainy season. But, the farther north you go into the northern hemisphere. The drier is, are the conditions and the shorter is the rainy season. So, just north of the rubber and cocoa plantations, one finds what is called the root crop systems. For example, where cassava is grown and other tubers and root crops are grown in this relatively wet environment. But not wet enough to support cocoa trees or rubber trees. Move just north of that and then you’re into a grain belt. For example where maize or in the United States we call it corn is growing. This is now a, a part of Africa where instead of the year-round rainfall of the equator, you have one rainy season which may give a growing season of 150 days for one crop of maize per year. it can be rather productive if the topography and the soils are right, and if the rains are good. It can be a disaster if it’s a year of bad rainfall. And there is relatively high variability in these places. And in the African context, at least, relatively low use of irrigation. So a dependency on the variation of the rains. Now as you continue the march north from the equator, towards the north pole, the rainy season gets shorter and shorter. So after the band of grain growing region is another farm system and this is a farm system that mixes crops with livestock. The livestock to graze on the grasses, the crops to capture a short growing season. But now it has to be crops that are pretty resilient to short rains and even to drought. Those are sorghum and millet for example. So, we have passed through the maize region into the sorghum and millet region combined with more livestock. And this is the so-called agro-pastoralist zone. Because it’s both agriculture and pastoralism. Move a bit north of that and you move into a range that is an all pastoralist region. And these are places often of nomadic populations such as the Tuareg in Northern Mali. The population densities are very low. The populations are nomadic, because they have to follow the rains. And as the rains move throughout the season the grasses spring up for short periods of time in these dry environments. And the animals better be where the grasses are so the animals move around. Also the  nomads move across national boundaries. No one told the animals and no one told the rain this is Mali, this is Chad, this is Niger, stay in your place. And these artificial boundaries that have been put first by the imperial powers. And now as part of our political world. Have wreaked havoc on the pastoralist traditions that find themselves cut off from their family, neighbors, and their grasslands across a political boundary that has no ecological sense. Now, consider one step north of the pastoralist lands and in you’re in the Saharan Desert. We have, er, I should say Sahara because it’s the desert. because, so, in, in, in fact, you’ve entered the desert. And we have seen the graded transition by latitude band from a rain forest to a tree crop region, to a root and tuber crop region, to a grain region to a agro-pastoralist region to a pastoralist region and then to the desert. It’s not surprising this is complicated. It’s complicated for countries to manage this diversity it’s complicated when populations like pastoralists need to move across boundaries. It’s complicated to get international agreements on what to do about issues of climate, or energy, or food production, when we see these strong variations of farm systems across the regions. It’s very hard, often, for people to speak with each other and to understand the problems and the stresses that are unfolding. This is one of the reasons why the world has failed to comprehend challenges like the crises of the Horn of Africa and the ongoing crises of the Sahel. These are agro-pastoralist regions, or in some cases, pastoralist regions only. Very poor. Very much dependent on rainfall. Suffering the burdens of climate change, instability of rainfall, rising populations, falling trend in total precipitation, increasing hunger. And, as a result, increasing instability and violence We need to understand these farm systems, where they are, how they vary around the world, if we are to achieve sustainable agricultural yields that can feed and keep populations healthy in the future.