the assumption of responsibility for the welfare of the world
Topsoil is a non-renewable resource. It develops only over long periods of time, and cannot be replaced. Nutrient depletion is one threat to topsoil; the repeated planting and harvesting of crops deprives the soil of the very nutrients plants need to grow, eventually leaving the land infertile. This leads to the use of artificial fertilization, which has its own problems (see below). A greater threat to the topsoil, because it is permanent, is erosion, from water and wind. The main preventative to soil erosion is plant life; the covering of the ground protects the surface, and the root structure knits the soil in place. Traditional agriculture in the West involved plowing the field after a harvest, turning the soil over, and allowing the residue from the harvested crop to decompose in the soil as a form of fertilization. Unfortunately, that left the soil exposed from the fall harvest to the next spring, when the new crop began to grow in. Wind and rain thus carried away a portion of the irreplaceable topsoil every single year. To prevent this, conservation tillage has been developed. In general, conservation tillage is any method of limiting soil erosion during the planting and harvesting of crops. A common form is no-till, which leaves the crop residue in place after harvest, and then plants the next year’s seeds right into the residue the following spring. No-till is not a panacea, though, because leaving the crop residue requires a greater use of pesticides.
In addition to soil, which counts as a pollutant for aquatic ecosystems, there are two more categories of agricultural water pollutant: pesticides and fertilizer. Pesticides include insecticides, which kill insects, and herbicides, which kill plants. The specific plants targeted by herbicides are generally known as “weeds”, though ‘weed’ is not a biological term; it simply refers to any plant we don’t like or want. Typically pesticides are not selective, so their unintentional introduction to non-farm ecosystems will kill plants and insects that are integral parts of those systems. And once pesticides are placed on crop fields, they will eventually wash off into nearby ecosystems.
Fertilizer may not seem like the sort of thing that would be bad for the environment. After all, it only makes things grow. The problem, as usual, is the disruption of equilibrium, by allowing new things to grow in places where otherwise they would not. When a fertilizer, running off a farm field, enters an aquatic ecosystem, it contributes to the growth of plants or algae that by themselves cloud and occlude the water, thus killing certain native species, and then provide a new food source which will attract non-native species.
Modern agriculture is mostly done through monoculture, the growing of a single crop on each field, and often on each farm. This is generally done as a matter of efficiency, and monoculture is almost exclusively for sale, not consumption. (Of course, the term and the arguments apply as well to things without nutritional value, like tobacco and coffee.) Polyculture is growing multiple crops on the same field. There are several general advantages to polyculture. One is that polyculture provides a variety of nutrition; for example, growing grains and legumes at the same time can provide a source of plentiful energy (the grain) and a source of protein (the legume). Polyculture is also more resistant to the spread of disease; most diseases only affect a particular plant, not plants in general. When these affected plants are all packed next to each other, the disease spreads easily; when the affected plants are interspersed with unaffected plants, the disease spreads only with difficulty or not at all. This limits the need for chemical use to fight the disease. Certain environmental conditions will affect some plants but not all. Considering both disease and environmental conditions, polyculture leaves the farmer less vulnerable to total crop loss — and thus starvation or economic failure, depending on the nature of the farm. There are some advantages that are specific to particular polycultures (that is, particular combinations of plants). For example, including legumes in a field is a benefit to soil health, since legumes are nitrogen fixers; they convert atmospheric nitrogen to soil nitrogen. A famous polyculture of the New World is the Three Sisters, of corn (maize), common beans, and winter squash. This includes a grain (corn) and a legume (beans); the cornstalks provide a structure for the beans to climb, the beans fix nitrogen, and the squash serves as ground cover (protecting soil and soil moisture and thwarting weeds).
The majority of fresh water is used for agriculture. This fresh water is diverted from its ordinary location or destination. Most surface water serves an ecological purpose, as a source of water for all plants and animals and a habitat for many of them. If we divert this water for irrigation, it will no longer water certain ecosystems, and, just as importantly, it will inundate other ecosystems that had been drier. But even farming using rainwater has an effect on nature, as the farm replaces another ecosystem as an intermediary in the hydrological system.
The Green Revolution began in the mid-twentieth century, as a means to tackle human hunger through farming technology. The central figure was Norman Borlaug (1914-2009). Starting in Mexico, Borlaug developed strains of wheat and rice with increased yield, disease resistance, and climate suitability compared to existing strains. This was done primarily through conventional breeding. The Green Revolution has been mostly about feeding increased populations, but also has value for conservation efforts, as a higher yield per area will feed the same population with less farmland, allowing more land to be left as wilderness. On the other hand, the methods used in the Green Revolution typically increase the use of fertilizers and pesticides.
The present debate over genetically-modified organisms (GMOs) is about human health, environmental impact, and economics. The first is the weakest; there is no reliable evidence that GMOs are unsafe to eat, nor a logical reason to suppose they would be. Some organic material is toxic for human consumption and some isn’t, but genetic modification does not inherently produce toxic foods. In fact, genetic modification in the modern sense is simply an accelerated version of the breeding that has produced nearly all modern crops. The emphasis on human health among opponents of GMOs is presumably because the idea of genetic engineering makes many ordinary people uncomfortable (hence terms like ‘frankenfoods’). A stronger argument presents GMOs as a form of invasive species; introducing GMOs to a farm field creates the likelihood that this genetic material will enter the surrounding ecosystems and, like other invasives, threaten native species, with a possible long-term effect on biodiversity. GMOs are typically the result of commercial endeavor, and can be protected as intellectual property, which changes farm economics. In traditional agriculture, crops are planted from seeds saved from previous harvests; with IP-protected GMOs, seeds must be bought every year. This may seem simply the cost of doing business in developed states, but in poorer states, it can prove a prohibitive expense. Finally, while it is not an argument against genetic modification in general, some GMOs are specifically engineered to be resistant to chemicals, such as the herbicide glyphosate (sold by Monsanto as Roundup). If the crop itself is resistant to glyphosate, the field can be sprayed liberally with glyphosate without affecting the crop, which simply encourages the farmer to use more glyphosate, which will eventually run off.
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