One of the central metrics or foci of much modern commercial agriculture has been yield per acre , the measure of the amount of a particular crop capable to be produced by an acre of land. A drive to increase yield has claimed in technological innovation and increased production.
However, yield per acre is only one of many ways of measuring the success or effectiveness of an agricultural system, and when we focus on it at the expense of other metrics, we risk optimizing yield while creating a wide range of hidden costs, some of which can be catastrophic.
Quantity vs. quality
One of the most obvious thing to suffer under a system that optimizes yield at the expense of all else is quality. Quality can be obvious when talking about a crop that people directly eat in whole form, especially fresh fruit like strawberries. But in other cases, such as feed corn, forage crops, or crops that are used as raw materials for refining, such as processed into oil, starch, or sugars, it is less obvious.
The areas in which quality typically suffers most is in foods that are not directly consumed in whole form, because the quality is less obvious. In the case of animal feed, the animals are typically not monitored for their choice preferences (animals often do exhibit preferences for one batch of feed over another, if you give them the choice and carefully observable them), so even if the potential for monitoring quality is there, it typically is not done.
Quality thus suffers. One example of a way in which quality can affect humans, even in the case of animal feed, is through fat profile. For example, corn is widely used as an animal feed in the US For example, open-pollinated corn (the traditional form of corn where each plant is genetically unique and the seed is collected and re-planted the next year) has a healthier fat profile, and greater antioxidants, than hybrid corn, and produces animals with a healthier fat profile, which are thus healthier to eat. But because hybrid corn produces a greater yield per acre, optimizing for yield causes quality to suffer — and in this case the quality is in the meat or dairy produced from cows fed this corn.
Focusing on yield per acre can also result in increased harm caused to the environment by the farming system. For example, most traditional crop systems have hedgerows or buffers of trees between fields of crops. Eliminating these can give a small amount of extra land on which crops can be grown, and can also slightly increase the yield along the borders where the trees would partly shade the crops.
However, eliminating these wild border areas can destroy biodiversity. As the trees are better at holding soil than annual crops, removing them can increase erosion and soil loss. The wild areas can also be buffers for natural predators of insect pests, and removing them can increase the need for insecticides, which themselves have negative environmental impacts.
Removing buffers along streams or drainage ditches is particularly damaging, as these buffers take up nutrient runoff from agricultural fields, and also reduce the risk of flooding downstream. Flooding can damage other crops downstream, and nutrient pollution, including harming the environment, can also damage fishing industries downstream. The result, when viewed holistically, does not even make sense from an economic perspective.
Yield per acre is only one measure of the success or health of an agricultural system. Attempting to optimize yield without considering other factors like quality or environmental impact will inevitably lead to hidden costs, and a decline in both environment and the quality of your crops. The most economically and environmentally sustainable model for agriculture is one that looks at yield per acre only as one factor among many, balanced against other metrics, to holistically assess the success or health of an agricultural operation.