Despite our tendency to streamline many processes by reducing diversity, it seems we are fighting a losing battle. Just as we increasingly realize that ecosystem-wide biodiversity is important, it is time to recognize the same trend in man-made systems. Yes, it is convenient to raise monocultures – from crops to poultry to fruit trees. But the side effects may drown out the ease and low cost. In fact, a study in Frontiers in Ecology and the Environment reveals that crop biodiversity has beneficial environmental effects.
Using historical data across a variety of watersheds, the study looked at basic agricultural practices over the past century. With increased industrialization and movement away from smaller agricultural operations, the average farm has become twice as large and relies on both mechanized equipment and chemicals – fertilizers and pesticides – to become more efficient. As a result, agriculture has a greater environmental impact.
One problem with current intensive farming methods is agricultural runoff. Fertilizers are used widely to ensure rapid and uniform growth. But after encouraging plant growth, these compounds leach through the soil and end up in both groundwater and field drainage. Once in streams, rivers, lakes, and coastal waters, the key nutrient in fertilizer – nitrogen – causes eutrophication. Aquatic plants and plankton grow and reproduce rapidly, choking out other organisms and depleting dissolved oxygen levels. As a result, many other plants and animals die.
One alternative is selecting organically grown products, where farmers have chosen not to use fertilizers and other chemical treatments. But the organic movement is still relatively small and does not address solutions for conventional producers.
The other issue is crop diversity. When the economic return per unit of crop has dropped, it becomes necessary to grow more and more to break even. That’s where monocultures come in – they require standard planting, treatment, and harvesting schedules, increasing overall efficiency. But the environmental effects are less obvious.
When a single crop is grown over a large area, there is less interaction with other vegetation. Traditional small fields are surrounded by other plants – from flowers to hedges to small areas of trees. These neighbouring plants take up some of the agricultural runoff and mitigate the effects of chemical treatments. With large uniform fields, more runoff chemicals make their way into local waterways. Modern fertilizers are also more concentrated, which may amplify the effect. Crop rotation might also help, with different crops using varying amounts of nitrogen from year to year.
Unfortunately, farmers are caught in the middle of this problem. Once a farm reaches a sufficiently large size and focuses on a single crop, it is difficult – and economically unfeasible – to break the cycle. Then again, fertilizers and other treatments are also expensive but increasingly necessary as the soil is depleted and pests get a foothold. But some old-fashioned principles might help lead back to a more sustainable approach. Decreasing individual field sizes is a start. Any expansion – even by inches – of field edges and buffer zones would support other species. Plant native grasses and other plants along the buffer zones. Consider crop rotation – it has worked for millennia.
But more than relying on the actions of individual farmers, it is important to look at overall agricultural policies. Making agricultural more sustainable and less environmentally damaging should be a priority. Surely this is a better approach than simply throwing subsidies and modified chemicals at the problem.
What can we do at an individual level? Choose locally grown produce whenever possible. Buy organic. Look for products from small-scale farms. Talk to the store manager. Write to your local government representatives. It won’t be quick or easy, but we have only relied on such artificial and intensive methods for less than a century. So it should be possible to take a step back, if it means maintaining a liveable environment.
Photo credit: Joe Nicora