Posted Online: Dec. 02, 2012, 6:00 am
The sustainable agriculture movement
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By Dan Lee
The past two weeks I have noted both the phenomenal increases in the productivity of American farmers and some of the costs associated with this agricultural revolution, among them ground and surface water contamination and soil erosion.
All is not doom and gloom, however. The sustainable agriculture movement, supported by the work done by scientists at the Leopold Center for Sustainable Agriculture at Iowa State University and similar work done at the University of Illinois, the University of Minnesota and elsewhere, has made significant progress of diminishing the environmental costs of the productivity revolution.
As noted last week, extensive use of artificial fertilizers containing nitrogen, which joins with oxygen to form nitrates, can result in increased nitrate levels in both ground and surface water. High levels of nitrates in drinking water can cause severe health problems in infants.
Excessive use of artificial fertilizers can result in increased nitrate and phosphate levels in streams and rivers that empty into bodies of water such as the Gulf of Mexico. There they contribute to eutrophication -- the excessive growth of algae which, when they die and decompose, deplete the oxygen supply to the detriment of fish and other species.
The problem here is excessive use of artificial fertilizers. If farmers only apply the amounts their crops need, runoff is not a problem. The good news is that technologies are now available to ensure that artificial fertilizers are only applied in the amounts needed.
A key element in this equation is the global positioning satellite (GPS) system, which enables locating geographical coordinates within a few feet (or in the case of expensive systems, within a few inches). This accuracy enables subdividing fields into grids, using GPS to identify the coordinates of the grids.
The next step is collecting soil samples from each grid and sending them to a laboratory for analysis. This determines exactly which nutrients are needed in each grid and in what amounts. The information is then entered into a computer program.
The third and final step is using a computerized fertilizer spreader hooked up to GPS, which will indicate precisely which grid they are in. The computer then adjusts the application rate of the spreader so that only the amount of fertilizer that is needed is applied. The result? Less money spent on fertilizer and less nitrate and phosphate runoff in streams and rivers. It's a win-win situation.
Another important part of the sustainable agriculture movement is Integrated Pest Management (IPM). When ag chemicals first came on the scene, farmers had a tendency to pile on plenty of them to make certain that they got rid of the pests and weeds threatening their crops. The result was that they used more than was really needed with the excesses contributing to surface and ground water contamination.
There's a better way of doing it. By carefully monitoring the life cycles of insects with thermal indicators tracking when they are likely to emerge, pesticides can be applied when they can do the most good, reducing the amount needed. Crop rotation can also contribute to better control weed and insect control, as well as help maintain the fertility of the soil. Also of significance are new herbicides and pesticides that decompose in a relatively short period of time, thus lessening the impact if they end up in ground or surface water.
There's a lot more that is happening -- tillage practices that reduce soil erosion, ways of controlling diseases in livestock without lacing feed with antibiotics, and much more.
The last half of the 20th century witnessed phenomenal increases in crop yields. I am persuaded that this century will be the century of sustainable agriculture, a movement that will be every bit as significant as the revolution in productivity. We live in fascinating times.
Dan Lee teaches ethics at Augustana College; firstname.lastname@example.org.