I recently drove across Iowa on I-80 and stopped at the rest area near Casey, Iowa. They have an interesting display outside in front of the building about Iowa Agriculture and the amount of soil loss that has occurred. According to this display the average depth of topsoil in the year 1850 across Iowa was 14 inches. In 1900 it had decreased to 11.5 inches. After another 50 years it had dropped to 8.5 inches and in the 50 years from 1950 to 2000 it had decreased another 3 inches to 5.5 inches. If our rate of loss has stayed steady over the last 18 years the topsoil depth should now be at 4.5 inches. If this rate continues our topsoil will be depleted by 2093. Assuming these trends are correct, this is a rather scary thought that in another generation, the topsoil would be gone. Actually, in areas that are less erosive there would still be topsoil, but this is using average numbers.
It is a fact that yield is directly related to depth of topsoil and organic matter levels in the soil. If topsoil is not as thick, organic matter would be decreased also. It will be difficult to sustain our yield levels or increase yield levels as the trend has been, if this continues.
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Farmers need to focus on ways of farming that will reverse this trend or at the least slow the rate of loss that has been occurring over the last 100 plus years. There are many practices that can help. Improving production in those areas that are already severely eroded should be considered. The picture to the left shows reduced growth on the eroded hillsides.
Terraces can also assist in reducing erosion, however, where topsoil is already thin, building terraces decreases production and exposes more subsoils.
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See the picture of a recently terraced field in SE Nebraska. Both of these fields can be amended and production improved if gypsum is applied. Nutrient availability is improved, root growth is greater and water infiltration is enhanced.
Use of no till practices, cover crops and crop rotations that include alfalfa and/or clover can also be effective in decreasing soil erosion. Using gypsum with any of these practices will improve production plus decrease runoff, keeping our water and streams purer. Including products such as humic acids and fulvic acids may also be helpful in boosting the yields from these soils since there are less of these available in our soils as our organic matter becomes depleted. These products are available through Soil Solutions and our affiliated retail dealers. You may learn more about humic and fulvic acid on our website. “Improve your soils and the yields will follow” is our tagline at Soil Solutions. Give us a call and we can discuss your soils and how we may make them healthier and more productive.