Do you base farm decisions on soil quality? Clay Mitchell does, as he deems it the ultimate resource. That’s why he redistributes accumulated topsoil across parts of his family’s 2,500-acre Buckingham, Iowa, corn and soybean operation. Besides building long-term soil productivity, moving surplus topsoil from valley to hilltop also boosts land value.
Known for leveraging technology to advance conservation and efficiency, Mitchell’s farm-wide local-area network (LAN) streamlines precision-elevation mapping, soil-quality metrics and results tracking (see yield map and chart/slide 49).
Mitchell, who also runs a land-investment firm, scrapes black gold from surplus topsoil areas along grass waterways to achieve a more uniform goal of 8 in. topsoil on the farm he operates with his great uncle Philip. This adds roughly $6,000/acre to eroded areas (see sidebar) for a cost of $810/acre (labor and machinery).
Mitchell used a prototype of Deere’s Surface Water Pro Plus and iGrade advanced ditching technology, inspired by the next-generation advanced landforming technologies of David Cox and
, Broughton Boydell, both Australian farmers who have commercialized landforming products, called OptiSurface (http://www.optisurface.com) and Precision Cropping Technologies (see http://pct-ag.com/). A giant step beyond laser leveling flat fields, landforming across many thousands of acres of rolling terrain precisely optimizes water infiltration to avoid ponding and overly dry areas.
Check the math
The $6,000/acre increased farmland value from Mitchell’s strategic earthmoving accrues to 17.8 acres of low-value knolls with eroded topsoil. Three years’ data shows that this soil restoration added 110-bu. yield increases in return for 216 hours’ of scraping (1,480 trips), moving 14,720 cu. yards of high-value topsoil.
“Land here in northeast Iowa sells for $150/Corn Suitability Rating (CSR) point,” Mitchell says. “So if we brought that up to an 80-CSR equivalent, we have added $12,000/acre to those areas, so the $6,000 estimate is pretty conservative.
“So the value of the land-value increase from evening out topsoil can be calculated from projecting the improvements in future cash flow, or the increased marketable value with a CSR proxy, and we conservatively get about the same value.”
His technology-enhanced erosion remediation physically moves and rebuilds topsoil depth in selected eroded areas “accomplishes in one day what would take a crew of 12 to do without telemetry (real-time data gathering),” he says. With 1 acre-inch of soil weighing 165 tons, multiple machines with automated mapping speed things considerably. Because we no-till/strip till and cover crop, this selective soil moving should last for as least several decades,” he says.
"As soil erodes from higher to lower elevations, RTK maps show where it’s moved. We can also use RTK maps to compare where we’ve scraped out grass waterways and added the soil somewhere else in a field. We look for low-productivity areas to restore, and have aerial photos extending back to the 1930s,” Mitchell says.Thanks to telemetry, each pass across a field contributes more data to a field’s elevation map. “It’s also good for identifying areas with erosion,” he says.
See the numbers
Here is information that enters into Clay Mitchell’s calculations on how restoring accumulated topsoil boosts land value:
Current Iowa land values:
- Low grade: $3271/acre
- Medium grade: $6,721
- High grade: $9,346
- Cost per acre: $810
- Yield increase per acre: 110 bu.
- Land value increase per acre: $6,000
- One acre-inch=134 cu. Yards
- Typical cost/cu. Yard=$2 translates to $270/acre-inch
- Total round trips with scraper: 1,480 trips
- Total hours operating scraper: 216 hours
- Estimated weight of soil moved: 19,800 tons
- Total area of reclaimed cultivated land: 0.6 acres
- Total area of landscape restoration: 17.8 acres
- Total volume of soil moved: 14,720 cubic yards