|Despite the lure of record high grain prices, farmers in 40 of Iowa’s counties developed new wildlife habitat with more land being converted to grassy habitat from cropland than grassy habitat conversions to corn and soybeans, according to a new study conducted by Decision Innovation Services.
This surprising result was one of several insights into land use change that was revealed by a new Multi-State Land Use Study conducted on behalf of seven state Farm Bureaus in the Midwest, according to Spencer Parkinson, lead researcher on the study. Another 18 Iowa counties had minimal net loss of grassy habitat (less than 10,000 acres per county) as farmers returned some expiring CRP lands to production, but converted other corn and soybean land to grassy habitat.
The Multi-State Land Use Study examined two USDA databases which report on land use. According to the USDA Crop Reporting database which relies on on-farm visits, land-use grid surveys and farmer surveys, Iowa had a net conversion of 3,500 acres of grassy habitat to cropland from 2007 through 2012. Acres planted to corn in Iowa were the same in 2012 as in 2007, soybeans gained 800,000 acres, but alfalfa acres declined by 440,000 acres and oat acres declined by 80,000 acres, highlighting that much of the shift in land use is among crops, rather than a shift in land use.
The second USDA database examined in the study was the Crop Data Layer (CDL). This database uses satellite imagery to classify cropping and land use. This data set which classifies land into more than 180 different uses was aggregated into 9 categories for the Multi-State Study.
According to this dataset, Iowa had a net loss of 1.8 million acres of grassy habitat from 2007-2012 with 1.18 million acres being converted to the primary crops covered by USDA programs. This same dataset, however, shows Iowa soybean acres increasing by more than a million acres from 2007-2012. "One of the observations from doing this study is that we gained substantial insight into the validity, or lack of validity, that can result from using only the CDL to assess land use change over time," says David Miller, director of research and commodity services for the Iowa Farm Bureau. "It appears that the land use classification accuracy of the CDL is much better now than it has been in the past." In 2007, the CDL appears to have had problems differentiating between hay ground, alfalfa and other crops that could show up as grassy habitat.
Using the CDL dataset, the study aimed to capture an accurate snapshot of how Midwestern land use is changing with the times, not only in the aggregate, but also on individual land parcels. Decision Innovations combed through about 180 different classification options with land use classified at the resolution of 30 meter by 30 meter land plots. “We then grouped these habitat types into nine different types of ground use, including corn, soybeans, wheat, other oilseeds, other agricultural use, grassy habitat, woody habitat, and non-ag lands. When we looked at this pixelated data, we saw 1.1 million acres of grassy habitat converted to corn production and 740,000 acres of grassy habitat converted to soybean production, but we also observed land use changes going the opposite way as Iowa farmers converted 414,000 corn acres into grassy habitat and 187,000 acres of soybean ground into habitat areas,” Parkinson said.
"Some reports on habitat loss have only looked at conversion of habitat to cropland. This study highlights the two-way movement of land use, conversions of cropland into grassy habitat as well as the conversion of habitat to cropland," says Miller. "In Iowa, farmers all across the state are doing the right things to improve their farms, even when that involves taking land out of corn and soybean production to put in grassy waterways, buffer strips and other grassy habitats."
Are there Iowa counties where significant habitat has occurred? "Yes," says Miller. "There are a dozen or so counties, mostly in southern Iowa, where the whole-farm CRP enrollments are expiring and some of that land is being brought back into production using no-till and other conservation minded techniques. But, we found no conclusive evidence that crop insurance subsidies are a driving factor in conversion from habitat in Iowa."