Resource Inventory Documents Trends in Land Use
With 28 years of consistently collected land-use data at its fingertips, the USDA's Natural Resources Conservation Service (NRCS) has a clear picture of how Missourians utilize the 44.6 million acres within their state's borders, and how their decisions impact natural resources. After Congress directed USDA to track land-use and erosion trends, NRCS developed the National Resources Inventory (NRI), which was expanded to its current size in 1982.
Terry Barney, Missouri's resources inventory coordinator, says 8,700 tracts of land, averaging 160 acres, are inventoried every five years, using an annual rotation of 1,800 tracts. In addition to land use, the NRI tracks erosion rates for both cropland and pastureland acres.
"Unlike many other inventories, NRI tracks the same sample points year after year. This lets us not only determine current land use but also how land use is changing over time across the state and the nation," Barney says. "Change includes knowing where all the acreage gains and losses for a particular land-use category came from and went to over the last 28 years."
In terms of land use, Barney says the large "cropland" category has seen little change in total acres over the years. It has remained steady at about 14.8 million acres. However, there have been shifts within that category. For example, after USDA unveiled its Conservation Reserve Program (CRP) in 1985, cultivated cropland acres declined while grassland acres increased. That's because CRP pays farmers to convert highly erodible land from crop production to permanent vegetation.
CRP and other conservation programs and policies included in the 1985 Farm Bill and subsequent farm bills, have had a dramatic effect on soil erosion. Because of those programs and passage of a one-tenth-cent sales tax in Missouri to fund state parks and to help farmers afford soil conservation activities, the state's soil erosion rate decreased more than any other state over a 25-year period. Missouri's sheet and rill erosion rate on cultivated cropland declined 51 percent -- from 10.8 tons per acre in 1982 to 5.2 tons per acre in 2007.
The past few years have provided an indication of how quickly trends can change, however. For example, with high grain prices coinciding with the expiration of many CRP contracts, some farmers chose to put their CRP ground back into crops instead of renewing their CRP contracts.
Barney says cultivated cropland acreage increased by 126,000 acres between 2007 and 2010, and 108,000 of those acres (65 percent) came from land that had been enrolled in CRP. During that same time period, Missouri's soil erosion rate increased from 5.2 tons per acre per year to 5.5 tons per acre per year. That represents the first increase in the state's soil erosion rate after more than 25 years of steady decline.
"CRP acres decreased, and the number of cultivated cropland acres and the soil erosion rate increased. That's probably not a coincidence," Barney says.
Barney says Missouri is one of 13 states that have maintained a cropland base of more than 10 million acres over the past 28 years. With the state's diverse topography and erosive soils, that has presented a natural resources dilemma.
"We've been maintaining a large cropland base on very erosive soils for many decades," he says.
Missouri State Conservationist J.R. Flores says working with Missouri farmers to keep soil erosion at a low enough level to maintain long-term productivity is a massive effort that requires teamwork and the sharing of resources at the local, state and federal levels.
"The conservation partnership in Missouri is the envy of many other states," Flores says. "This successful effort starts with the residents of the state, who on multiple occasions have voted to tax themselves to help farmers preserve our natural resources. And, of course, most important to this effort are the farmers who embrace their roles in being good land caretakers."
Flores says more highly erosive land being put back into crop production is a concern. But he says he is encouraged by the interests of many farmers in including cover crops in their crop rotations and farming in other ways that improve the soil's health. Healthy soils absorb more rainfall, so there is less runoff to carry soil away from fields.
Flores adds that collecting and analyzing NRI data is time-consuming, but it is important because the data is used extensively by USDA in developing and providing conservation programs.
More information about NRI and other NRCS programs is available on the Missouri NRCS website: www.mo.nrcs.usda.gov.