ATTRIBUTES OF RECONSTRUCTED PRIME FARMLAND AFTER SURFACE COAL MINING COMPARED TO PRE-MINED CONDITIONS

摘要

Important farmland consists of prime farmland, farmland of statewide importance and local importance, and unique farmland. Prime farmland has the best combination of soil chemical and physical characteristics and suitable climate for producing food, seed, fiber, forage, and oilseed with minimum inputs of fuel and plant nutrients. Further characteristics are none to very slight hazard for wind and water erosion, none to small limitation to maintain soil quality, and sustainable. Reconstruction of Prime farmland soils after surface mining for coal are set forth in federal rules and regulations. Illinois has soil reconstruction criteria for non prime farmland soils (high capability land) that are very similar to soil reconstruction for prime farmland soils. Most of the high capability land also qualifies as farmland of statewide importance. Prime farmland soils, before the current federal law, were not reconstructed as cropland. The present federal law requires that prime farmland be reconstructed to cropland with yields equal to or more than the premined soil. Reconstructed prime farmland after surface mining for coal is dominantly massive (no soil structure) whereas typically a premined soil has structure. It has higher soil bulk density that is critical or limiting for crop root growth, lower soil root zone available water capacity, slower hydraulic conductivity, and lower corn yield than the pre-mined silty loess or lacustrine soils, loamy lacustirne soils, and some loamy glacial till soils. A possible explanation of yield differences for reconstructed mined soil and premined soil is the methods and procedures used to determine their yields. The present and future soil reconstruction of prime farmland soils will need to address saturated hydraulic conductivity (Ksat), develop technology to enhance infiltration of precipitation, and movement of water within the soil profile to result in a field capacity water content of 8 to more than 12 inches. All future soil reconstruction needs to use appropriate conservation practices and shape the landscape to increase infiltration of water into the soil.