Submitted to: Encyclopedia of Agrophysics
Publication Type: Popular Publication
Publication Acceptance Date: 7/1/2010
Publication Date: 7/5/2011
Citation: Busscher, W.J. 2011. Hard-pan soils - Management. In: Glinski, J., Horabik, J. Lipiec, J., editors. Encyclopedia of Agrophysics. The Netherlands: Springer. p. 357-359.
Technical Abstract: Hard pans, hard layers, or compacted horizons, either surface or subsurface, are universal problems that limit crop production. Hard layers can be caused by traffic or soil genetic properties that result in horizons with high density or cemented soil particles; these horizons have elevated penetration resistances that limit root growth and reduce water and air flow. Limited root growth leads to limited crop water and nutrient uptake. Reduced water flow prevents rainfall or irrigation water from filtering into the soil profile where it can be stored for plant growth. Reduced air flow limits oxygen and carbon dioxide exchange with the atmosphere; exchange is needed for plant and microorganism respiration. These limitations reduce crop productivity. Improving the hard layer consists of reducing its hardness or penetration resistance. When we reduce the layer’s hardness, we assume that it and/or the layers below it have properties conducive to plant growth. As the hard layer softens, water and air are able to move into and/or through it and into the layers below, improving conditions for root growth and with it productivity. There are several ways to improve hard layers; the most common is tillage; but other solutions exist in the forms of soil amendments, crop management to improve soil organic matter, and water management to soften the hard layer. Whether or not you work in agriculture, hard soil layers affect you because of their impact on food, fiber, and energy production. As populations increase and as we make more demands on our resources, we will require tillage management and other areas of agriculture to produce more food for more people with a limited and dwindling soil base. We can all become involved by being educated and active in conservation efforts to enrich our soils, our environment, and our society.