Lacustrine parent materials result from sediment deposited in lakes formed by glacial meltwater. Residue management becomes an important factor in maintaining high productivity. Erosion is a major concern for these soils because of the silt loam texture. Soils formed in this material are generally poorly drained and behave similarly to soils formed in glacial till. Loess in southwestern Minnesota is deposited over glacial till. Because of the porous state of the underlying materials in southeastern Minnesota, the soils are generally well-drained. Most soils formed in loess occur in southeastern Minnesota where the loess deposits are on top of limestone or sandstone. Soils formed in loess generally have silt loam textures and no rocks. These silt deposits can range in depth from a few inches to many feet. Loess is windblown, silt-sized material deposited after the glacier melted. The poor drainage has a large influence on nitrogen management and cultural practices. Soils formed in this material generally have silty clay loam to silty clay textures, many different rock sizes and poor internal drainage. As the last glacier was melting, these materials were deposited. Till is predominant in the south-central, west-central and southwestern parts of the state. Figure 1 lists five major parent materials: Till, loess, lacustrine, outwash and till over bedrock. This may seem like a long time but is considered recent in the context of soil formation and geology. The common factor among Minnesota soils is that they were formed by the last glacier in the northern United States, 11,000 to 14,000 years ago. Minnesota is a land of geologically young soils with many different parent materials (Figure 1). Figure 1: Parent materials of Minnesota soils.
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