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Soil Health-Bulk Density and Texture—Elbert County,Colorado,Western Part <br /> Soil Health - Bulk Density and Texture <br /> Bulk density is a physical soil property measured by the ratio of dry weight of soil <br /> to its volume. <br /> Significance <br /> Bulk density is one of several soil properties frequently used as a measure of soil <br /> health (Volchko, et al., 2014)and is an indicator for soil compaction and root <br /> restriction. Even though bulk density varies with soil texture, it is a dynamic soil <br /> property that changes based on soil management with different soil cover, <br /> amount of organic matter, soil structure, and porosity (USDA, 2008). It influences <br /> water movement in the soil,root growth and penetration and seed germination. <br /> Some of the practices that can improve bulk density include increasing organic <br /> matter content, reducing soil disturbance when the soil is wet, and maintaining <br /> soil surface protection with a cover crop, especially multi-species that can <br /> provide a wide range of root penetration. <br /> Bulk density influences plant growth and engineering applications. Within a family <br /> level particle-size class, bulk density is an indicator of how well plant roots are <br /> able to extend into the soil. Bulk density is used to calculate porosity. Bulk <br /> density at a water tension of 1/3 bar(33 kPa)is used for soil classification in the <br /> required characteristics for andic soil properties and in the criteria for Andic, <br /> Aquandic, and Vitrandic subgroups. <br /> Factors Affecting Bulk Density <br /> Inherent-Bulk density is dependent on soil texture and the densities of soil <br /> mineral(sand, silt, and clay)and organic matter particles, as well as their packing <br /> arrangement. Generally, loose, porous soils and those rich in organic matter <br /> have lower bulk density. Sandy soils have relatively high bulk density since total <br /> pore space in sands is less than that of silt or clay soils. Finer-textured soils that <br /> have good structure, such as silt loams and clay loams, have higher pore space <br /> and lower bulk density compared to sandy soils. <br /> General relationship of soil bulk density to root growth based on soil <br /> texture <br /> Soil Texture Ideal bulk denafts for plant growth(gf Bulk densities fiat restrict root growth <br /> cm3) (91=3) <br /> Sandy Less than 1.60 More than 1.80 <br /> Loamy Less than 1.40 More than 1.65 <br /> Clayey Less than 1.10 More than 1.47 <br /> Dynamic-Bulk density is changed by crop and land management practices that <br /> affect soil cover, organic matter, soil structure, and/or porosity. Cultivation can <br /> result in compacted soil layers with increased bulk density. Livestock as well as <br /> the use of agricultural and construction equipment exert pressure that compacts <br /> the soil and reduces porosity, especially on wet soils. Freeze-thaw action in the <br /> soil can lead to lowered bulk density. <br /> Database Entries <br /> l Natural Resources Web Soil Survey 3/12/2018 <br /> Conservation Service National Cooperative Soil Survey Page 1 of 4 <br />