| A | B |
|---|
| predominantly sandy soils | very porous, not good for agriculture (cannot retain water/nutrients), and prone to erosion |
| predominantly silty soils | favorable for agriculture (water-holding capacity); building problems: will shift under stress |
| predominantly clay soils | retain water very well but too sticky to work with when wet |
| total amount of pore space | highest in clay soils |
| important reservoir of plant food | clay soils1 |
| (1) large surface area and (2) negative electrical charge | clay soils2 |
| excess nutrients runoff into aquatic ecosystems, resulting in over-growth of algae/plants | eutrophication |
| cultural eutrophication | actions of man (ie, fertilizers) causes overgrowth of plant growth in water systems |
| most productive soil textures for agriculture | sandy loam, loam, and silt loam |
| soil texture triangle | show the percentages of sand, silt, and clay |
| soil structure | the arrangement of soil particles |
| granular soil structure | small (less than 1/4 inch), rounded aggregates; lie loosely on surface (topsoil) |
| single grain soil structure | each particle is separate and there is essentially no structure (beach) |
| blocky soil structure | cube-shaped aggregates |
| aggregate | A total considered with reference to its constituent parts |
| subangular blocky soil structure | rounded edges and corners of a cube-shaped aggregate (NC B horizon) |
| angular blocky soil structure | sharp edges and distinct rectangular face on cube-shaped aggregate |
| prismatic soil structure | vertical oriented aggregates with flat tops (high clay content) |
| columnar soil structure | vertical oriented aggregates with rounded tops (high salt content soils) |
| platy soil structure | arranged in thin, horizontal layers of plates or sheets (compacted soils) |
| massive soil structure | complete absence of structure (parent material) |
| soil consistence | cohesion and/or the resistance to deformity the soil holds under stress |
| rupture resistance | measure of the soil's ability to withstand applied stress |
| stickiness | the capacity of a soil to adhere to other objects |
| plasticity | the degree to which a "rolled" soil can support itself when held on one end |
| shrink-swell potential | measurement of the amount of volume change that can occur when a soil wets and dries |
