| A | B |
|---|
| available water capacity | an estimate of how much water a soil can hold and release for use by plants |
| field capacity | the amount of water that soil can hold after the gravitational water has drained away |
| gravitational water | the water that moves into, through, and out of soil by gravity |
| wilting point | the amount of water held by a soil that is beyond the ability of most plants to extract |
| reaction (soil pH) | the measure of alkalinity and acidity of a soil |
| acidity of a soil | determined by the amount of hydrogen ions outnumber the number of hydroxyl ions in the soil |
| alkalinity of a soil | determined by the amount of hydrogen ions outnumber the hydroxyl ions in soil |
| alkaline | basic |
| most NC soils | pH 4.5 to 6.0 (acidic) |
| western NC, drier soils | area of NC that tend to have higher pH soil level |
| above pH 8.5 | too alkaline for plants |
| below 3.5 pH | too acidic |
| lime (ground limestone) | used to raise the pH of soil |
| acid deposition | any kind of cloud vapor or precipitation with a low pH and the deposit of dry acidic particles |
| severity of acid deposition | depends on the soil pH |
| cation-Exchange Capacity (CEC) | the measure of the ability of a soil to hold and exchange cations |
| cations | positively charged ions |
| ion | An atom or a group of atoms that has acquired a net electric charge by gaining or losing one or more electrons. |
| one of the most important chemical properties in soil | Cation-Exchange Capacity |
| some plant nutrient cations | calcium, magnesium, potassium, iron, and ammonium |
| clay particles | have a negatively charged surface |
| Soil Taxonomy | the official book used for classifying soils |
| soil series | a named soil (20,000 different USA kinds) |
| ultisols1 | dominant soil order in NC |
| ultisols2 | low amount of plant nutrients and clay increase in B horizon; often highly weathered |
| soil survey | a systematic examination, description, classification and mapping of soils in an area |
| land capability class | assigned to each soil suggesting suitability of the soil for field crops or pasture |
| Class I (land capability) | few limitations |
| Class II (land capability) | some limitation that reduce choice of plants or require moderate conservation practices |
| Class III (land capability) | severe limitations |
| Class IV | very severe limitations |
| Class V | not suited for cultivation |
| Class VI | unsuited to cultivate; limited to pasture |
| Class VII | use restricted to grazing, wildlife or woodland |
| Class VIII | use restricted to recreation, water supply, wildlife or aesthetics |
| Subclass "e" | indicates soil is erosive |
| Subclass "w" | indicates a wetland limitation (it is wet often) |
| Subclass "s" | indicates shallow, droughty, or stony soil |
| Subclass "c" | indicates a climatic limitation |
| hydric soils | develop under wet conditions; anaerobic within 12 inches; hydrophytic vegetation |
