What is soil base saturation?
Base saturation is calculated as the percentage of CEC occupied by base cations. Figure 2 shows two soils with the same CEC, but the soil on the right has more base cations (in blue). Base saturation is closely related to pH; as base saturation increases, pH increases. …
Why are they called base cations?
A base cation is essentially a positively charged ion from group 1 or 2 of the periodic table (the alkali metals or alkaline earth metals). The most environmentally abundant of these are Na, K, Ca and Mg. Base cations are important in the environment because their deposition has an impact on the surface pH.
What are soil exchangeable bases?
Exchangeable bases are commonly defined as the alkali and alkaline earth metals (principally calcium, magnesium, potassium and sodium) attached to the clay and organic constituents of soils and which can be exchanged with each other and with other positively charged ions in the soil solution.
What is a good base saturation?
Base Saturation for soils to be productive must be greater than 80%. A soil that has a Base Saturation of less than 40% will develop problems and it will be difficult for this field to produce a crop.
What is CEC and AEC?
Cation exchange capacity (CEC) represents the quantity of negative charge available to attract cations. Anion exchange capacity (AEC) represents the positive charge available to attract anions in solution.
What is a good CEC in soil?
The five exchangeable cations are also shown in soil test results as percentages of CEC. The desirable ranges for them are: calcium 65–80% of CEC, magnesium 10–15%, potassium 1–5%, sodium 0–1% and aluminium 0%.
What are the two types of acidity?
Pools of Soil Acidity
- Active acidity is the quantity of hydrogen ions that are present in the soil water solution.
- The second pool, exchangeable acidity, refers to the amount of acid cations, aluminum and hydrogen, occupied on the CEC.
- Residual acidity comprises of all bound aluminum and hydrogen in soil minerals.
Which soil has highest base saturation?
In general, if the soil pH is below 7, the base saturation is less than CEC. At pH 7 or higher, soil clay mineral and organic matter surfaces are occupied by basic cations, and thus, base saturation is equal to CEC. Figure 2 illustrates the relative amount of cations retained on soil surfaces at various soil pH levels.
What is base saturation in soil chemistry?
Base Saturationis the measure of the relative quantity of the basic elements (potassium, calcium, magnesium and sodium) present on the cation exchange sites in the soil. Soils that have a pH in the neutral to basic range (6.5 – 8.0) have a higher base saturation. Hydrogen (H+) is an acidic cation and is the source of acidity in the soil.
What is the harmonized World Soil Database?
The Harmonized World Soil Database is a 30 arc-second raster database with over 15000 different soil mapping units that combines existing regional and national updates of soil information worldwide (SOTER, ESD, Soil Map of China, WISE) with the information contained within the 1:5 000 000 scale FAO-UNESCO Soil Map of the World (FAO, 1971–1981).
What is the World Reference Base for Soil Resources Classification?
The original data were updated and modified according to the World Reference Base for Soil Resources classification system. The corrections concerned boundary issues, areas with no information, soil patterns, river and drainage networks, and dynamic features such as sand dunes, water bodies and coastlines”
What is the ratio of basic cations in the soil?
Advocates of the BCSR maintain that there is an approximate ratio of basic cations that must occupy the soil CEC or plant growth will be limited. The amount of Ca 2+, Mg 2+, K + in the soil can vary considerably depending upon the given soil’s CEC and actual base saturation.