What is CEC soil?
Cation exchange capacity (CEC) is a useful indicator of soil fertility because it shows the soil’s ability to supply three important plant nutrients: calcium, magnesium and potassium.
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.
How do you find the CEC of soil?
To determine the cation exchange capacity (CEC), calculate the milliequivalents of H, K, Mg, and Ca per 100g of soil (meq/100g soil) by using the following formulas: H, meq/100g soil = 8 (8.00 – buffer pH) K, meq/100g soil = lbs/acre extracted K ÷ 782. Mg, meq/100g soil = lbs/acre extracted Mg ÷ 240.
What is the base saturation of fertile soil?
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). Therefore, it has a higher base saturation. Base saturation is closely related to pH; as base saturation increases, pH increases.
Which soil has the highest CEC?
Humus
Humus, the end product of decomposed organic matter, has the highest CEC value because organic matter colloids have large quantities of negative charges. Humus has a CEC two to five times greater than montmorillonite clay and up to 30 times greater than kaolinite clay, so is very important in improving soil fertility.
What does high CEC mean?
The higher the CEC, the higher the negative charge and the more cations that can be held. CEC is measured in millequivalents per 100 grams of soil (meq/100g). A meq is the number of ions which total a specific quantity of electrical charges.
What is pH level of soil?
Soils can be classified according to their pH value: 6.5 to 7.5—neutral. over 7.5—alkaline. less than 6.5—acidic, and soils with pH less than 5.5 are considered strongly acidic.
Why base saturation is significance in soil?
Soils with high percent base saturation have a higher pH; therefore, they are more buffered against acid cations from plant roots and soil processes that acidify the soil (nitrification, acid rain, etc.). They contain greater amounts of the essential plant nutrient cations K+, Ca2+ and Mg2+ for use by plants.
How does CEC affect soil fertility?
As CEC measures a soils ability to hold nutrients it is a key determinant of soil fertility. Soils with high CEC have the ability to hold more cations making them sufficient in calcium, magnesium and other cations. On the contrary, soils with low CEC are easily deficient in cations.
How many grams of calcium will replace 4 me of K+?
You need 2* 111 or 222 grams of CaCl2 to supply 4 moles of charge to replace the potassium. 4. 12 molc of K+.
What type of CEC does sand and clay have?
The CEC of soils varies according to clay content, the type of clay present, soil pH and organic matter content. Pure sand has a very low CEC, less than 2 meq/100 g. Clays such as kaolinite have a CEC of about 10 meq/100 g, while illite and smectite have CECs ranging from 25 to 100 meq/100 g.
What are the factors that affects the CEC of the soil?
Factors influencing the CEC include the soil type, the soil pH and the soil organic matter content. Soils are made up of sand, organic matter, silt and clay particles. Soils with high sand content have low holding capacity for cations compared to clayey and silty soils.
Is the BCSR analysis supported by soil scientists?
As in the UK, BCSR analysis is not generally supported by the established soil scientists in the USA. Most of the criticism stems from the emphasis put on cation ratios i.e. the ratio between calcium, potassium and magnesium. See this critique from the Sustainable Agriculture Research Association.
What are the cations in the BCSR method?
To understand the theory behind the BCSR method or specifically, the Ca:Mg ratio, one must understand cation exchange capacity (CEC). Cations are positively charged ions in the soil solution (Ca 2+, NH 4+, Mg 2+, K +, Na +, etc.).
Is there such a thing as an ideal BCSR?
The theory of an “ideal” BCSR in the soil has been extensively discussed and used to a limited extent throughout the Midwest by some soil testing labs to guide fertility recommendations.
Which is the best method for soil analysis?
Alternative methods of soil analysis and associated management strategies have been developed over the years and one of those quite widely used in the USA is the Base Cation Saturation Ratio (BCSR) analysis. The BCSR method was developed by William Albrecht at Missouri University in the 1930s.