Cation Exchange, pH and Base Saturation - 04 - 04 - - Newsletter - Novavine
Cation exchange capacity (CEC) is a measure of the soil's ability to retain and A soil with a pH between and will typically have a base saturation of After reading this article you will learn about the relationship between percentage base saturation of soil and its ph. The determination of soil pH is comparatively. Understanding CEC, Buffer soil pH, Percent Saturation unique among the negatively charged anions, in that they are not mobile in the soil. . Base Saturation.
In acidic soils with low pH, adding lime is a quick and easy way to adjust pH upward. Basic, or high pH, soils are a little more difficult to adjust.Base Saturation
Adding elemental sulfur is another means of lowering pH in soils. The next soil component to evaluate is cation exchange capacity, or CEC. There are only a few components that give soil a negative charge; the two most common are clay and organic matter. Elements such as calcium, potassium, magnesium, and others are cations and have positive charge. CEC levels will give a grower a good idea of the overall nutrient capacity as well as soil texture.
High CEC, in the range of 25 and above, represent clay dominated or fine soils. Soils with a CEC of 10 or less are sandy or course in nature.
This can have great ramifications on farming practices such as fertilization and irrigation. Fine, or clay soils retain nutrients better than sandy soils.
Course, or sandy soils have little charge and are worse at holding large quantities of nutrients. Fine soils can be fertilized less often, where course soils should be fertilized in small, but frequent doses.
Understanding CEC, Buffer soil pH, Percent Saturation
Fine soils hold a great deal more water than course soils. Therefore fine soils can be irrigated less frequently than course soil and are more prone to becoming waterlogged. CEC is very difficult to alter, but by utilizing certain tools one can work around most of the problems encountered. As an example, an effective tool for high CEC is to add gypsum to create better porosity, thereby creating better drainage.
Another mitigating technique can be to add drain tile to alleviate water logged soils. In sandy, low CEC soils, the annual addition of organic matter in the form of manures, composts and compost teas helps build better charge, better water retention and increases microbial numbers in the soil.
- Cation Exchange Capacity and Base Saturation
- Cation Exchange, pH and Base Saturation
- Percentage Base Saturation of Soil and Its pH | Soil Colloids
Base saturation is the final item to focus on as it also has ties to CEC. The importance of base saturations cannot be overstated. In general, the term refers to the level of permeation of soil surfaces by five cations, calcium Camagnesium Mgpotassium Khydrogen H and sodium Na.
Each of the cations will be represented as a percentage on the soil test. For example if a soil has a pH of 6. If the pH is lowered further to pH 4. The logarithmic nature of the pH scale means that small changes in a soil pH can have large effects on nutrient availability and plant growth.
Buffer pH BpH This is a value that is generated in the laboratory, it is not an existing feature of the soil. Laboratories perform this test in order to develop lime recommendations, and it actually has no other practical value. In basic terms, the BpH is the resulting sample pH after the laboratory has added a liming material. In this test, the laboratory adds a chemical mixture called a buffering solution.
This solution functions like extremely fast-acting lime. Each soil sample receives the same amount of buffering solution; therefore the resulting pH is different for each sample.
To determine a lime recommendation, the laboratory looks at the difference between the original soil pH and the ending pH after the buffering solution has reacted with the soil. If the difference between the two pH measurements is large, it means that the soil pH is easily changed, and a low rate of lime will suffice.
If the soil pH changes only a little after the buffering solution has reacted, it means that the soil pH is difficult to change and a larger lime addition is needed to reach the desired pH for the crop. The reasons that a soil may require differing amounts of lime to change the soil pH relates to the soil CEC and the "reserve" acidity that is contained by the soil.