Soil Cation Exchange Capacity
The Cation Exchange Capacity (CEC) in laymen's terms is basically a rating of the soil's ability to hold nutrients or a fertility-holding capacity. The CEC number represents milliequivalents (ME) and can be thought of as a storage battery holding volts of electricity. The higher the number, the more storage capacity or milliequivalents the soil can hold.
High CEC soils hold nutrients longer, prevent leaching, maintain high microbial activity and help hold moisture in the root zone area. The only practical way to increase the CEC rating of a soil would be to increase humus levels. This can be achieved by adding organic matter such as compost, returning harvest residues, growing permanent cover crops or applying carbon based fertilizers. Fertile soils should have an organic content of 2 to 5 percent.
It should be noted that most fertilizer chemicals can rapidly destroy soil humus. Examples are sulfuric acid, anhydrous ammonia, and salt-based fertilizers. Many pesticides may effect the same destruction. To offset the negative effects of applications of these products, a grower should also apply a good, high carbon soil amendment such as BioFlora HUMEGA with every application. This will help maintain a higher CEC rating essential for developing a fertile soil.
In chemistry the cation exchange elements or molecules are called either cations or anions. A cation is a positive charge (+) element and an anion is a negative (-) charge molecule. Opposite charges (+ and -) attract each other while similar charges repel each other. Plants and soils have an anion or negative charge (-) and thus attract, hold and exchange nutrients with cation elements that have a positive charge (+). Some of the important cation or positive charge (+) nutrients are listed as follows:
Calcium: Ca++ Magnesium: Mg++
Potassium: K+ Manganese: Mn++
Hydrogen: H+ Sodium: Na+
Copper: Cu++ Zinc: Zn++
Ammonium: NH4+
Soil particles (sand, silt, clay or humus) have a negative charge and the CEC numbers can vary considerably from one soil type to another. The CEC ratings of various soil types are as follows:
Sand: 0 to 2 CEC
Silt: 2 to 5 CEC
Clay: 30 to 45 CEC
Humin: 100 to 300 CEC
Humic Acid: 300 to 500 CEC
Fulvic Acid: 500 to 1,000 CEC
High CEC soils hold nutrients longer, prevent leaching, maintain high microbial activity and help hold moisture in the root zone area. The only practical way to increase the CEC rating of a soil would be to increase humus levels. This can be achieved by adding organic matter such as compost, returning harvest residues, growing permanent cover crops or applying carbon based fertilizers. Fertile soils should have an organic content of 2 to 5 percent.
It should be noted that most fertilizer chemicals can rapidly destroy soil humus. Examples are sulfuric acid, anhydrous ammonia, and salt-based fertilizers. Many pesticides may effect the same destruction. To offset the negative effects of applications of these products, a grower should also apply a good, high carbon soil amendment such as BioFlora HUMEGA with every application. This will help maintain a higher CEC rating essential for developing a fertile soil.
In chemistry the cation exchange elements or molecules are called either cations or anions. A cation is a positive charge (+) element and an anion is a negative (-) charge molecule. Opposite charges (+ and -) attract each other while similar charges repel each other. Plants and soils have an anion or negative charge (-) and thus attract, hold and exchange nutrients with cation elements that have a positive charge (+). Some of the important cation or positive charge (+) nutrients are listed as follows:
Calcium: Ca++ Magnesium: Mg++
Potassium: K+ Manganese: Mn++
Hydrogen: H+ Sodium: Na+
Copper: Cu++ Zinc: Zn++
Ammonium: NH4+
Soil particles (sand, silt, clay or humus) have a negative charge and the CEC numbers can vary considerably from one soil type to another. The CEC ratings of various soil types are as follows:
Sand: 0 to 2 CEC
Silt: 2 to 5 CEC
Clay: 30 to 45 CEC
Humin: 100 to 300 CEC
Humic Acid: 300 to 500 CEC
Fulvic Acid: 500 to 1,000 CEC