Cation Exchange capacity

Cation exchange capacity (CEC) in soils is a measure of the soil’s ability to retain essential nutrients, reflecting the total sum of cations that can be absorbed at a given pH. High CEC levels indicate that soil can hold a larger quantity of positively charged ions, which are critical for plant growth.

In agriculture, CEC is a crucial indicator of both soil fertility and structural stability. Soils with high CEC values can support higher nutrient levels, which are essential for healthy crop production, and they can also contribute to soil structural integrity, promoting the formation of shrinkage cracks that improve aeration and water movement. CEC values, however, can vary widely depending on soil composition. For instance, quartz sand has a CEC range of 0.01-0.02 meq/g, while sedimentary clays exhibit a much broader range of 0.6-2.21 meq/g. Similarly, different minerals contribute distinctively to CEC: montmorillonite clays, for example, can achieve CEC values as high as 1 meq/g, significantly more than kaolinite, which ranges from 0.03-0.15 meq/g. This variation underscores the importance of accurately mapping CEC across agricultural fields, as these differences influence the effectiveness of nutrient management and crop growth potential.

The concentrations of radionuclides correlate with mineral composition and as such, gamma-ray spectrometry offers an effective, non-invasive method to indirectly map CEC