The essential macronutrients like nitrogen(N), phosphorus(P) and potassium(K) are optimum for plant growth. Any changes in nutrient concentrations retard the plant development, hence needs to be checked every now and then.
To check for the nutrient aspect in the soil, ‘Soil Testing ’ is done. The soil testing involves the full range of chemical, physical and biological tests that are carried out on a submitted sample of soil.
Soil tests help maintain effective and efficient nutrient management. Here are some basic soil tests facilitating nutrient checklists.
- Modified Morgan’s Extraction
- Cation Exchange Capacity (CEC)
Modified Morgan’s Extraction
Originally developed at University of Connecticut in the 1930’s, Modified Morgan Extraction procedure is a universally used extraction method of obtaining major and minor nutrients measured in single extract.
A single extraction procedure, using Morgan Universal Extraction Solution, provides the liquid soil extract for all the nutrient tests with the exception of chloride, which is extracted with demineralized water.
Cation Exchange Capacity (CEC)
Soil samples are usually drawn from the surface 0-10 cm. This is a present electrically charged surface of soil particles which captures the soil nutrients. The capacity of soil to hold major cations Ca, Mg, K, Na is known as Cation Exchange Capacity (CEC).
It helps measure the ability of soil to retain and supply nutrients. CEC is measured in terms of milli-equivalents per 100 grams of soil. Accounts >5meq/100g for sandy, 15meq/100g for low organic matter soil and high for higher organic matter soil.
Lower CEC of soil reflects more susceptibility to nutrient loss over leaching through erosion and irrigation.