Define the uses of buffer method
The buffer method of Shoemaker and coworkers for determining lime requirement is being widely used in India. In this method 5g of soil is added to 5ml of distilled water and 10ml of the extractant buffer (1.8g nitrophenol, 2.5ml triethanolamine, 3.0g potassium chromate, 2.0g calcium acetate, 53.2g calcium chloride dihydrate are dissolved in a litre of distilled water and the pH adjusted to 7.5 with dilute NaOH solution) and stirred continuously for ten minutes or intermittently for 20 minutes.