One hundredth molar calcium chloride extraction procedure. part I: A review of soil chemical, analytical, and plant nutritional aspects

Abstract

The economical and operational aspects of multinutrient extractants make them attractive for soil testing programs. However, the value of a multi element extractant is primarily determined by the relationship between the amount of nutrient extracted and crop response. To determine the perspectives of the 0.01M calcium chloride (CaCl2) extraction procedure as a multinutrient extractant, this paper reviews literature on the soil chemical, analytical and plant nutritional aspects of CaCl2 solutions as a soil extractant. Recent decades, CaCl2 solutions were common single nutrient extractants in plant nutritional and soil chemical research but the amount of nutrient extracted was sensitive for differences in sample treatment and extraction procedure. Therefore, a 0.01M CaCl2 procedure should be standarized to obtain a robust procedure. Calibration studies between conventional soil extraction procedure and the 0.01M CaCl2 procedure show fairly good relationships. A first step to develop a multielement 0.01M CaCl2 soil testing program is to convert conventional soil testing programs into 0.01M CaCl2 programs based on these relationships. Validation of these programs with pot and field experiments remains necessary. Further research is suggested to test if the ‘labile’ pool of plant nutrients in a soil can be estimated based on the pH. The composition of the supernatant and soil characteristics. It is concluded that the 0.01M CaCl2 procedure is a promising tool in near future farm nutrient management.