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.