Calcium Acetate Lactate Extract
The calcium acetate-lactate extract (short CAL-extract ) is a method for extraction of plant available phosphorus and potassium from soil samples . The concentration of these plant nutrients can then be determined in the extract .
The process was presented in 1969 by H. Schüller. The method can be used for soils with a natural carbonate content of up to 15% and for horticultural substrates.
A solution of calcium lactate , calcium acetate , acetic acid and water , buffered to pH 3.7 to 4.1 , is used as the extraction agent. In preparation, the floors are air-dried and sieved. Then they are mixed with the extractant and mechanically shaken for 90 minutes. Then the solution is filtered off and phosphorus and potassium are measured in the filtrate. A suitable measuring method is photometry , for phosphorus spectrophotometric measurement of the deep blue antimony-phosphorus molybdate complex and for potassium by means of atomic absorption spectroscopy (AAS for short) or atomic emission spectroscopy (AES for short).
The results, together with the factors soil type and management objective (grain cultivation, vegetables, grassland, etc.) serve to make a fertilizer recommendation adapted to the location .
literature
- Data sheet VDLUFA I, P and K, CAL – soluble, A 6.2.1.1 , In: Handbook of soil investigation : Terminology, procedural regulations and data sheets; physical, chemical, biological examination procedures: legal regulations. Edited by DIN, German Institute for Standardization e. V., Beuth Verlag , 2000, ISBN 3-410-14590-7
- Scheffer / Schachtschabel Textbook of Soil Science , 15th edition, Spektrum Akademischer Verlag , 2002, ISBN 3-8274-1324-9
Individual evidence
- ↑ H. Schüller (1969): The CAL method, a new method for determining the phosphate available to plants in soils. Z. Plant Nutrition., Bodenkde. 123 , 48-63