Interelement relations in extracts simulating mobilizable soil fractions

 Interelement relations in extracts simulating mobilizable soil fractions

Whereas many standardized soil extracts target only at a few parameters, ICP multielement determinations enable to trace interelement effects, respective correlations and possibly data simulations of amounts leached by other extractants. Ammonium salts and dilute organic acids are most favorable for the plasma torch, but salt solutions like LiCl, BaCl₂, or CAL (Ca-acetate-lactate) need specially matrix matched standards. Sr blanks in CAL and Ni blanks in LiCl have to be considered anyway.

Mobilizable amounts of nutrient and trace elements from soil and related non-polluted substrates, have been compiled from monitoring and research projects of organic farming, obtained within the last 8 years. Up to 22 elements have been measured in the extracts, but some of them may remain below detection limits. As weakest extractants, water and LiCl are only suitable to release alkali, alkaline earths, P and S. Dilute acetic and formic acid act by mobilizing more due to their acidity, whereas acid complexants like CAL, oxalate pH3 and NH₄-citrate attack pedogenic oxides in addition, and 0,5M HCl releases even more. Expectable concentration ranges versus aqua regia data will be given.

The samples will be grouped according to their carbonate, humics and nitrogen contents, in order to detect different concentration ranges and interelement effect, particularly for P and S.