Wasserlösliche Zucker und Carbonsäuren in der Rhizosphäre von Erbsen, Zuckerrüben und Sommergerste unter Feldbedingungen

Abstract

Water-soluble organic compounds were determined in the rhizosphere of spring barley (Hordeum vulgare), pea (Pisum sativum) and sugar beet (Beta vulgaris) growing in a long-term fertilization trial with varied lime and phosphorus fertilization. The identified substances include root exudates, their microbial metabolites and products of microbial decomposition of roots, plant and humus residues. Under field conditions, a remarkable accumulation of potentially nutrient mobilizing carboxylic acids and lower amounts of neutral substances were found in comparison to isotope labelled root exudates in pot experiments. The composition of water-soluble substances was highly affected by plant species, whereas fertilization effects were not significant.

A plant influence on soil pH and phosphorus dynamics was detectable in October after the harvest of all crops (acidification by pea and sugar beet; increased P availability after pea; reduced double-lactate soluble P contents, but increased P release after repeated water extraction after sugar beet).