Phosphate, Fe and Mn uptake of N2 fixing red clover and ryegrass from an Oxisol as affected by P and model humic substances application. 1. Plant parameters and soil solution composition
Year: 1995
Type: article
Abstract: The effect of humic substances on P‐availability in soil is still debated. Therefore, the effect of model humic substances synthesized from hydroquinone on P, Fe, and Al solubility in a strong P fixing Oxisol and on P acquisition by red clover and ryegrass was investigated. After 4 months of incubation, P concentration of soil solution had increased by a factor of > 10 at the highest humic level (50 g humics kg−1 soil), accompanied by a similar increase in Fe and Al concentrations. Soil samples with 0, 10, 30, 50 g humics kg−1 soil were planted with red clover and ryegrass. Red clover showed a small increase of shoot yield and a moderate increase of P uptake after humics addition. High humics levels increased slightly Fe concentration in the shoots but strongly that of Mn leading to Mn toxicity. Ryegrass showed a strong increase in shoot yield after humics addition of about 150 % at the highest humics level compared to the control without humics. At each humic level, P application (100 mg kg−1 soil) had no effect on P uptake of red clover and a small effect on P uptake by ryegrass. The relatively small effect of humics and P application on shoot yield of clover compared to grass can be explained by chemical P mobilization of red clover via exudation of citrate (about 12 μmol citrate g−1 soil). This agrees with the finding that P solubility increased in the soil under red clover but not under ryegrass from the first to the second harvest, indicating that red clover mobilized P.
Authors: Jörg Gerke, Ute Meyer, Wilhelm Römer
Institution: University of Göttingen
Language: English
Subfield: Soil Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: green
OpenAlex ID: W2020930212