Premium
Plant Effects on Soil Manganese Availability
Author(s) -
Godo Gnahoua H.,
Reisenauer H. M.
Publication year - 1980
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1980.03615995004400050024x
Subject(s) - rhizosphere , exudate , bulk soil , solubility , chemistry , manganese , soil water , soil ph , nutrient , environmental chemistry , divalent , agronomy , soil science , soil fertility , botany , environmental science , geology , biology , bacteria , paleontology , organic chemistry
Relationships differ greatly between soil Mn solubility and pH, between plant uptake of Mn and soil pH, and between plant uptake of Mn and nutrient solution pH. The discrepancies suggest that soil Mn availability is controlled by neither soil nor plant characteristics per se but by the combined effects of soil properties, plant characteristics, and the interactions of plant roots and the surrounding soil. Experiments were done to evaluate the contributions of root/soil interactions, specifically those of root exudates, to Mn availability. The solubility of soil Mn and of MnO 2 in root exudates and in rhizosphere and bulk soils was measured over the pH range of 4.5 to 6.5. The relationships between pH and MnO 2 solubility in solutions of root exudates and selected root exudate components closely resembled those between plant uptake of Mn and soil pH. Similarly, the relationship between CaCl 2 ‐soluble Mn in the rhizosphere soil and soil pH resembled that between plant uptake of Mn and soil pH. The pattern with pH of the CaCl 2 ‐soluble Mn of the bulk soil was that of soil alone and fell below that of the rhizosphere soil. These relations establish that root exudates make an important contribution to plant uptake of soil Mn. Exudate compounds, such as hydroxy‐carboxylates, increase soil Mn solubility through reducing MnO 2 and complexing the divalent Mn released. The effect is particularly marked in systems more acid than pH 5.5 and explains many of the apparent anomalies of soil Mn availability.