Soil Acidification as Affected by Phosphorus Sources and Interspecific Root Interactions between Wheat and Chickpea

A pot experiment was conducted to determine the effects of chickpea/wheat intercropping and two phosphorus (P) sources on soil acidification and to explore a new way of ameliorating soil acidification. Wheat and chickpea roots were grown in compartments separated either by a solid barrier to prevent any root interactions or by a nylon mesh (30 mu m) to permit partial root interactions, or with no separation between the compartments. Two P sources were applied at 60 mg P kg(-1) soil either as sodium phytate or ferrous phosphate (FePO4). The decline of soil pH after growing plants for 42 days was alleviated by supplying organic P or intercropping while receiving organic P. The ameliorating of soil acidification resulted mainly from a decrease in excess cations over anion uptake of both wheat and chickpea under phytate supply, compared to FePO4 supply. The excess cation uptake of chickpea was reduced by root interactions.