Measurement of the effects of pH on phosphate availability

Aims Many soil scientists think that soil phosphate availability is highest at near-neutral pH and decreases with decreasing pH. This belief does not appear to have ever been subjected to experimental test. Methods In a pot trial, we measured response curves to phosphate at seven pH (CaCl2) values r...

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Bibliographic Details
Published in:Plant and soil 2020-09, Vol.454 (1-2), p.217-224
Main Authors: Barrow, N.J., Debnath, Abhijit, Sen, Arup
Format: Article
Language:English
Subjects:
Analysis
Biomedical and Life Sciences
Ecology
Life Sciences
Measurement
Phosphates
Plant Physiology
Plant Sciences
Soil Science & Conservation
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Summary:Aims Many soil scientists think that soil phosphate availability is highest at near-neutral pH and decreases with decreasing pH. This belief does not appear to have ever been subjected to experimental test. Methods In a pot trial, we measured response curves to phosphate at seven pH (CaCl2) values ranging from 3.99 to 7.26 using three plant species: mustard ( Brassica campestris ), lucerne – also known as alfalfa – ( Medicago sativa ) and rice ( Oryza sativa ). We used a form of the Mitscherlich equation that allowed us to estimate the phosphate contribution from the soil as well as the slope of the response curve and the maximum yield. Results Plants grew best near pH 5.5 and worst at near-neutral pH. We think the large decrease in growth with increasing pH was caused by decreasing rate of P uptake by plants. There was a smaller decrease in growth as pH decreased below 5.5. We think this was caused by aluminium toxicity. Conclusions The conventional belief that phosphate availability is greatest near neutral pH is wrong.
ISSN:0032-079X
1573-5036
DOI:10.1007/s11104-020-04647-5