Phosphorus released by pigeonpea
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CTA. 1992. Phosphorus released by pigeonpea. Spore 39. CTA, Wageningen, The Netherlands.
Permanent link to this item: http://hdl.handle.net/10568/45759
Pigeonpea can release and use soil phosphorus that is unavailable to other crops. Crops that follow pigeonpea benefit not only from residual nitrogen, but from extra phosphorus as well. Scientists at the International Crops Research Institute for...
Pigeonpea can release and use soil phosphorus that is unavailable to other crops. Crops that follow pigeonpea benefit not only from residual nitrogen, but from extra phosphorus as well. Scientists at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in India, were intrigued when they noticed that pigeonpea did not respond to applications of phosphorus, especially when it was applied to soils that were known to be deficient, even though other crops did respond. Studies revealed that pigeonpea was not getting the extra phosphorus via mycorrhizal fungi. Further research showed that the roots of pigeonpea were exuding piscidic acid, which was found to be responsible for the release of phosphorus bound up with iron. Phosphorus is very often tied up in this way, making it unavailable to most plants. Chickpea, especially when it is grown on calcareous soils, exudes malic acid which releases phosphorus tied up with calcium. Normally phosphorus in calcareous soils would only be released if the pH was lowered. Through leaf fall and plant residues both cross will increase phosphorus levels in the soil, so benefiting the crops that follow. It means too that nutrients are being brought up from lower levels in the soil because pigeonpea and chickpea are more deeply rooted than some of the other crops. Further studies will show if varieties of both crops vary in the amount of acid that they exude. If they do, then this will be another trait to select for in plant breeding. ICRISAT, Patancheru PO Andhra Pradesh 502 324 INDIA