Measurement of N2-fixation in field-grown pigeonpea [Cajanus cajan (L.) Millsp.] using15N-labelled fertilizer

Rao, J V D K K and Thompson, J A and Sastry, P V S S and Giller, K E and Day, J M (1987) Measurement of N2-fixation in field-grown pigeonpea [Cajanus cajan (L.) Millsp.] using15N-labelled fertilizer. Plant and Soil, 101 (1). pp. 107-113. ISSN 0032-079X

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Two experiments were carried out from 1981 to 1983 in Vertisol field at ICRISAT Center, Patancheru, India to measure N2-fixation of pigeonpea [Cajanus cajan (L.) Millsp.] using the15N isotope dilution technique. One experiment examined the effect of control of a nodule-eating insect on fixation while another in vestigated the effect of intercroping with cereals on fixation and the residual effect of pigeonpea on a succeeding cereal crop. Although both experiments indicated that at least 88% of the N in pigeonpea was fixed from the atmosphere, one result is considered fortuitous in view of the differential rates of growth of the legume and the control, sorghum [Sorghum bicolor (L.) Moench]. The difference method of calculation in dieated negative fixation and the results emphasized the problem of finding a suitable nonfixing control. In a second experiment, when all plants were confined to a known volume of soil to which15N fertilizer was added in the field, these problems were overcome, and isotope dilution and difference methods gave similar results of N2-fixation of about 90%. In intercropped pigeonpea 96% of the total N was derived from the atmosphere. This estimate might be an artifact. There was no evidence of benefit from N fixed by pigeonpea to intercropped sorghum plants. Plant tissue15N enrichments of cereal crops grown after pigeonpea indicated that the cereal derived some N fixed by the previous pigeonpea. Thus residual benefits to cereals are not only an effect of ‘sparing’ of soil N.

Item Type: Article
Uncontrolled Keywords: 15N, Cajanus cajan, intercropping, isotope dilution, nitrogen fixation, nitrogen transfer, residual effect
Subjects: Mandate crops > Pigeonpea
Others > Fertilizer Applications
Depositing User: Mr Charan Sai Ch
Date Deposited: 03 Nov 2011 03:37
Last Modified: 25 Apr 2014 03:59
Official URL:
Acknowledgement: UNSPECIFIED
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