Cowpea N rhizodeposition and its below-ground transfer to a co-existing and to a subsequent millet crop on a sandy soil of the Sudano-Sahelian eco-zone

Laberge, G and Haussmann, B I G and Ambus, Per and Hogh-Jensen, H (2011) Cowpea N rhizodeposition and its below-ground transfer to a co-existing and to a subsequent millet crop on a sandy soil of the Sudano-Sahelian eco-zone. Plant and Soil, 340 (1-2). pp. 369-382. ISSN 0032-079X

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Abstract

Nitrogen (N) rhizodeposition by cowpea (Vigna unguiculata (L.) Walp) is potentially a large N source in cropping systems of Sub-Saharan Africa. A field experiment was conducted to measure cowpea N rhizodeposition under the conditions of the Sudano-Sahelian zone using direct 15N labelling techniques to trace the amount of deposition and its transfer to associated and subsequent crops. Half of the total cowpea crop N was located below-ground at plant maturity, which exceeded 20 kg N ha−1 when intercropped with millet. Only 15% of the below-ground cowpea N was recovered in roots, while 85% was found in the rhizodeposited pools. The experiment demonstrated that direct below-ground N transfer occurred from cowpea to millet in intercrop at a rate of 2 kg N ha−1 over the growing season. Forty percent of the 25 kg below-ground N that the cowpea crop left at harvest were identifiable in the top 0.30 m soil in the beginning of the next planting season 7 months later; a pool still present at the end of that second season. Thus, the subsequent crop of millet (Pennisetum glaucum (L.) R. Br.) only recovered 2.5 kg N ha−1 from the below-ground cowpea pre-crop N during this growth season. The role and potential of cowpea as N provider has been underestimated in the past by ignoring the large proportion of N contained in its rhizodeposits. However, information is needed to determine how losses of the rhizodeposited N can be minimized to fully harness the potential of cowpea as N provider in agro-ecosystems of the region.

Item Type: Article
Divisions: UNSPECIFIED
CRP: UNSPECIFIED
Subjects: Mandate crops > Millets
Depositing User: Users 6 not found.
Date Deposited: 08 Nov 2011 04:03
Last Modified: 14 Sep 2013 12:16
URI: http://oar.icrisat.org/id/eprint/3787
Official URL: http://dx.doi.org/10.1007/s11104-010-0609-6
Projects: UNSPECIFIED
Funders: UNSPECIFIED
Acknowledgement: The authors wish to thank Tahirou Saley and Amadou Mounkeila along with Chindo, Tindi and Issaka Kouarokoye for their skilled technical assistance. The contributions of Dr. Matsunaga and the JIRCAS program at ICRISAT who provided the cowpea seeds and the millet breeding program of ICRISAT who provided the millet seeds should also be acknowledged.
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