15N studies on the transfer of legume-fixed nitrogen to associated cereals in intercropping systems |
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Authors: | D D Patra M S Sachdev B V Subbiah |
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Institution: | (1) Nuclear Research Laboratory, Indian Agricultural Research Institute, 110012 New Delhi, India;(2) Present address: Department of Soil Science and Agricultural Chemistry, SKN College of Agriculture, Jobner, 308329 Rajasthan, India |
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Abstract: | Summary An attempt has been made to estimate quantitatively the amount of N fixed by legume and transferred to the cereal in association in intercropping systems of wheat (Triticum aestivum L.) — gram (Cicer arietinum L.) and maize (Zea mays L.) —cowpea (Vigna unguiculate L.) by labelling soil and fertilizer nitrogen with 15N. The intercropped legumes have been found to fix significantly higher amounts of N as compared with legumes in sole cropping if the intercropped cereal-legume received the same dose of fertilizer N as the sole cereal crop. But when half of the dose of the fertilizer N applied to sole cereal crop was received by intercropped plants, the amount of N fixed by legumes in association with cereals was significantly less than that fixed by sole legumes. Under field conditions 28% of the total N uptake by maize (21.2 kg N ha–1) was of atmospheric origin and was obtained by transfer of fixed N by cowpea grown in association with maize. Under greenhouse conditions gram and summer and monsoon season cowpea have been found to contribute 14%–20%, 16% and 32% of the total N uptake by associated wheat and summer and monsoon maize crops, respectively. Inoculation of cowpea seeds with Rhizobium increased both the amount of N fixed by cowpea and transferred to maize in intercropping system. |
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Keywords: | Cereal-legume intercropping N fixation Transfer of legume N Rhizobium inoculation |
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