Section 8
Chapter 7,984

Uptake of soil nitrogen by soybean as influenced by symbiotic nitrogen fixation or fertilizer nitrogen supply

Jensen, E.S.; Sorensen, L.H.

Soil Biology and Biochemistry 20(6): 921-926


ISSN/ISBN: 0038-0717
Accession: 007983734

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Nodulated and N2-fixing soybean plants (Glycine max. L.) grown in a pot experiment took up significantly more soil N (labelled with 15N) than non-nodulated control plants. The organic matter in the experimental soil was labelled with 15N during a previous incubation, and the pool of labelled inorganic N originated mainly from mineralizatin of organic matter. Addition of non-labelled ammonium or nitrate-N to non-nodulated plants did not increase their uptake of labelled soil N. Plants grown with the various N-sources exhausted the soil for KCl-extractable N to almost the same low concentration. Where non-nodulated plants were grown, 60-75% of the inorganic N initially present could be accounted for in plants an KCl-extracts at harvest. An amount corresponding to 98% of the KCl-extractable N initially present was found in nodulated plants and the pool of KCl-extractable N.

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