The Nitrogen Transfer Between Plants: An Important but Difficult Flux to Quantify
Citation
Henning Hogh-Jensen, The Nitrogen Transfer Between Plants: An Important but Difficult Flux to Quantify: .
Summary
The exchange of nutrients, nitrogen in particular, between closely associated plants has attracted considerable interest due to its importance in agroecosystems under low external nutrient-input management. The intuitive observation of farmers that grasses benefit from near associations with clovers has not been easy to quantify, mainly because (i) the net effect is measured against large background fluxes, and (ii) excluding one species from one agroecosystem change the system fundamentally. The study of Moyer-Henry et al. (pp. 7–20 in this issue) approaches this problem elegantly by choosing a soil with a relatively low background mineralisation of nitrogen, while maintaining the same species in the system, although in one case [...]
Summary
The exchange of nutrients, nitrogen in particular, between closely associated plants has attracted considerable interest due to its importance in agroecosystems under low external nutrient-input management. The intuitive observation of farmers that grasses benefit from near associations with clovers has not been easy to quantify, mainly because (i) the net effect is measured against large background fluxes, and (ii) excluding one species from one agroecosystem change the system fundamentally. The study of Moyer-Henry et al. (pp. 7–20 in this issue) approaches this problem elegantly by choosing a soil with a relatively low background mineralisation of nitrogen, while maintaining the same species in the system, although in one case as a non-nodulating variety. Their study confirms that substantial inter-plant Nitrogen transfer occurs. The study does, however, also raise the old question of direct and/or indirect transfer pathways (Virtanen et al., 1937; Wilson and Wyss, 1937). The 15N-natural-abundance technique may not be accurate enough to give reliable data on N fluxes, because it is even more sensitive than 15N-isotope dilution techniques to inhomogeneous distributions of tracers and roots (Luxhøj et al., 2003). The use of dual or triple tracers have been used in other studies (Kuzyakov, 2001) but it would be appropriate to apply direct plant labelling techniques using dual or triple tracers to obtain accurate information on this important process under field or semifield conditions.
Published in Plant and Soil, volume 282, issue 1-2, on pages 1 - 5, in 2006.