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Estimating nitrogen transfer by foliar 15N-labeling in legume-non-legume associations
- Chalk, P.M., Smith, C.J.
- Biology and fertility of soils 1997 v.24 no.2 pp. 239-242
- Fabaceae, legumes, Poaceae, intercropping, plant nutrition, nitrogen, stable isotopes, isotope labeling, foliar application, nutrient uptake, estimation, equations
- We examined the basis for estimating the transfer of legume N to companion cereals or grasses in intercropping or pasture systems using the foliar 15N-labelling technique. Published data from three pot experiments were used to illustrate different methods for estimating N transfer. Yield-dependent and yield-independent methods based on measurement of the 15N enrichment of the whole legume biomass at harvest overestimate N transfer. Estimates of N transfer using a yield-independent method based on the 15N enrichment of the legume roots at harvest were inconsistent with estimates based on the isotopic composition of the whole plant. We propose a new mathematical concept for estimating the transfer of legume N based on measurement of the 'mean pool abundance' of the legume biomass during the period of N transfer.