Symbiotische N2 Fixierung und N–Bilanz von Soja unter Be-rücksichtigung der N-Rhizodeposition im DOK Versuch

Summary

Symbiotic N2 fixation (Nfix) and N-balance was determined from organic and conven-tional grown soybean in the DOK experiment (Switzerland). Nfix was calculated i) based solely on soybean aboveground N (AGN) and ii) additionally taking into account belowground N (BGN), comprising N in physical roots and N rhizodeposition. Nfix was averagely two times higher considering AGN and BGN, ranging from 22 g N m-2 (conventional manure) to 37 g N m-2 (conventional mineral). N balances were positive in all treatments, but with 2 – 7 g N m-2 based on AGN solely comparatively small. These values were exceeded fourfold when considering BGN ranging from 13 g N m-2 (conventional manure) to 21 g N m-2 (organic and conventional mineral).