Nitrogen and carbon transformations, water use efficiency and ecosystem productivity in monocultures and wheat-bean intercropping systems

摘要: Enhancing soil organic carbon (SOC), nitrogen (N) and water use efficiency (WUE) are significant challenges in intensive wheat production. An intercropping system combining grain legumes may help maintain SOC, mineral N WUE while also providing an opportunity to sequester (C) low input systems. We grew (Triticum aestivum cv. ‘Scarlet’) as a monoculture intercropped with either common bean (Phaseolus vulgaris ‘Red Kidney’, or ‘Black Turtle’), fava (Vicia faba ‘Bell’) rows of 1:1, 2 wheat: 1 broadcast arrangement without fertilizers for 2 years assess the effects genotype spatial on biological fixation seasonal transfer, WUE, gross ecosystem photosynthesis (GEP), net productivity (NEP). Stable isotope methods (13C 15N natural abundance) were used quantify C within plant system. Field CO2 exchange measurements dynamic closed transparent chamber connected portable analyzer. Intercropped plots had higher percent derived from symbiotic N2 fixation, increased accumulation compared monocultured wheat. The Bell intercrops showed nodulation (60–80 % more nodules) (10–12 % higher) beans resulting 74 kg N ha−1 biologically 1:1 arrangement. highest rate N-transfer (13 %) was observed wheat-fava combination when planted All accumulated shoot biomass (1:1 arrangement) accumulating (34 kg N ha−1, i.e., 176 % (214 g C m−2 year−1, 26 % higher). fixed most (i.e., greatest GEP) during mid-growth stage (50 days after seeding prior flowering) however, displayed NEP sequestering at daytime average 208 mg C m−2 h−1 7 % than plots). Intrinsic wheat, indicated by δ13C, improved grown Red Kidney. This study demonstrated that is effective strategy achieve greater transfer counterparts, monocultures areas C. Furthermore, productive 2:1 mixed planting arrangements.