The simultaneous assessment of nitrogen and water use efficiency by intercropped pea and barley under contrasted pedoclimatic conditions

Abstract Background and aims: Currently, there is a pressing need to study and improve both water and nitrogen (N) use efficiency (WUE and NUE). Surprisingly, this topic has not been adequately documented in recent literature, particularly within the context of intercropping systems. This study aims to assess the simultaneous changes in WUE and NUE through the implementation of rainfed pea-barley intercropping compared to their respective monocultures. Methods: Field trials were conducted over two growing seasons at four experimental sites characterized by varying soil and pedoclimatic conditions. WUE and NUE were measured in monoculture and intercropping involving pea and barley. Results: Our findings indicate that pea-barley intercropping had a more pronounced advantage over monoculture in terms of grain yield (+61%) and yield quality (+83%) compared to plant biomass (+35%), except for the site under dry conditions. Additionally, the results show that under higher rainfall conditions, intercropping exhibited the highest NUE values (5.07 kg grain N kg-1 soil N at sowing), while the highest WUE values (1.40 kg m-3) were observed under low-rainfall. Quantifying the relationship between WUE and NUE indicated a positive interaction for intercropping (r2 = 0.61, p ≤0.001) and pea monocrops (r2 = 0.36, p ≤0.01), but only when considering dry biomass at flowering stage. Conclusion: These advantages of pea-barley intercropping can be attributed to the optimized-use of N and water resources, considering their contrasting co-limitation under semiarid conditions.