Intercropping-driven nitrogen trade-off enhances maize productivity in a long-term experiment

Intercropping improves land productivity by exploiting species complementarities to achieve sustainable agriculture. Intercropping systems, therefore, require a nitrogen (N) management approach that matches temporal and spatial N supply with crop requirements. Present field-based study (started in 2013) explored the effects of intercropping of maize ( Zea mays L. ) with legumes [peanut ( Arachis hypogaea ) and soybean ( Glycine max )] and non-legumes [gingelly ( Sesamum indicum L. ) and sweet potato ( Dioscorea esculenta )] on maize productivity and N trade-off. Compared with maize monoculture, intercropping with gingelly, peanut, soybean, and sweet potato all significantly improved maize average yield (2013 and 2021), average N use efficiency (NUE), average N partial factor productivity (PFPN), and plant N uptake by 8–29%, 28–49%, 20–80%, and 16–35%, respectively. The N losses via ammonia volatilization and runoff in intercropping systems decreased by 12–19% and 11–43% respectively, compared with monoculture. Soil total N, inorganic N (NH 4 + -N and NO 3 - -N), and microbial biomass N (MBN) contents as well as the urease, β-1,4-N-acetyl-glucosaminidase (NAG), and leucine aminopeptidase (LAP) activities varied among different intercropping systems and maize growth periods. Maize productivity (yield, PFPN, and NUE) was positively correlated with plant N uptake (R 2 = 0.66–0.92, P < 0.001) and soil MBN content (R 2 = 0.41–0.47, P < 0.01), while it was found negatively associated with N losses (R 2 = 0.35–0.56, P < 0.05), soil N availability (R 2 = 0.27–0.67, P < 0.05), and NAG activity (R 2 = 0.36–0.55, P < 0.05). These findings collectively indicated that regulating the balance between soil N supply and plant N uptake in an intercropping system with low N fertilization could achieve high productivity. This study highlighted the importance of understanding the complex interaction between crop development and intercropping practices in improving maize productivity and N trade-off. • Intercropping increased average (2013 and 2021) maize yield by 8–29%. • Intercropping improved average NUE by 28–49% and maize N uptake by 16–35%. • N loss via ammonia volatilization and runoff decreased by 11–43% duo to intercropping. • Maize productivity was primarily related to plant N uptake, soil N dynamics and N loss. • Intercropping-driven plant-soil N trade-offs contributed to increased maize productivity.