Legume-inclusive cropping is increasingly appreciated for enhancing crop yield and sustainability. However, their impacts on subsequent oilseed rape productivity under reduced nitrogen (N) inputs have not been well explored. In a five-year field rotation experiment, oilseed rape was cultivated with N fertilizer at zero (MN0), recommended (MN100), and 35 % reduction (MN65) following maize monoculture or preceding lablab (Lablab purpureus (L.) Sweet) intercropping in addition to MN65 (IN65). The productivity and stability of subsequent oilseed rape, and relevant indices of soil fertility and N cycling enzymes were investigated. Compared with the MN0 control, the MN100, MN65 and IN65 treatments increased the rapeseed yield by 0.7- to 1.2-fold. Compared with MN100, MN65 decreased rapeseed yield by 21 % and N uptake by 16 % on average across years. However, preceding lablab intercropping (IN65) recovered yield and N uptake. Treatment IN65 increased soil total N content by 7 % and organic matter by 10 % compared to the monoculture treatments, corresponding to 18–25 % increase in the soil quality index by preceding pulse intercropping. Moreover, in parallel with the increase in soil urease activity, the soil nitrate content in IN65 markedly increased by 18–123 % compared with that in the MN65 or MN100 treatments at most stages of oilseed crop growth. Principal component analysis revealed that the IN65 treatment was well distinguished from the three monoculture treatments, which was attributed primarily to soil nitrate, organic matter, nitrate reductase activity, and microbial biomass N. This enhanced N turnover and availability, in turn, largely contributed to N uptake and yield recovery of subsequent rapeseed crops under reduced N input. Consequently, the yield sustainability and stability of rapeseed following lablab intercropping were greater than those following monoculture, as evidenced by the higher sustainability index (64 % vs. 49 %) and lower variation (20 % vs. 32 %). Overall, these findings indicate that lablab and maize intercropping enhances positive legacies for subsequent rapeseed productivity under reduced N inputs.

中文翻译：

---

豆科植物和玉米间作在减少氮输入的情况下提高了随后的油菜产量和稳定性


豆类种植在提高作物产量和可持续性方面越来越受到赞赏。然而，在减少氮 （N） 投入的情况下，它们对后续油菜产量的影响尚未得到很好的探索。在一项为期五年的田间轮作试验中，在玉米单一栽培或之前的 lablab （Lablab purpureus （L.） Sweet） 间作加上 MN65 （IN65） 的基础上，用零 （MN0）、推荐 （MN100） 和减少 35% （MN65） 的氮肥种植油菜。研究了后续油菜的生产力和稳定性，以及土壤肥力和氮循环酶的相关指标。与 MN0 对照相比，MN100、MN65 和 IN65 处理使油菜籽产量提高了 0.7 至 1.2 倍。与 MN100 相比，MN65 多年来平均降低了 21% 的油菜籽产量和 16% 的氮吸收。然而，之前的 lablab 间作 （IN65） 恢复了产量和氮吸收。与单一栽培处理相比，IN65 处理使土壤总氮含量增加了 7%，有机质增加了 10%，相当于通过之前的脉冲间作使土壤质量指数增加了 18-25%。此外，在土壤脲酶活性增加的同时，在油籽作物生长的大多数阶段，与 MN65 或 MN100 处理相比，IN65 中的土壤硝酸盐含量显着增加了 18-123%。主成分分析表明，IN65 处理与 3 种单一栽培处理有较好的区别，后者主要归因于土壤硝酸盐、有机质、硝酸盐还原酶活性和微生物生物量 N。这提高了氮的周转率和可用性，反过来又在很大程度上促进了在减少氮投入的情况下后续油菜籽作物的氮吸收和产量恢复。 因此，lablab 间作后油菜籽的产量可持续性和稳定性高于单一种植后，较高的可持续性指数（64 % 对 49 %）和较低的变异（20 % 对 32 %）证明了这一点。总体而言，这些发现表明，在减少氮投入的情况下，lablab 和玉米间作增强了后续油菜籽生产力的积极遗产。