Background: Lentil (Lens culinaris) is a major rainfed crop cultivated in Bundelkhand region and Malabar Neem (Melia dubia), a fast-growing tree species of significant economic and ecological importance. This study underscores the ecological benefits of optimized tree spacing with lentil varieties in agroforestry systems for Bundelkhand region. Methods: The present study entitled was conducted during the year 2023-2024 employed a split plot design with four levels of tree spacings under main plot and two levels of lentil (Lens culinaris) varieties under sub-plot with three replications. Growth and yield analysis of lentil varieties was estimated along with effect of tree spacing on soil properties. Result: The results revealing that from main plot, the sole cropping (G0) and IPL 316 lentil variety (V1) from sub-plot consistently outperformed intercropped treatments as it exhibited highest plant growth parameters, shorter number of days to 50% flowering and maturity along with higher yield attributes compared to the intercropped treatments. Yield decreased with increasing tree density, with the lowest values under the agroforestry system spaced at 5 m x 3 m (G3) spacing. However, intercropping improved soil health, with the highest soil physico-chemical properties and microbial activity recorded in the agroforestry system spaced at 5 m x 3 m (G3) spacing. Despite lower yields, intercropping promoted long-term soil sustainability. Overall, IPL 316 (V1) was the best-performing variety and agroforestry with optimized tree spacing improved soil fertility in semi-arid regions.

Nitrogen management is an important component of legume-based agroforestry, particularly where mineral nitrogen inputs and biological nitrogen acquisition interact. The present study evaluated contrasting mineral nitrogen and Rhizobium management treatments in a shisham (Dalbergia sissoo Roxb.)–jack bean (Canavalia ensiformis (L.) DC.) agroforestry system under the semi-arid conditions of Bundelkhand, India. The experiment was conducted during 2022–2023 and 2023–2024 at the Forestry Research Farm, Rani Lakshmi Bai Central Agricultural University (RLBCAU), Jhansi, India, using six treatments in a randomized complete block design with four replications. The present study evaluated the effects of contrasting mineral N levels and Rhizobium inoculation on jack bean growth, yield, nodulation and N uptake, together with shisham growth and soil N status, under a semi-arid agroforestry system. The treatments comprised sole jack bean with 0 and 100% recommended nitrogen, shisham–jack bean with 0, 50 and 100% recommended nitrogen, and Rhizobium-inoculated shisham–jack bean without mineral nitrogen. Nitrogen management had a considerable impact on the growth, production, nodulation, and nitrogen concentration of jack beans. The sole jack bean receiving 100% of the recommended N (T₂) exhibited the significantly highest plant height (108.75 cm), number of pods per plant (11.63), seeds per pod (7.70), and seed yield (899 kg ha⁻¹), whereas the shisham–jack bean system with 100% recommended nitrogen (T₅) yielded a similar seed output of 876 kg ha⁻¹. Rhizobium-inoculated shisham–jack bean without mineral nitrogen (T₆) showed the most significant nodulation (37.35 nodules per plant), nodule dry weight (303.25 mg plant⁻¹), seed nitrogen concentration (2.98%), soil NH₄⁺-N (10.15 mg kg⁻¹) and NO₃⁻-N (6.68 mg kg⁻¹). Total nitrogen concentration by plants was significantly highest in T₅ (53.63 kg N ha⁻¹) and was statistically at par with T₂ and T₆. The growth and biomass accumulation of shisham were similarly maximized in T₅, which achieved a tree height of 5.31 m, a diameter at breast height of 8.99 cm, and a total biomass of 9.60 Mg ha⁻¹. The findings indicate that suitable mineral nitrogen supplementation augmented productivity in the shisham–jack bean system, but Rhizobium inoculation enhanced nodulation and was associated with greater plant N concentration and soil mineral N under zero mineral-N conditions.