The present study was designed to assess the effect of soil fertility levels on leaf quality of Morus alba L. plantations (denoted by S1, S2, and S3) growing on different soil nutrient status in Mizoram. Soil samples (0–15 cm depth) were collected from 5 random locations from each site and analyzed for physico-chemical parameters. Further, mature M. alba leaves were randomly collected from different locations at the site and proximity analysis was conducted. The soil properties (i.e. soil total carbon, SC; total nitrogen, TN; available phosphate, Pavail; exchangeable K; Kexch, and microbial biomass carbon, MBC) in these sites were in the order: S3 > S2 > S1. All soil properties were significantly different in these sites except TN, Pavail and Kexch values, but they did not differ significantly in sites S2 and S3. Proximity analysis showed high moisture and protein contents (i.e. 69.02% and 157.8 mg g−1) and (i.e. 68.89% and 148.4 mg g−1) in S2 and S3, respectively, compared to S1 (68.3% and − 126.4 mg g−1). However, crude fiber, ether extract, total ash and acid insoluble ash contents were significantly higher in S1 compared to S2 and S3. Soil chemical properties were significantly (p < 0.01) positively correlated with crude protein and leaf moisture contents, whereas, significant (p < 0.05 and 0.01) negative correlations were observed between soil chemical properties and remaining leaf proximity parameters. It is concluded that soil nutrient content significantly affects the quality of M. alba leaves. Therefore, proper soil fertility management through periodical assessment is recommended for the production of quality leaves of M. alba to have better silk production in the region. © 2022, The Author(s) under exclusive licence to Society for Plant Research.