Recycling waste, such as rice straw and water treatment residuals, is important to reduce harmful effects on the environment and to improve canola yield and soil quality in degraded soils. Nanotechnology for the production of nanomaterials from biochar and water treatment residues will be a future revolution for improving soil quality and increasing canola yield in degraded soil. Therefore, this study aims to identify the properties of some recycled nanomaterials, such as nanobiochar (nB) and nanowater treatment residue (nWTR), and their effect on the biological activity and productivity of canola in degraded soils. The results showed that the nWTR and nB contain many functional groups and minerals, and they also have high negative zeta potential. The addition of the studied soil amendments significantly improved microbial biomass carbon (MBC) and biological activity, which played a major role in increasing canola yield. The highest dehydrogenase (DHA) and catalase (CLA) activity was found in nWTR-treated soil at 50 mg kg−1, with increases of 32.8% and 566.7% compared to the control, respectively. The addition of nB greatly improved the growth of canola plants in the soil. This was evident from the increase in the weight of seeds, the weight of 1000 grains, the number of pods per plant, and the highest increase was for nB added at the rate of 250 mg per kg−1 soil. The addition of 50 mg kg−1 of nWTR gave the best results in seed yield by 150.64% compared to the control. These results indicate that recycled nWTR and nB are some of the best waste recycling treatments, in addition to good soil health, in increasing soil biology and canola yield in degraded soils. In the future, research on recycled nanomaterials should examine the residual effect they have on yield, soil quality, and soil fauna in the long term.

Nanotechnology is a promising science in the development and improvement of soil, raising its production capacity and recycling waste in a hastily manner. This study aims to investigate the properties of some recycled nanomaterials and their effect on the biological activity and productivity of canola in degraded soils. Measuring the spectroscopic and chemical properties of nanomaterials such as biochar (nB) and water treatment residuals (nWTR) and adding them at different rates to the degraded soil. The results showed that the FTIR and XRD spectra of nWTR and nB contain many functional groups (such as C = O, OH, C = C, C-H, Si-O-Al, and Si-O-Si) and minerals. Zeta potential of the nB and nWTR was − 31.08 mV and − 65.25 mV, respectively. Addition of nB or nWTR at different rates significantly improved canola yield. Seed weight of canola plant increased with increasing nB rate by more than 64%, while it decreased with increasing nWTR rate. Microbial biomass carbon (MBC) and the activity of dehydrogenase (DHA) and catalase (CLA) increased significantly in the treated pots with the addition of nB and nWTR at different rates. Our results suggested the possibility of adding reused materials in the form of nanomaterials to the degraded soils, which would have the ability to improve their properties and increase their yield.