Synthesis of an eco-friendly nanocomposite fertilizer for common bean based on carbon nanoparticles from agricultural waste biochar

The burning of agricultural waste is a major cause of environmental pollution. In this study, we sought to prepare biochar from agricultural waste as a source material for the preparation of carbon nanoparticles(CNPs). Surface morphology, hydrodynamic particle size, and purity and crystallinity of CNPs were extensively investigated using transmission electron microscopy(TEM), zeta sizing, and X-ray diffraction(XRD) spectroscopy, respectively. The CNPs were subsequently immersed in a solution of potassium nitrate(KNO3) to prepare a CNPs/NK nanocomposite(CNPs loaded with nitrogen(N) and potassium(K)) as a nanocomposite fertilizer for common bean(Phaseolus vulgaris L.). The CNPs/NK nanocomposite was sprayed as a foliar fertilizer at 0, 10, 20, 30,and 40 mg L-1on common bean plants 25 d after sowing on a farm in Shebin El-Kom, El-Monifia, Egypt. The growth, yield, and quality of common bean were investigated during two successive growing seasons(2017 and 2018). The highest seed yields of 2.04 and 2.01 t ha-1and the highest values of growth parameters including plant height of 61.5 and 59.2 cm, number of leaves per plant of 35 and 35, number of flowers per plant of 83.3 and 82.7, and plant fresh weight of 148.7 and 152.8 g plant-1were obtained when using the CNPs/NK nanocomposite at a concentration of 20 mg L-1during the 2017 and 2018 growing seasons, respectively.