Carbon nanoparticles improve corn (Zea mays L.) growth and soil quality: Comparison of foliar spray and soil drench application

The use of carbon nanoparticles (CNPs) in agriculture to boost crop production provides alternative solutions to meet ever-increasing food demand. However, insufficient documentation of optimal application methods of CNPs present significant hurdles to its application in agriculture. To clarify how foliar spray and soil drench of CNPs affect corn growth and nutrient uptake, plant growth parameters and soil quality attributes were measured. The application of CNPs significantly increased plant height (21.4%), dry biomass of shoots (27.1%) and roots (56.6%), plant uptake of N (133%), P (41%), K (192%), Ca (209%), Mg (106%), Fe (59.6%), Mn (155%), Cu (105%), Zn (117%), and altered photosynthetic parameters and soil chemical and biochemical properties. Overall, the stimulatory effects of CNPs varied with application rates and methods, and foliar spray of CNPs at 400 mg L−1 and soil drench at 200 mg kg−1 were most efficient in improving corn growth and soil quality. Principal component analysis (PCA) indicated corn growth parameters were positively influenced by CNPs regardless of application methods, while soil quality attributes were mainly positively affected only by soil drench. The stimulated corn growth could be attributed to enhanced nutrient uptake, elevated photosynthesis, and improved soil quality. This study provided a comparative evaluation of CNPs on plant growth and soil quality improvement and generated guidelines for optimizing utilization of CNPs for agricultural use.