Effects of concentration-dependent graphene on maize seedling development and soil nutrients

The long-term use of chemical fertilizers to maintain agricultural production has had various harmful effects on farmland and has greatly impacted agriculture's sustainable expansion. Graphene, a unique and effective nanomaterial, is being used in plant-soil applications to improve plant nutrient uptake, boost fertilizer use, and reduce chemical fertilizer pollution by relieving inadequate soil nutrient conditions and enhancing soil absorption of nutrient components. We investigated the effects of graphene fertilizer on nutrient content, maize growth, and soil physicochemical parameters. In each treatment, graphene concentration gradients (0, 25, 50, 100, and 150 g·kg − 1 ) were applied in two distinct layers to the soil (single-layer and few-layers). Soil aggregates, soil accessible nutrients, soil enzyme activity, plant nutrients, plant height, stem thickness, dry weight, and fresh weight were all measured throughout maize growth to V3 stage. Compared to the control (0 g·kg − 1 ), we found that graphene increased the percentage of large agglomerates (0.25-10 mm) in the soil and significantly increased the geometric mean diameter (GMD) and mean weight diameter (MWD) values of > 0.25 mm water-stable agglomerates as the increase of concentration. Soil available nutrient content (AN, AP, and AK) increased, peaking at 150 g·kg − 1 . Graphene boosted nutrient absorption by maize plants, and aboveground total nitrogen (TN), total phosphorus (TP), and total potassium (TK) contents rose with the increasing application, which raised aboveground fresh weight, dry weight, plant height, and stalk thickness. The findings above confirmed our prediction that adding graphene to the soil may improve maize plant biomass by enhancing soil fertility and improving the soil environment. Given the higher manufacturing cost of single-layer graphene and the greater effect of few-layer graphene on soil and maize plants at the same concentration, single-layer graphene and few-layer graphene at a concentration of 50 g·kg − 1 were the optimal application rates.