Nitrate and Dissolved Organic Carbon Release in Sandy Soils at Different Liquid/Solid Ratios Amended with Graphene and Classical Soil Improvers

Abstract

This study emphasizes the importance of employing parallel batch tests with different liquid/solid (L/S) ratios to assess their dissolution mechanisms. Changes in physicochemical parameters (electrical conductivity, pH, and oxidation-reduction potential), as well as the sorption/desorption of dissolved organic carbon (DOC) and nitrate (NO3−) due to graphene addition in a calcareous sandy soil (CS) and in a siliciclastic riverine sandy soil (SS) were assessed via batch experiments at different L/S ratios. Graphene’s production is growing at a great pace, so it’s important to test methods to reuse graphene wastes. The results of soil batch experiments mixed with graphene were compared with classical soil improvers (compost, biochar, and zeolites). The batches were performed using the saturation soil extraction method with deionized water as a proxy of rainwater. The contact time was 48 h. At the end of the experiment, water samples were collected to be analyzed for NO3−, DOC, DIC, Ca, and Mg. Graphene did not alter the physiochemical parameters of both soils. Moreover, its addition did not trigger any NO3− increase respect to control and to other improvers. Biochar increased EC and pH beyond recommended limits for most crops’ growth in both soils. As expected, compost addition produced the highest NO3− release.

Effects of Graphene on Soil Water-Retention Curve, van Genuchten Parameters, and Soil Pore Size Distribution—A Comparison with Traditional Soil Conditioners

“…Although graphene was compared to traditional soil improvers in previous studies [23][24][25]31], in this study, for the first time, changes on soil physical characteristics were evaluated after graphene had been applied to the soil. The previous studies were more focused on nutrient leaching and solute transportation without considering the effects on soil porosity, water-retention curve, and soil bulk density.…”

“…To limit soil degradation and to improve the soil physical characteristics, different soil conditioners, both organic and inorganic, may be used as soil amendments [18]. Soil conditioners can improve soil's hydrophysical characteristics, quality, and fertility [19][20][21][22][23][24][25] Biochar, compost, and zeolites are the most common soil conditioners used for altering physical, chemical, and biochemical soil properties [26][27][28][29][30][31][32][33][34][35]. Biochar presents various positive functions in agricultural applications and has gained much attention in recent years [36][37][38].…”

“…Although graphene production is still very challenging, and we are still far from a largescale process, it has boomed exponentially since 2004, so it is very likely that graphene production scraps and graphene-based waste will increase in the coming years [47]. On this basis, and given that recent studies showed that the application of graphene to soils did not lead to an increase in nutrients or heavy-metal leaching [23,24,30,31], it is important to properly investigate its effects on various soil types to understand if graphene-based scraps could be eventually employed in agricultural systems, including graphene in an appropriate circular-economy scheme [48].…”

Spatial differentiation of soil nutrients and their ecological chemometrics based on geographic detector in National Agricultural Park of Tangchang, Southwest China

“…Due to the impacts of various natural and human factors (such as fertilization, land use change, rain water erosion and soil microbial activities, etc. ), soil nutrients show obvious spatial heterogeneity [ 4 – 7 ], which causes uncertainty to the results of land quality evaluation. Therefore, a better understanding of soil TOC N, P, K levels and their spatial variability and their influencing factors is necessary to evaluate soil productivity, guide nutrient management, assess potential environmental pollution and understand biogeochemical cycle.…”

Assessing the Effect of Intensive Agriculture and Sandy Soil Properties on Groundwater Contamination by Nitrate and Potential Improvement Using Olive Pomace Biomass Slag (OPBS)

“…Nowadays, nanotechnology has the potential to offer solutions for agricultural challenges such as boosting nutrient utilization efficiency, mitigating heavy metal toxicity, and efficiently improving soil fertility [23,24]. Alessandrino et al [25] investigated the ability of graphene to reduce the concentration of nitrate in sandy soils and concluded that, unlike other soil improvers, graphene can stimulate the denitrification process in soil. The use of biochar in reducing soil contamination has been extensively studied during the last years [26][27][28][29].…”