Biofuels 1 Carbon 1 Carbon sequestration 1 Chelation 1 Crops 1 Environmental benefits 1 Farm Crops 1 Fertilization 1 Geostatistical approach 1 Input 1 Metabolism 1 Negative correlation 1 Nitrogen fertilization 1 Nitrogen fertilizers 1 Organic carbon 1 Panicum virgatum 1 Plants (botany) 1 Soil 1 Soil carbon sequestration 1 Soil organic carbon sequestration 1 Soils 1 Spatial heterogeneity 1 Tripsacum 1 Tripsacum dactyloides Urea 1 agricultural land 1 bioenergy 1 bioenergy cropland 1 carbon sequestration 1 decomposition 1