Ricardo A Lesmes-Vesga1, Amandeep Sharma1, Hardev Sandhu1 and Alan Wright2
1Agronomy Department. University of Florida, Institute of Food and Agricultural Sciences, Everglades Research and Education Center, 3200 East Palm Beach Road, Belle Glade, Florida 33430, USA; hsandhu@ufl.edu
2Department of Soil, Water, and Ecosystem Sciences, University of Florida, Institute of Food and Agricultural Sciences, Indian River Research and Education Center, 2199 S Rock Road, Fort Pierce, Florida 34945, USA
Lignocellulosic energy crops, such as energycane (sugarcane with higher fiber and lower sugar content), have the potential to supply one-third of the biomass required for the U.S. bioeconomy by 2030. Evaluating cost-effective, regionally tailored agronomic practices is crucial, especially considering the high yields of energycane on fallow croplands. Additionally, it is important to assess the energycane ecosystem services as it can mitigate nutrient losses and subsequent pollution given its high capacity to absorb elements such as nitrogen and phosphorus. This study evaluated energycane cultivar UFCP 84-1047 on fallow sandy soil (Spodosol), in a field previously used for citrus production in southeastern Florida. Four nitrogen and phosphorus rates were compared under a completely randomized block design with four replications. Biomass yield, soil, groundwater, and runoff water quality were assessed. Energycane yield was not different among treatments and stayed similar even when nitrogen and phosphorus rates were reduced to half of the recommended rates for sugarcane. Energycane lowers the nitrogen and potassium concentrations in deeper soil layers, and phosphorus in the shallower layer. Additionally, soil phosphorus and potassium availability declined in shallow soil under energycane, while these tended to increase in fallow plots. Nitrate and phosphorus concentrations in groundwater and runoff from fertilized plots under energycane were not different from fallow land. Energycane offers a feasible alternative for soils phytoremediation, as leaching of nitrogen and phosphorus fertilizations did not increase. Furthermore, lower nitrogen and phosphorus fertilization rates in Florida sandy soils did not affect energycane yields given its high nutrient-uptake efficiency. This field-scale trial for fallow lands serves as a model for converting large areas of abandoned citrus groves into sustainable energycane production systems, although further research is needed to validate these findings based on one year of data collection.