Sweet Sorghum and Upland Rice: Alternative Preceding Crops to Ameliorate Ethanol Production and Soil Sustainability Within the Sugarcane Cropping System

The objective of this study was to assess the effect of preceding crops (soybeans, sunn hemp, upland rice, and sweet sorghum) on the succeeding sugarcane yield, total bioethanol production, and soil chemical properties within the sugarcane cropping system. Treatments with upland rice and sweet sorghum provided the greatest increase in soil available P, compared to uncultivated land (control) at the final sampling, preceding the sugarcane harvest. Treatments effects were not significantly different for soil organic matter. At sugarcane harvest, the upland rice treatment provided the highest cane yield compared to the unplanted land, yet was not significantly higher than the yield of the sweet sorghum treatment. The highest sugarcane ethanol yields were observed in the sweet sorghum-sugarcane and upland rice-sugarcane treatments. However, the total ethanol yield in both preceding and succeeding crops was found to be highest in the sweet sorghum treatment, followed by the upland rice treatment. Upland rice proved to be most suitable for farming systems which emphasized food security, whereas sweet sorghum was most desirable for farming systems which emphasized alternative biofuel production. Both crops improved the sustainable production of soil and sugarcane.