Biochar and Mill Ash Use As Soil Amendments to Grow Sugarcane in Sandy Soils of South Florida.

The use of organic residues as amendments provides an option to improve sugarcane production in sandy soils located northwest of the Everglades Agricultural Area, while reducing waste and improving soil health. This study was conducted to determine the effect of mill ash and three biochars on sugarcane yield and sandy soil properties. Mill ash (AS) and biochars produced from hardwood yard waste (HY), barn shavings with horse manure (HM), and rice hulls (RH) were incorporated at 1% and 2% (by weight) to sandy soils in a lysimeter experiment. A control without amendment and an often-used commercial practice of mill ash applied at 6% (AS6) were also included. Results showed that RH2 and AS6 produced greater biomass and sucrose yield compared with the control. In addition, RH2 and AS6 increased, Mehlich-3 phosphorus and cation exchange capacity (CEC) compared with the control. While CEC remained constant with AS2 and AS6 applications, CEC significantly increased over time with RH2. Moreover, higher amendment applications increased soil organic matter and did not decrease over time, which suggests a positive influence for long term carbon sustainability and nutrient cycling in sandy soils. Overall, RH2 and AS6 have the most potential to be used as amendments in sandy soils of South Florida due to their positive effects on soil properties, which improved sugarcane yield. Future research should focus on the use of RH and AS amendments on long-term field-scale studies, and the economic feasibility of a single year application on plant and ratoon cane yields.