Biochar and Other Organic Carbon Amendment of a Coastal Loamy Sand.

We tested 12 organic sources as amendments for E horizon or a mixture of E and Bt horizons of a southeastern Coastal Plain loamy sand. Amendments were intended to increase carbon content and improve soil physical/chemical properties. Amendments included biochar, cellulose, corn stalk, corn starch, cotton hull, cotton meal, manure residual, peanut hull, poultry litter, soybean plant, wheat straw, and wood shavings. Amendment-soil mixtures of about 1% OC content were allowed to incubate for 60 days. Over the course of the experiment, cellulose, corn stalk, and corn starch gave the greatest improvement in aggregation; the control, peanut hull, poultry litter, wood shavings, and biochar gave the lowest. Cotton meal and poultry litter had the highest carbon dioxide flux at the soil surface; biochar had the lowest. Cotton meal, poultry litter, and cotton hull had the highest amount of dissolved organic carbon leached; the control and biochar had the lowest. Biochar, wood shavings, and corn starch had the highest penetration resistances; cellulose and cotton meal had the lowest. Poultry litter and manure residual had the highest improvement in water holding capacities; cellulose, biochar, and soybean plant had the lowest, though all were better than the control. The E and Bt horizon mix essentially added clay which improved all parameters for most treatments. All treatments improved the soil in one way or another. Biochar retained the most carbon throughout the incubation period.