Manure Biochar As a Fertilizer Source for Ryegrass.

When processed via pyrolysis, livestock manures have the potential of providing energy and biochar.  Biochars that are high in carbon but low in nutrient content, such as wood, can be applied to soil in relatively large amounts.  This is in contrast to manure biochars.  They are high in nutrient content, especially potassium and phosphorus.  They must be applied in accordance with their nutrient supplying capacity.  This capacity will be affected by factors such as manure type and processing conditions.  In this greenhouse study, investigations involved five manure sources: swine; dairy; beef; feedlot; turkey; and poultry litter.  The biochars were produced at temperatures of 350°C or 700°C.  They were applied to a Norfolk sand that was low in phosphorus content at a rate to 150 mg of P per kg soil.  It was supplemented with 50 mg of N per kg of soil.  The soil was placed in small pots and seeded with ryegrass. The ryegrass was grown for approximately seven weeks. All of the biochars supported dry matter production equivalent to chemically applied phosphorus and potassium.  The poultry bichar was generally the best and the swine was generally the least effective.  The phosphorus in the biochar was accumulated similarly to the fertilizer treatment.  Moreover, the phosphorus remaining in the soil in the fertilizer treatment was similar to the equivalent biochar treatment.