TY - JOUR
T1 - Biochar phosphorus release is limited by high ph and excess calcium
AU - Buss, Wolfram
AU - Assavavittayanon, Kamonchanard
AU - Shepherd, Jessica G.
AU - Heal, Kate V.
AU - Sohi, Saran
N1 - Publisher Copyright:
© American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.
PY - 2018/9/1
Y1 - 2018/9/1
N2 - Aside from its use for improving soil properties, biochar is increasingly promoted as a direct nutrient provider for sustainable recycling of waste materials. However, incomplete understanding of the interacting factors that determine P release from biochar may limit the efficiency of P recycling from biochar to soil. In particular, the contrasting pH of biochar and soil need to be considered. In this study, soil-free biochar (rice [Oryza sativa L.] husk, 700?C) extractions were performed under different pH (4.6-9.9) and extractant conditions to test how solution composition affects biochar P release. When solution pH was in the range of 7.6 to 8.6 and excess Ca was present in the solution or in biochar, P release was low-only 1 to 7% of the total P was released compared with ?20% under most other conditions. Importantly, we demonstrate that biochar total Ca concentration is closely related to P availability (R2 = 0.76) and could be used to predict biochar P release. The results suggest that for maximum P release, low Ca concentrations in biochar and (soil) solution are needed and/or a pH <7.5 at the soil-biochar interface. This novel understanding will help engineer sustainable biochar fertilizers optimized for P provision.
AB - Aside from its use for improving soil properties, biochar is increasingly promoted as a direct nutrient provider for sustainable recycling of waste materials. However, incomplete understanding of the interacting factors that determine P release from biochar may limit the efficiency of P recycling from biochar to soil. In particular, the contrasting pH of biochar and soil need to be considered. In this study, soil-free biochar (rice [Oryza sativa L.] husk, 700?C) extractions were performed under different pH (4.6-9.9) and extractant conditions to test how solution composition affects biochar P release. When solution pH was in the range of 7.6 to 8.6 and excess Ca was present in the solution or in biochar, P release was low-only 1 to 7% of the total P was released compared with ?20% under most other conditions. Importantly, we demonstrate that biochar total Ca concentration is closely related to P availability (R2 = 0.76) and could be used to predict biochar P release. The results suggest that for maximum P release, low Ca concentrations in biochar and (soil) solution are needed and/or a pH <7.5 at the soil-biochar interface. This novel understanding will help engineer sustainable biochar fertilizers optimized for P provision.
UR - http://www.scopus.com/inward/record.url?scp=85055420030&partnerID=8YFLogxK
U2 - 10.2134/jeq2018.05.0181
DO - 10.2134/jeq2018.05.0181
M3 - Article
SN - 0047-2425
VL - 47
SP - 1298
EP - 1303
JO - Journal of Environmental Quality
JF - Journal of Environmental Quality
IS - 5
ER -