Biochar is a carbon-rich coproduct resulting from pyrolyzing biomass. When applied to the soil it resists decomposition, effectively sequestering the applied carbon and mitigating anthropogenic CO2 emissions. Other promoted benefits of biochar application to soil include increased plant productivity and reduced nutrient leaching. However, the effects of biochar are variable and it remains unclear if recent enthusiasm can be justified. We evaluate ecosystem responses to biochar application with a meta-analysis of 371 independent studies culled from 114 published manuscripts. We find that despite variability introduced by soil and climate, the addition of biochar to soils resulted, on average, in increased aboveground productivity, crop yield, soil microbial biomass, rhizobia nodulation, plant K tissue concentration, soil phosphorus (P), soil potassium (K), total soil nitrogen (N), and total soil carbon (C) compared with control conditions. Soil pH also tended to increase, becoming less acidic, following the addition of biochar. Variables that showed no significant mean response to biochar included belowground productivity, the ratio of aboveground : belowground biomass, mycorrhizal colonization of roots, plant tissue N, and soil P concentration, and soil inorganic N. Additional analyses found no detectable relationship between the amount of biochar added and aboveground productivity. Our results provide the first quantitative review of the effects of biochar on multiple ecosystem functions and the central tendencies suggest that biochar holds promise in being a win-win-win solution to energy, carbon storage, and ecosystem function. However, biochar's impacts on a fourth component, the downstream nontarget environments, remain unknown and present a critical research gap.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1111/gcbb.12037

Biochar and its effects on plant productivity and nutrient cycling: a meta‐analysis

Preparation, modification and environmental application of biochar: A review

Effect of biochar additions to soil on nitrogen leaching, microbial biomass and bacterial community structure

https://people.clas.ufl.edu/azimmer/files/Publication-pdf/Zhao-Zimmerman-13_Heterogeneity-of-biochar-properties-as-a-function-of-feedstock-sources-and-prod-temp.pdf

Heterogeneity of biochar properties as a function of feedstock sources and production temperatures.

Biochar application to low fertility soils: A review of current status, and future prospects

Biochar influences the microbial community structure during manure composting with agricultural wastes.

Chemical and biochemical characterisation of biochar-blended composts prepared from poultry manure.

Influence of biochar addition on the humic substances of composting manures.

The impact of cell division and cell enlargement on the evolution of fruit size in Pyrus pyrifolia.

In Japanese pear, the application of GA3+4 during the period of rapid fruit growth resulted in a marked increase in pedicel diameter and bigger fruit at harvest. To elucidate the relationship between pedicel capacity and fruit growth and to determine the main factor responsible for larger fruit size at harvest, fruit growth and pedicel vascularization after GA application were examined and the carbohydrate fluxes were monitored in a spur unit by non-invasive techniques using 13C tracer. Histological studies of fruit revealed that GA increased the cell size of the mesocarp but not the cell number and core size. The investigation of carbon partitioning showed that an increase in the specific rate of carbohydrate accumulation in fruit or the strength of fruit should be responsible for an increase of fruit weight in GA-treated trees. Observation of pedicel vascularization showed that an increase in pedicel cross-sectional area (CSA) by GA application mainly resulted from phloem and xylem CSA, but it is unlikely that an increase in the transport system is the direct factor for larger fruit size. Therefore, it can be concluded that larger fruit size resulting from GA application during the period of rapid fruit growth caused an increase in the cell size of the mesocarp and increased carbon partitioning to the fruit. Although GA is closely involved with pedicel vascularization, it seems that photosynthate accumulation in fruit is limited by the sink strength of fruit rather than by the transport capacity of the pedicel.

13C-photosynthate accumulation in Japanese pear fruit during the period of rapid fruit growth is limited by the sink strength of fruit rather than by the transport capacity of the pedicel

Kazuhiro Matsumoto

Papers

Biochar influences the microbial community structure during manure composting with agricultural wastes.

Chemical and biochemical characterisation of biochar-blended composts prepared from poultry manure.

Influence of biochar addition on the humic substances of composting manures.

The impact of cell division and cell enlargement on the evolution of fruit size in Pyrus pyrifolia.

13C-photosynthate accumulation in Japanese pear fruit during the period of rapid fruit growth is limited by the sink strength of fruit rather than by the transport capacity of the pedicel