Add charcoal to soil before seeding/planting
Overall effectiveness category Evidence not assessed
Number of studies: 1
Background information and definitions
Charcoal can be added to soil to increase its fertility, carbon storage, and water retention. When charcoal is used for soil amendment it is commonly known as biochar. Charcoal has a long history of use as a fertilizer, and was used by pre-Colombian Amazonians to enhance soil productivity. Adding charcoal to soil can increase crop yield in agricultural systems (Jeffery et al. 2011), and so addition of charcoal to soil alongside seeding in grasslands may help to increase survival and growth of grassland plants.
The studies detailed in this intervention are direct tests of the effectiveness of adding charcoal to the soil before seeding or planting (e.g. by comparison with an untreated but seeded or planted plot). Studies that represent comparisons of seeding to unseeded plots can be found in the actions ‘Sow grass seeds’, ‘Sow grassland forb species’ or ‘Sow native grass and forbs’.
Jeffery, S., Verheijen, F.G., van der Velde, M. & Bastos, A.C. (2011) A quantitative review of the effects of biochar application to soils on crop productivity using meta-analysis. Agriculture, ecosystems & environment, 144, 175–187.
Supporting evidence from individual studies
A replicated, randomized, paired, controlled study in 2011 in a restored grassland in the Netherlands (Van de Voorde et al. 2014) found that addition of charcoal to soil before sowing seeds increased the cover of legumes, but did not alter the cover of grasses or other forbs or total plant biomass. Plots where charcoal was added to soil before sowing had higher cover of legumes (39%–41%) than those where no charcoal was added before sowing (14%). However, there was no significant effect of charcoal addition on cover of other forbs (charcoal: 86–90%; untreated: 93%), cover of grasses (charcoal: 6%; untreated: 8%), or total plant biomass (charcoal: 486–495 g/m2; untreated: 465 g/m2). In April 2011, six 4 x 4 m plots were treated with charcoal, produced from grass cuttings heated to either 400°C or 600°C, at a rate of 10 Mg/ha. Plots were paired with untreated plots. All plots were then rotovated and sown with a grassland seed mixture. In August 2011, vegetation cover was assessed in four 1 x 1 m quadrats/plot. In October 2011, vegetation was clipped in two 0.5 x 1 m quadrats/plot to determine plant biomass.Study and other actions tested