Methods of Application to Date
The following is a collection of biochar application methods that have been attempted on a landscape scale to date.
If you know a a method that has been tried, but is not included on this website, please submit your information on the Contact Us page.
The application of biochar by hand is well known, but cannot be considered viable at scale due to labor intensity and human health concerns due to prolonged contact with airborne biochar particulates.
Tractor propelled lime spreader and disking
Several large scale biochar trials have been conducted using a tractor propelled lime spreader during application. While the technology lends itself to careful calibration of output, significant concerns surrounding environmental air quality and product loss due to wind and water erosion remain.
The deep banding of biochar has been successfully implemented in several wheat fields in Western Australia. This low-impact application method deposits biochar directly into the rhizosphere, and may be viable for previously established crops, and perennial cropping systems. However, relatively low rates of application are technically possible with one pass (3t per ha), and the process is relatively labor intensive. Additionally, issues with pneumatic clogging due to biochar particle size distribution and air quality remain.
Tractor propelled manure spreader
The mixing of biochar with composts and manures may reduce odors, and improve nutrient performance over time due to slowed leaching rates. Mixtures may be applied for uniform topsoil mixing, or top-dressed in vine or tree plantations without incorporation. While the airborne dust fraction would be minimized, the tonnages of biochar application may be relatively low per ha, and additional equipment would be needed to incorporate applied compost into topsoils thereby increasing costs and carbon footprint.
Tractor propelled poultry litter subsurfer
Much like the tractor propelled manure spreader, the subsurfer may lend itself to biochar compost mixtures. However, unlike the surface application achieved by the manure spreader, the subsurfer, much like the deep bander, deposits the mixture in the rhizosphere. The technology is still under development by the USDA-ARS, and it is unknown how well a subsurfer might perform for biochar application.
Trench and fill
Line trenching and backfilling may lend itself to high biochar application rates in soil for carbon sequestration while still increasing the agronomic performance of soils. While labor and carbon intensive, the combination of high saturation rates and improved agronomic productivity may make the practice viable. However, like deep banding and subsurfing, it is unknown how well biochar migrates vertically through the soil profile, and performance may deteriorate at small distances from the point of application.