I recommend the ratio of biochar to solid nutrient source of 1:1. For example, 10kg biochar mixed with 10kg manure.

…but you can find your own ratio depending on what you have available.

A lot of biochar

+ Pro: You have less material to incooperate into your soil. You need around 500g of biochar per square meter. If you add a lot of the nutrient source you end up having to add far more then 1kg of the mix per square meter of soil.

– Con: If you have a lot of your biochar and very little of your nutrient source it can happen that the biochar does’t charge all the way. It makes it less effective the first time. You can always add a nutrient source as a top dressing and the nutrients will go into the soil and get stored by the biochar.

A lot of the nutrient source

+ Pro: Your biochar will be fully charged for sure! It will have the full effect right from the beginning. Any additional nutrients will still benefit your plants. It makes sense to have more of your nutrients source if biochar is used as a bedding for livestock farming.

– Con: You need to incooperate a lot of the mix to get 500g of biochar on every square meter. The additional nutrients can’t be taken up by the biochar and will easily be washed away. It might be more expensive to add more of the nutrient source.

I have heard people use any ratio between 4:1 and 1:4.

Let the biochar and solid nutrient source sit for min. 2 weeks to fully charge.