Ithaka Institut

Carbon Fertilizer

Parallel to our compost trials with biochar, Ithaka has been researching how to charge biochar using plant nutrients. We started with liquid mineral fertilizer and progressed to organic carbon fertilizers using waste from livestock farming and food processing. As biochar is an excellent carrier material for volatile nutrients, it seems ideally suited to design organic slow release fertilizers providing an excellent way to manage agronomic nutrient cycles.

When we started in 2011 to load biochar with high amounts of liquid NP-fertilizer and tested them in pod trials, we could prove reduced nutrient leaching after simulated strong rain events. When we planted a second culture (paprika after radish) in the same pods without additional fertilization, plant growth was significantly improved in the biochar treatments (see image). From an economic point of view, the difference in growth might have been not relevant as some additional fertilization would have been cheaper than the price of biochar that saved some mineral fertilizer. However working with low amounts of nutrient enhanced biochar [1 t per hectare]  applied as slow release fertilizer close to the roots every year seems very promising when viewed from both an economic and ecological perspective. 

paprika.jpg paprika.jpg

Next we focused on organic plant nutrients and started multiple tests with a wide variety of nutrient rich biomass wastes including: liquid animal manure, urine, feathers, yeasts, wool, vinasse etc. Over the past four years we have developed a panoply of organic carbon fertilizer that can be produced commercially or manufactured by farmers themself all over the world. One of our favourites is the sheep wool, vinasse, pyrolyse ash, biochar pellets with 7% Norg / 6.5% P2O5 / 6% K2O :