Biochar and compost are natural partners. Compost brings nutrients and life; biochar gives them a permanent home. Together they build the kind of living, self-sustaining soil that organic and natural farming systems depend on. Here is how to use them together.
Why organic systems need durable organic matter
Organic and natural farming systems feed the soil rather than the plant. Without synthetic fertilizer, crops depend on nutrients released by soil organic matter and the soil food web. That makes organic matter the engine of the system, and in a hot climate it burns quickly. Compost and manure applied this season are largely consumed by next year, so organic farmers have to keep adding large volumes just to stand still.
Biochar adds a durable component that does not burn away. It keeps holding water and nutrients and hosting microbes long after the compost it came with has been consumed.
Charge it first
Fresh biochar has a vast, empty, absorbent surface. Put straight into soil, it can take up nitrogen and water before it starts releasing them, and growers sometimes see slower early growth as a result. In an organic system, where nitrogen is often the limiting nutrient, this matters.
The answer is to charge biochar before use. Blending it into compost, liquid manure or a fermented input such as jeevamrut lets its surfaces load up with nutrients and organic compounds and lets microbes colonise its pores. Research on co-composted biochar found that it develops an organic coating that holds nutrients and water, and that it captures nitrate and releases it slowly to plants.
Co-composting: the best way to charge it
The most effective method is to add biochar to the compost heap at the start, rather than mixing it in at the end. A share of around 5–20% biochar by volume is common. In the heap, biochar does not just get charged; it improves the composting itself. A review of biochar in composting found that it can speed up decomposition, reduce ammonia and other nitrogen losses, and reduce odour and greenhouse gas emissions from the heap.
Keep the heap moist, as biochar absorbs water, and turn it as you normally would. At the end you have compost and charged biochar in one product, ready for the field.
Other ways to charge biochar
If you are not composting, soak biochar for one to two weeks in diluted cattle urine, manure slurry, jeevamrut, vermiwash or diluted wood vinegar, stirring occasionally. Or mix it into farmyard manure while it is stored. Biochar can also be added to animal bedding and poultry litter, where it absorbs moisture and ammonia and comes out fully charged when the litter is cleaned out.
A living amendment
Biochar-enriched compost carries both stable carbon and a diverse microbial community into the field. Our Biochar-Enriched Compost (BEC) blends premium biochar with vermicompost in a 1 : 5 ratio and is charged with beneficial microbes and micronutrients, so it is ready to apply without charging on the farm. The recommended rate is 2 tons per acre per year, worked into the top layer of soil before sowing.
Using biochar in the field
Apply charged biochar or BEC during land preparation and work it into the top 10–15 cm, or apply it in planting furrows, beds and pits where roots will grow. For orchards and plantation crops, apply it in a ring around the tree under the canopy. Because biochar persists, its effect builds over seasons; moderate annual applications are usually more practical than one heavy dose. Mulching on top keeps the soil covered and feeds the biology that biochar hosts.
Fit for certification
Biochar made from untreated plant biomass is a natural, minimally processed product, and organic farming standards in many countries accept it as a soil amendment. Requirements differ between standards and certifiers, however, and some specify the feedstock, production method or contaminant limits. If your farm is certified or in conversion, check with your certification body before using biochar or any new input, and keep the supplier's certificate of analysis on file.
A simple co-composting recipe
For a heap of about one ton, start with roughly 100–150 kg of biochar, moistened before use so it does not blow away and does not pull water out of the heap. Layer it with your usual green and brown materials, such as fresh crop residue, cattle dung and dry leaves or straw, sprinkling biochar between the layers. Water each layer until the material is damp like a wrung-out sponge.
Turn the heap after two to three weeks and again every couple of weeks, keeping it moist. Many farmers add jeevamrut or a microbial culture at the first turning. Depending on the materials and the weather, the compost is usually ready in two to three months, when it is dark, crumbly and smells of earth rather than ammonia.
Biochar in natural farming practices
Biochar fits easily into the practices many Indian natural and organic farmers already use. It can be mixed into ghanajeevamrut, the solid fermented input made with dung, jaggery, pulse flour and soil, before it is dried and broadcast. It can be added to the bed mixture for vegetables and nurseries, to planting pits for fruit trees, and under mulch, where the moisture and organic matter keep its biology active. For seedlings, a small share of charged biochar in the nursery mix gives young roots a well-aerated, moisture-holding medium from the start.
In kitchen gardens and terrace farms, a handful of charged biochar mixed into each pot or grow bag along with compost and cocopeat keeps containers from drying out between waterings. Wherever it is used, the principle is the same: charge it first, place it where roots grow and keep feeding the soil with organic matter.
Mistakes to avoid
Do not apply large amounts of dry, uncharged biochar just before sowing a nitrogen-hungry crop. Do not spread it dry on a windy day; moisten it first. Do not rely on biochar alone to feed crops; it improves the soil's ability to hold and supply nutrients, but the nutrients still have to come from compost, manure, green manures or other permitted inputs. And do not use char of unknown origin, which may carry contaminants.
What to expect
Biochar is not a quick fix. In the first season, the benefit of charged biochar or BEC usually comes mostly from the compost. Over the following seasons, as biochar ages in the soil and organic carbon builds, growers typically see better water-holding, easier tillage, stronger crops in dry spells and a soil that responds better to every organic input. Test your soil before you start and every few seasons to track the change.
Above all, keep the soil fed. Biochar gives organic matter and soil life a permanent home, but it is the steady supply of compost, residues, mulch and living roots that fills that home. Organic farmers who combine biochar with these practices are building a soil that keeps getting better with every season, holding more water, more nutrients and more carbon than the soil they started with.
Sources and further reading
Sanchez-Monedero, M. A., Cayuela, M. L., Roig, A. et al. (2018). Role of biochar as an additive in organic waste composting. Bioresource Technology 247, 1155–1164.
Kammann, C. I., Schmidt, H.-P., Messerschmidt, N. et al. (2015). Plant growth improvement mediated by nitrate capture in co-composted biochar. Scientific Reports 5, 11080.
Hagemann, N., Joseph, S., Schmidt, H.-P. et al. (2017). Organic coating on biochar explains its nutrient retention and stimulation of soil fertility. Nature Communications 8, 1089.
Schmidt, H.-P., Kammann, C., Hagemann, N. et al. (2021). Biochar in agriculture: a systematic review of 26 global meta-analyses. GCB Bioenergy 13, 1708–1730.
Lehmann, J. & Joseph, S. (eds.) (2015). Biochar for Environmental Management: Science, Technology and Implementation, 2nd edition. Routledge.
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