Reason 2: Biochar Significantly Increases Agricultural Productivity
Carbon is the most essential element of soil fertility. When organic matter is added to agricultural soils to increase carbon levels, most of it rapidly decomposes to carbon dioxide and escapes to the atmosphere. Only a very small percentage eventually becomes stable humic matter. Humification takes decades to centuries. It is a delicate process that requires the right mix of soil biota, climate and moisture. Undisturbed temperate forests are an ideal environment for humification.
Industrial agricultural practices - specifically the use of chemical fertilizers, pesticides and tillage - decrease levels of humic matter in soils. Most agricultural soils are now severely degraded. The ongoing loss of soil carbon is a significant sustainability problem that must be addressed if we are to have enough food to feed ourselves in the future. Agricultural productivity is decreasing because of a loss of soil fertility, while industrial agricultural inputs are becoming increasingly expensive and ineffective at maintaining yields.
Biochar provides a stable backbone of carbon that can increase the fertility of soils on a permanent, cumulative basis. Adding biochar is a much more efficient way to increase soil carbon levels and thus fertility because
a) all of the carbon is immediately available to enhance fertility,
b) virtually none of the stable carbon added to soil decomposes and
c) biochar has a very large internal surface area because of its highly porous structure.
The main mechanism through which carbon increases fertility is called "cation exchange capacity" or CEC. The majority of plant nutrients are positively charged ions, known as cations, and include nitrogen, potassium, calcium, and magnesium. Once it is exposed to oxygen, freshly produced biochar begins to form negatively charged sites on its surface known as "functional groups". Cations in the soil solution are attracted to these sites and collect on the external and internal surfaces of the biochar. These nutrients are then available to the plants when they need them. It has been demonstrated that properly formulated, biochar can have higher cation exchange capacity than humic matter.
The reason high cation exchange capacity is so important to soil fertility is that because without it, nutrients are leached down through the soil, out of the reach of plant roots. So because of its stability, high internal surface area and capacity to have many negatively charged sites on its surfaces, biochar is highly efficient at storing nutrients in the root zone of plants where they can access them.
Biochar also increases agricultural productivity via several other important mechanisms, such as its capacity to retain moisture and support the proliferation of mycorrihizal fungi in soils.
For biochar to develop a high cation exchange capacity, it is critically important that it is made correctly. Both the temperature and length of of "baking" time need to be controlled to optimum levels. Generally speaking, biochar should be produced at 450° C to at most 550° C for as long as necessary for this amount of heat to penetrate to the core of the particle, but no longer. Correct processing ensures that sufficient hydrogen and oxygen are retained in the char to form the OH functional groups necessary for cation exchange capacity.
Our biochar production devices are designed to optimally control both temperature and residence time, and to ensure heat is evenly distributed to all biomass particles used to make biochar. Next Reason