I was drawn to Biochar because it seems like a "final solution" product, with the ability to do its good continuously for hundreds of years. This means I might be able to do something just once to improve soil and reduce the cost and work of soil amendments and watering.
What is biochar? Simply put, it is activated charcoal specially prepared for soil amendment. In the soil, biochar particles act like sponges, capturing and holding water and minerals. It is a perpetual habitation for soil bacteria that participate in the uptake of nutrients by plant root hairs.

Biochar promises to solve three soil problems at once and do it permanently.
1. Biochar holds water. My silt loam soil is very poor at this.
2. Biochar, being high grade organic carbon, captures, holds, and makes available to plants the soluble minerals that plants need. My soil is poor at this.
3. Biochar, as a porous wood product, is an organic habitat for soil bacteria and fungi that are essential in providing nutrients to the root hairs of the plants.

The idea of adding charcoal to the soil is rather new in the West. It has become the darling of soil scientists and its study has taken hold in agriculture colleges all over the world. Large scale production facilities are being designed and built, but by now there may be over 15 large plants in the USA turning waste wood products into biochar. The nice thing is that I could design and build a biochar stove to make it myself. In the winter 2014-15 I produced about 1.5 cubic yards of pulverized biochar in my back yard at almost no cash expense.

Research shows biochar has several effects in soil including:

Increased water infiltration and water holding capacity
Improved soil structure, tilth and stability
Increased cation exchange capacity (CEC)
Increased adsorption of ammonium, nitrate, phosphate, and calcium ions
Increased nutrient retention over ordinary organic matter
Improved soil pH buffering and stability
Increased soil biology and diversity

http://www.biocharnow.com/index.php/applications/specialty-agriculture
Enhanced, denser root development
Reduced fertilizer runoff, especially nitrogen and phosphorus
Reduced total fertilizer requirements
Decreased emissions of nitrous oxide by 50-80%

Here are some quotes from scientific papers that led me to adopt Biochar as a soil additive for my gardens.

"Biochar, also called black gold for agriculture, is being used increasingly in agriculture to mitigate climate change by sequestering carbon (C), improving soil properties and enhancing crop yield."
"Biochar is an amendment that can be used for enhancing soil water storage which may increase crop productivity."
"Biochar is a C-rich product distinct from charcoal and similar materials in that biochar is produced for the purpose of soil application as a means to improve its quality; to prevent nutrient leaching; to improve C storage; or to depurate the soil from pollutants."