Wicking Beds An easy way to grow food at home, save water and offset some carbon

Solution

The wicking bed is a highly productive growing system which not only
produces more food from limited water, but also recycles waste organic material to provide plant nutrient and capture carbon.
The essence is to form an underground reservoir of water or pond contained by a waterproof container or liner below the surface.

Problems would arise if the underground pond was routinely filled by applying water from the surface. The water percolating down through the soil would absorb nutrients which would accumulate in stagnant nutrient rich water in the pond. This would soon become anaerobic, starved of oxygen forming a toxic putrid mess which would inhibit plant growth.

This is resolved in the wicking bed system water by applying water to the bottom of the pond where it is pulled upwards to the roots of the plant by surface tension or wicking action. The water is
now not stagnant but continuously moving from the base of the pond upwards to the roots. First in first out.

The system gives the plant access to a continuous supply of water. There is minimal loss of water from either soaking into ground or from surface evaporation. This makes the system highly water efficient however plants need more than water, they need a balance of water air and nutrients. Too much water is just as bad as not enough water. Root systems need oxygen. They also can emit gasses such as carbon dioxide and ethylene which act as growth
inhibitors.
The wicking worm bed system correctly managed achieves this balance of water, air and nutrients.
(excerpt from http://www.waterright.com.au/Wicking_worm_beds.pdf)