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المنتدى العالمي المعني بالأمن الغذائي والتغذية

Re: Addressing water scarcity in agriculture: how can indigenous or traditional practices help?

Bill Butterworth
Bill ButterworthLand Research LtdUnited Kingdom

Water scarcity and Closed Loop Recycling of Wastes

High organic matter soils are reservoirs for water and that reservoir can be made bigger thus making irrigation water go 5 or even 10 times further. As the world gets more populated, it produces more agricultural and urban wastes. As it gets richer, it produces more urban wastes. For the human race to survive, we have to recycle these wastes. Most, if not all crop wastes, and many (most in some areas) urban wastes can be recycled using aerobic digestion, i.e. “composting” and TAD (Thermophilic Aerobic Digestion – pumping air in to raise the temperature). It is easy to accept that crop wastes from farming, or green wastes from urban gardens can be composted, but so can many industrial wastes.

Take hard plastics out of consideration, they are difficult but many plastics can be successfully recycled. For example, urea-formaldehyde is the “glue” used to make boards for furniture manufacture and discarded chip-board and MDF (Medium Density Fibreboard) and, when shredded, are a very useful source of Nitrogen fertiliser and are helpful in composting other materials. Another example is a “base” plastic (used to manufacture a wide range of glues and consumer product plastics) is PVA – Polyvinyl alcohol. This is “rocket fuel” for the micro-organisms in a compost heap but it is not easy to handle. It is liquid at temperatures above 60 or 70 degrees C but becomes progressively sticky as it cools.

Much easier to handle are materials such as crop residues, green wastes from urban gardens or city arboricultural management, cardboard and tissues and some industrial wastes. A good source of Nitrogen fertiliser is sewage and thorough composting above 60 degrees C will control pathogens. (Turn the heap every few days until it gets to 60 degrees, turn again and get up to 60. Three or four times up to 60 will dramatically reduce pathogen transfer risk.)

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