Further studies on composting flour milling co-products

Abstract

Milling by-products, bran, wheatfeed and friction bran, were composed with water, waste wash water from starch production and carbon-rich waste products. The composted materials were tested by laboratory analysis. Materials produced in the previous year were tested as a lawn fertilizer and as a growing medium for tomatoes.

During composting, mass was lost in the form of carbon dioxide, and the dry matter was on average reduced to 40% of that originally present. The bran and wheatfeed, composted without the addition of other carbon sources, produced nutrient-rich materials. With wheatfeed added to paper waste, the compost produced maybe suitable for the growth of tomatoes.

Friction bran composted, but having less protein to start with, gave a material low in available nitrogen but still relatively high in potassium. The friction bran was difficult to wet up initially and required a greater addition of water for composting to commence than bran or wheatfeed. However, once the material had broken down the material was therefore much wetter than the others and difficult to handle.

Bran mixed with shredded banknotes composted well but a greater proportion of banknotes to bran would be needed to reduce the conductivity and make an acceptable growing medium.

The waste wash water had very little nutrient value and no real differences in composts made with either wash water or with mains water could be found.

An unreplicated trial of composted wheatfeed on lawn turf containing moss indicated that grass growth and colour were promoted and that moss smothered and thereby reduced in visibility.

Tomatoes were grown in pots containing composted bran and wheatfeed mixed with peat or woodfibre. The plants grew very well and showed that additional lime and inorganic fertilizers were unnecessary, and that liquid feeding could be delayed. The growing media contained 20% by volume of the composts with the bran compost releasing more nutrient than the wheatfeed. However, the wheatfeed mixes tended to be more balanced nutritionally and gave tomatoes of better quality.