CABBAGES AS A NUTRIENT SINK FOR FOOD PROCESSING BY-PRODUCTS

Abstract

The high nutrient needs of horticultural crops provide an opportunity for reuse of organic and high biochemical oxygen demand (BOD5) factory by-products as fertiliser. This nutrient recycling is a cornerstone of sustainable production systems. One such by-product, dunder from yeast production, was tested for its impact on cabbage production on a brown Vertosol soil in the Lockyer valley, Queensland. The high K content of raw and anaerobically fermented stable dunder may be a substitute for normal mineral potassium fertilisers. The trial was a factorial design (2x3x2) randomised complete block experiment with three replications. The treatments were: potassium rate (0 and 100 kg K ha); fertiliser type (K2SO4, raw dunder and stable dunder); and application method (100 % K at planting and standard split application of 80% K at planting with 20 % at head fill). The objectives were to assess the dunder impacts relative to potassium fertilisers on: cabbage yield, cabbage quality and uptake of the nutrients (N, K, Ca, Mg, Na). At maturity the cabbages were harvested and analysed for yield, quality and nutrient uptake. The cabbage yield in the raw and stable dunder and mineral K treatments were similar. Importantly, the raw or stable dunder has no negative effect on the shape and appearance of the cabbage. The timing of K application had no impact on cabbage yield or quality. The research shows that organic factory by-products may be substituted for normal mineral fertiliser. These by-products (in this case dunder) may be used as a single basal application to simplify their use in horticultural production systems.