Carob agroforestry industry: an assessment of its potential for the low-medium rainfall Murray Valley region

Abstract

This paper reports the key findings of a study examining the potential viability of a carob agroforestry industry in the low rainfall Murray Valley region. The carob fruit; typically produced on female and hermaphrodite trees older than 6 years, is valued for a range of products derived from the seed and pod. From the seeds, the endosperm is extracted for a galactomannan, which forms an edible gum (termed 'carob bean gum' or 'locust bean gum') and has become a valuable natural food additive. Carob powder, made by grinding the roasted pod, is used for the human food industry (with cocoa products and syrups). Ripe pods also have potential as a high energy stockfeed. The gum is used extensively in Australia as a thickening or binding agent, particularly for canned pet food products, with current imports valued at A$10 million/year. The current Australian demand for 'pet food' and 'technical' grade gum is estimated at 1200 t/year, with a further 200 t/year of the higher quality 'food' grade gum. Assuming a modern plant was built in Australia, the current Australian demand for carob gum could be met with about 2250 t of carob seed (seed value at $1600/t). This equates to 5405 ha of trees (at 104 trees/ha) with medium rainfall and low technology management (yielding 40 kg pods/tree); or 1080 ha of trees (at 208 trees/ha) with supplementary irrigation and fertilising (yielding 100 kg pods/tree). As such, carob could be a commercial tree crop for landholders in the Murray Valley region. This could be through the sale of seeds and pods, or as a supplement to livestock feeding. Economic analyses were undertaken to assess the relative viability of commercial returns when trees had access to adequate water through medium rainfall or irrigation, and growers had access to both the carob gum and powder markets. Commercial opportunities for carob growers within Australia vary considerably depending on establishment and maintenance costs, yields and access to markets.