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Rural Industries Research & Development Corporation
Summary of full report
A report for the RIRDC/Land & Water
Australia/FWPRDC
Joint Venture Agroforestry Program
by Sarah Simpson and Peter Chudleigh, Agtrans Research
June 2001
RIRDC Publication No 01/08
RIRDC Project No AGT-7A
Wattle seed (Acacia spp.) has been used as a food source by Australian Aboriginal people for thousands of years. More recently, there has been a small but increasing demand for wattle seed as part of the commercial bush food market. Acacia spp. are often used in planting programs aimed at ameliorating land degradation. It has been suggested that the opportunity for broadscale wattle seed production and use of wattle seed in mainstream food production industries such as bread and biscuit making be investigated as a commercial output of future plantings of perennial species to combat rising watertables and dryland salinity
Currently, the market for wattle seed is almost solely as a bushfood. Wattle seed has been identified as one of the ten most commercially acceptable species of the bushfood industry (Graham and Hart 1998). Total product used by processors in 1995/96 was 6.0 tonnes at a wholesale price of approximately $30 to $35 a kilogram for clean, roasted seed, and $53 to $59 a kilogram for ground clean roasted seed (Graham and Hart 1998). A separate, more recent estimate is that the current demand for wattle seed is between 12 and 20 tonnes, with a farm-gate price of between $12 and $25 per kg of clean seed (Beal, pers comm, 2000). Variables that affect the price include the size of the consignment and the size and quality of the seed
The existing bush food market is expected to grow modestly over the next decade, particularly if export markets are developed. However, this specialty and novel food market will most probably never reach a scale where broadacre dryland production would be required
It may be possible to develop other markets for wattle seed, for example low glycaemic foods and in specialty flour markets for bread, biscuits, cakes and pastas. It is possible that only low proportions of wattle seed could be used in breads due to the absence of gluten. Further research is required into the baking characteristics of wattle seed in order to determine the maximum proportion of wattle seed that can be incorporated into breads
High usage markets such as starches, vegetable proteins or vegetable oils are possible, but would depend on the nutritional characteristics and food processing qualities of the seed, and on being able to be produced at very low cost in order to penetrate and compete in these markets
Four separate options for production systems for wattle seed have been identified _ plantation _ rotation (phase) cropping _ alley planting _ companion planting Currently, wattle seed supplying the bush foods market is harvested from natural stands. This wild harvesting is generally effected by hand and is very labour intensive. The development of an efficient and economic harvester for extensive wattle seed production is one of the key constraints to achieving a low production cost of seed and a large portion of the R&D required in regards to wattle seed production will need to be aimed at reducing the cost of harvesting
Three possible harvesting options have been identified:
1. ‘Butt-shaking’: An arm grabs the main stem (butt) of the tree and shakes, causing the seeds and pods to fall off. The Acacia seeds and pods are then collected in a metal tray that surrounds the tree
2. ‘Fingers’: A mechanical shaker which works by brushing plastic fingers through the outer foliage
This would be in the form of a stripper harvester that would have brushing fingers with keyholes to strip the pods. For this type of system to be successful however, the seed pods would need to be at the extremities of the bush and the bush would need to contain little heavy wood (maximum 15mm diameter)
3. Biomass harvest: Refers to harvesting by removing the entire above-ground biomass and then allowing coppicing. This would involve harvesting both seed and biomass once every four years or so by cutting back the tree to a stump and then allowing it to regenerate The major factors regarding the success and economic feasibility of harvesting Acacia seed relate to: _ the shape and silviculture properties of the species chosen _ the length of the available harvest window _ the harvesting method and its interaction within the production system with average yield per annum _ the potential for harvesting and utilising co-products There are over 1000 species of Acacia found in Australia, and caution must be exercised in selecting species suitable for cultivation for human consumption, and land restoration. One of the most important factors to consider is the toxicity of the seed of many species. Other important factors to consider in the selection of Acacia species suitable for broadscale production for human consumption include: _ Nutritional characteristics _ Adaptability of species to various climates and landscapes _ Growth characteristics (speed) _ Seed characteristics (size of seed crop, reliability and harvest window of the seed crop) _ Ease of propagation There is evidence to suggest that many species of Acacia are suitable for agroforestry systems for environmental purposes, and in fact there are many reported examples of Acacia being used for mine site rehabilitation and other land regeneration plantings. Little or no research has been done at this stage into the rate of water use of Acacia species, and their likely success in reducing the level of the water table
Olsen (pers comm, 2000) states that the level of water use of Acacias will be dependent on many factors, including the growth rate of the plant, the plant spacing, frequency of harvest, amount of foliage growth between harvests, and a range of environmental factors (eg. rainfall, soil type, depth of unsaturated zone, availability of fresh groundwater)
Investment analyses were carried out for each of the three separate harvesting scenarios identified
Specific assumptions used are associated with a high degree of uncertainty. Results are presented below
Base Results for Benefit-Cost Analysis
(for 1 hectare, over 12 years, at a 10% discount rate)
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The results show that production under Scenario 1 (harvest by ‘butt-shaking’), is not economically viable unless the cost of harvesting can be reduced to $1070 per hectare, or if the yield and/or farm-gate price can be significantly increased. It may only be appropriate for this harvesting method to be used to service the bushfood or other niche industries, where a premium price for wattle seed can be attained and where other harvesting methods have not been developed
Scenarios 2 (harvest by ‘fingers’) and 3 (biomass harvest) both show promise of being economically viable, and at appropriate yields, able to be remain economically viable at a farm-gate price of less than $1/kg. Other analyses in the report suggest that wattle seed production could compete with wheat financially, given the assumptions made
From sensitivity analyses conducted it is evident that there are three key drivers of the economic viability of wattle seed production
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