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by Steven McCoy
Department of Agriculture Western Australia
April 2007
RIRDC Publication No 07/060 RIRDC Project No DAW-112A
Executive Summary
What This Project Is
About
This project demonstrates
the conversion of a conventional mango orchard to a certified organic system
in the Ord River Irrigation Area (ORIA) at Kununurra in the far north-east
of Western Australia.
Who This Project is Aimed
At
This project is aimed at
growers who are considering converting to organic production and those
who have already converted and considering different treatments.
Background
Mangoes were identified
as a prospective crop for conversion to organic production in the ORIA.
The comparative advantages that favour organic mango production in the
region are as follows:
Objectives
This project aimed to demonstrate
conversion of a conventional mango orchard to a certified organic system
in the ORIA at Kununurra in the far north-east of Western Australia.
Methods
A conversion demonstration
site was established on an existing conventional mango orchard.
Trees were 10 year old Kensington Pride (KP) variety, in good health on 8m by 4m spacing.
A nearby conventional orchard matched for soil type and tree age was selected for comparative assessment.
Three treatments were established: organic, organic plus compost and conventional.
Measurements were taken to assess soil conditions, plant tissue nutrition, yield and quality.
Indicative gross margins for the organic and conventional systems were calculated.
The transition to organic production was assisted by a prior shift in management from a chemical intensive approach towards a more biological approach with reduced synthetic chemical inputs. A relatively small area of the operation was converted to organic initially in order to gain knowledge, experience and confidence without significant commercial risk.
Choosing a relatively isolated site reduced the risk of contamination from adjacent land use and minimised the area needed for buffer zones between the two systems. Older trees were considered more suitable than younger trees because of their more extensive root system, less weed pressure, ability to cope with mild pest or disease pressure and possibly lower biennial bearing tendency.
An organic management plan was developed as the first step in clarifying the management changes required to comply with organic standards and certification procedures. Key management issues requiring attention related to the following:
Pack house operations
and post harvest treatment of fruit were also subject to compliance with
the organic standards.
Results
Results overall indicated
no major deterioration in soil conditions or tree health. Management of
nitrogen release from compost and mulch together with irrigation frequency
is considered important to avoid fruit quality problems.
Yield results for 2004 were similar to conventional production. For organic mangoes, production costs were slightly higher and gross margin returns were higher due to an average price premium of $2.00 per tray for the organic mangoes.
Implications
The current WA market for
organic mangoes is relatively small, although expanding rapidly.
Market development effort is required to lift demand volumes. Close management of supply volumes is important to maintain orderly market development.
Recommendations
The following future research
areas are recommended:
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