Open Hydroponics is an open field horticulture production system that is based on artificial media hydroponic crop production principles. Open Hydroponics incorporates certain practices to achieve a hydroponic type situation. These practices included:

• Using drip irrigation with a restricted root zone to reduce the influence of the soil as a media to store nutrients and water. The soil is only considered as a media to provide structural integrity for the tree and as a container for the roots and water nutrient solution. The cation exchange capacity of the soil has a reduced influence.
• Moisture levels and maintained near to field capacity. This maintains an ample water nutrient solution around the roots. The secondary benefit is that the tree never experience is water stress.
• Complete and balance nutrient solutions (macro and micro nutrients) are applied with every irrigation. Since the soil is no longer a nutrient storage source, nutrition must be applied daily with every irrigation.

Commercial orchards using Open Hydroponics are reporting increased production levels. The special feature of Open Hydroponics claimed by users is the ability to have greater control of nutrient concentrations in the soil solution and subsequently a higher degree of nutritional control of the tree. With the use of restricted root zones, high soil solution nutrient concentrations can be achieved at specific physiological stages which can theoretically increase the uptake of specific nutrients. Higher soil nutrient concentrations are also claimed to stimulate more root growth and therefore contribute in increasing the bearing capacity of the tree.

There are a number of practical interpretations of Open Hydroponics are around the world, and two are currently operating in Australia. Open Hydroponics is an opportunity to possibly increase production, productivity levels, and water use efficiency. Horticultural industries, water providers and regulators need to understand this technology to properly plan for possible increased adoption of this technology.

Stage 1- July 2004 - March 2005

• Conduct a literature review to investigate the principles and practices of Open Hydroponics.
• Prepare a case study of typical Open Hydroponics to be used in assessment studies.
• Conduct a salt/nutrient water balance based on case studies (eg. Soil pH, nutrient leeching, efficient and inefficient irrigation practices, rainfall etc).
• Conduct a water supply infrastructure assessment to assess the ability of water service providers to meet irrigation demands of Open Hydroponics.
• Conduct an ecological at risk assessment to assess the possible risks and hazards associated with Open Hydroponics ( Linked to NPSI Ecological Risk Assessment project UMO45)
• Conduct a workshop with appropriate industry officers to discuss the results of stage one investigations. Assess if Open Hydroponics is a beneficial production system to promote to the Australian horticultural industry. If assessed as beneficial then provide feedback to continue with stage two of the project.
• Advise horticultural industry, water service providers and regulators of the project findings and results.

4 years

• Introduction to Open Hydroponics (pdf 70Kb)
• Adopting Open Hydroponics: Factors to Consider (pdf 70Kb)
• Open Hydroponics: Risks and Opportunities, Stage 1 Project Findings Overview (pdf 70Kb)
• Open Hydroponics: Risks and Opportunities, Stage 1: General Principles and Literature review (pdf 836Kb)
• Open Hydroponics: Risks and Opportunities, Stage 1: Water Nutrient and Salt Balance Report (pdf 535Kb)
• Open Hydroponics: Risks and Opportunities, Stage 1: Water Supply Impact Assessment Report (228Kb)
• Open Hydroponics: Risks and Opportunities, Stage 1: Ecological Risk Assessment Report (301Kb)
• Open Hydroponics: Risks and Opportunities, Stage 1: Final Report (pdf 190Kb)
• Open Hydroponics: Risks and Opportunities, Stage 1: Workshop Report (pdf 2Mb)