An open hydroponics system aims to increase productivity by high frequency application of irrigation water and nutrients to the soil. Such a system is sometimes also called advanced fertigation.

Conventional involves adding a balanced amount of nutrient in the irrigation water, approximately once a month. This management system can be intensified by more sophisticated monitoring of water and nutrient use, and increasing the frequency of water and nutrient application. Systems where applications may be daily, or several times a day, are known as open hydroponics. A wide range of intensity of fertigation management has been adopted by irrigators.

Under open hydroponics the root-zone is kept restricted by increasing the number of drippers and using low application rates per tree. The root-zone volume may be only 0.5 m3 compared to 6-10 m3 for conventional fertigation. This concentrates the applied nutrients and potentially increases fertilizer use efficiency. Soil moisture content is maintained close to field capacity.

The benefits of open hydroponics may include some or all of the following:

earlier fruit production from establishing trees;

higher fruit production from mature trees;

a higher percentage of fruit suitable for the fresh fruit market (pack-out percentage).

Globally 46,500 ha of permanent horticulture are grown under open hydroponics. In Australia it has been estimated there are a total of 3,800 ha under citrus, avocados, almonds, table and wine grapes, mango, banana, blue berries, olives and stone fruits.

With funding from Horticulture Australia Ltd (HAL), and the former Land and Water Australia (LWA) through the National Program for Sustainable Irrigation (NPSI), the South Australian Research and Development Institute (SARDI) has carried out preliminary investigations. These have included an economic analysis, and some field observations of plantings under conventional fertigation and open hydroponics. The work has been done in collaboration the , and NSW Department of Primary Industries (NSWPDI) officers at Dareton Agricultural Research and Advisory Station.

In assessing any new technology it can be difficult to substantiate assumptions or claims made for the new systems being investigated. In the case of open hydroponics SARDI did not have the background data to rigorously test these assumptions, for example increased yield or a higher pack-out percentage. The assumptions used were based on field anecdotal evidence and research done outside Australia.

Other local anecdotal evidence suggests that with current lower juice prices, the advantage for open hydroponics may be almost entirely from increased pack-out percentage rather than any yield increase.