Fertigation Systems for Vineyards

Fertigation is the application of dissolved fertilizers through an irrigation system to the vineyard. Most commonly this is done through a drip irrigation system but it can also be done with microsprinklers. Using a fertigation system, a wine grape grower can apply fertilizer anytime, and place it where the grapevine roots are most numerous and active. In addition to greater flexibility in application timing and placement, fertigation increases the rate of nutrient uptake and predictability of vine response to fertilization compared to band and broadcast applications. Effective fertigation requires knowledge of certain grapevine characteristics such as optimum daily nutrient consumption rate and root distribution in the soil. Nutrient characteristics such as solubility and mobility are important and irrigation water quality factors such as pH, mineral content, salinity, and nutrient solubility must be considered. The macronutrients nitrogen, potassium, phosphorus, and magnesium are the most common nutrients applied by fertigation, but micronutrients such as boron, zinc, iron, calcium manganese, and copper can also be applied through the irrigation system. In addition, to fertilizers other chemicals can be injected through the irrigation system, including chlorine, acid, herbicides, nematicides, and fungicides.
For more information go to the source of the above – Wine Grape Growing

Fertigation

System Design
There are four injection methods which can be used and the one you choose will primarily depend on the type of irrigation system used.
For continuous moving irrigation systems (centre pivot / lateral move), venturi injectors and positive displacement (pressure) pumps are best. For non-mobile systems (drip / micro / overhead spray) these injections systems can also be used, as well as suction injection and pressure differential.
Venturi injection
Venturi injectors come in several sizes and can be operated under different pressure conditions. Venturi injectors are only usable on closed pipe systems as they are set up in a shunt pipeline parallel to the main irrigation pipeline close to the pivot or lateral structure.
Requiring at least a 20 per cent pressure differential to work properly, irrigation water from the main pump is passed through the venturi unit, creating a pressure differential between the water bypassing the unit and the fertiliser solution in the tank. This pressure differential causes the solution to be drawn up into the mainline. The gate valves and flow rate control the rate of the fertiliser solution applied. The venturi draws all the fertiliser until the tank is empty. Venturi injectors do not require external power to operate but some units utilise a small booster pump in the shunt pipeline to produce a differential pressure. Injection rates of 10 to 20,000 litres per hour can be achieved.
The advantages include:
• no moving parts – typically manufactured from plastic
• requires little maintenance
• gate valves control fertiliser injection rates with some accuracy
• large volumes can be mixed and stored on site
• reduces OH&S issues in dealing with fertiliser.
Disadvantages include:
• requires a closed pipe system
• requires pressure loss in main irrigation line (can be up to 33 per cent)
• automation is difficult but not impossible.

The full article is no longer available but was originally sourced at Growcom.com.au

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Wassertec are agents for Mazzei Injectors, which are made in the USA. Mazzei venturi injectors are engineered from highly chemically resistant Kynar (PVDF) and are available in sizes ranging from ½ inch to 12 inch pipe diameter. We keep stock of models in the ½ inch to 3 inch range. Other sizes are available on request.

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