Micro-Irrigation Systems for Vineyards
Water Quality for Micro-Irrigation Systems
Water quality is probably the most serious concerns when considering micro-irrigation. In order to discharge very low flow rates, the diameter of the emitter orifices must be very small. This results in the emitters being blocked very easily by even the smallest contaminants in the water supply. Of particular concern are suspended solids, such as silt and sand, minerals that precipitate out of solution, such as iron or calcium, and algae that may grow in the water. A system with poor quality water simply will not function reliably enough to warrant the maintenance requirements needed to keep it in operation.
Water Quality Analysis
A water quality analysis can give the grower a “heads up” on potential trouble areas for the drip system. This test should be accomplished before the final design of the system to ensure that proper components are installed to address any problem areas.
Physical Properties
Suspended solids in the incoming water are the most common stress impinging upon the microirrigation system and the easiest to control. These particles can be either organic such as algae or inorganic such as sand.
Chemical Properties
The precipitation and deposition of calcium carbonate (lime scale) in vineyard micro-irrigation systems is one of the most common causes of system plugging and the associated loss of irrigation efficiency.
Calcium Carbonate (lime scale)
The precipitation and deposition of lime scale (calcium carbonate) in vineyard drip irrigation systems is one of the most common causes of system plugging and the associated loss of irrigation efficiency.
Iron and Manganese
Iron and manganese are another potential source of mineral deposits that can plug drippers. Iron and manganese precipitation can occur at low concentrations: iron at 0.3 ppm or greater and manganese at 0.15 ppm or greater.
Biological Causes of Emitter Clogging
A micro-irrigation system can provide a favorable environment for bacterial growth, resulting in slime buildup. This slime can combine with mineral particles in the water and form aggregates large enough to plug emitters. Certain bacteria can cause enough precipitation of manganese, sulfur, and iron compounds to cause emitter plugging. In addition, algae can be transported into the irrigation system from the water source and create conditions that may promote the formation of aggregates.
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