Chapter 15

Water Quality for Irrigating Vineyards

Irrigation Water Testing and Analysis

The quality and content of the irrigation water can greatly affect the success of your vineyard. Testing the irrigation water is important for assessing the suitability of the water source for irrigation. All irrigation water sources should be tested for pH, alkalinity, conductivity, hardness, chloride, and sodium at a minimum since these are common issues with water supplies. A more thorough test is ideal and should also include total dissolved solids, boron, calcium, magnesium, sodium adsorption ratio (SAR), nitratenitrogen, ammonium-nitrogen, phosphorus, potassium, sulfur, iron, manganese, copper, molybdenum, and zinc (See Table 15.1). Water test results should be considered in combination with soil test results for establishing a baseline.

Analysis Units

Laboratories will report values in different units depending on their protocol. Thus, it is often necessary to convert from one unit of measurement to another. Parts per million (ppm), milligrams per liter (mg/L), and milligrams per kilogram (mg/kg) are numerically equivalent and interchangeable. If necessary, use Appendix C, Water Quality Conversion Table, to convert to other units of measure. Another unit which is often reported, milliequivalent weight (mg/meq), is a unit used to compare concentrations of ions with different atomic weights and charges.

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