SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.
Issue link: http://read.dmtmag.com/i/775572
www.stma.org February 2017 | SportsTurf 21 water report. Both methods of reporting are useful. Total salts is a more direct approach while EC is indirect. Remember, 1ppm=1mg/L. TOTAL SALTS EC CLASSIFICATION MANAGEMENT <320 <500 Excellent None 320-960 500-1500 Good Little concern, especially with periodic rainfall 960-1920 1500-3000 Fair Leach salts from soil as needed 1920-3200 3000-5000 Poor Routinely leach; monitor soils 3200-3840 5000-6000 Very Poor Requires special attention; consult water specialist >3840 >6000 Unacceptable Do not use Table 2: Classification of irrigation water based on total salts (mg/L or ppm) and EC (µS/cm or µmhos/cm) (Adapted from Moss et al., 2016). The Sodium Adsorption Ratio is generally used to determine the ratio of sodium to calcium and magnesium in soils, which determines sodium status and permeability hazard. Although, this is a soil parameter, it can be used to classify irrigation water (Table 3) and is typically reported on irrigation reports. SAR CLASSIFICATION MANAGEMENT <1 Excellent None 1-2 Good Little concern; add pelletized gypsum periodically 2-4 Fair Aerify soil, sand topdress, apply pelletized gypsum, monitor soils 4-8 Poor Aerify soil, sand topdress, apply pelletized gypsum, monitor soils closely, leach regularly 8-15 Very Poor Requires special attention, consult water specialist >15 Unacceptable Do not use Table 3: Classification of irrigation water based on SAR (Adapted from Moss et al., 2016). TOTAL SALTS Together, total salts and SAR are used to help predict water infi ltration rates. Infi ltration refers to the soil's ability to allow water through; also referred to as soil permeability. Infi ltration rates can be improved by high total salts, but high salts may also reduce turfgrass health. Therefore, irrigation water with high salts can benefi t and damage turfgrass simultaneously (Fig. 1). Extremely pure water can lead to reduced infi ltration, even at low SAR. High total salts can help with infi ltration at medium to high SAR (15-20); high calcium and magnesium can counterbalance effects of high sodium. Figure 1: Total salts and SAR are used together to predict the effect of irrigation water on infiltration hazard (Adapted from Harivandi, 1999). EXAMPLE IRRIGATION WATER REPORTS Let's look at two example reports. Both reports will come from the Oklahoma State soil, water, and forage lab. These irrigation reports are broken down into categories that make it easy to see and know what to look for. These reports also include a paragraph that gives recommendations based on the reported values. This will not be the case for all labs, but is becoming more common. Example 1- Suitable Irrigation Water The pH of this water is in the upper part of our desired range. However, a pH of 8.4 will still allow for successful turfgrass growth without further remediation. A pH above 8.0 can cause higher bicarbonates, but in this case, since sodium is not an issue it should be suitable for turfgrass growth. The bicarbonate of this irrigation water is slightly above the threshold of 150 ppm. However, levels of carbonates and RSC are well within the low hazard category. The pH of the water Example 1- Suitable Irrigation Water Whatever your water source, it is important to test your irrigation water so you can successfully manage your field in the best way possible