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May 2011

How You Distribute Water = How You Distribute Salt


With summer around the corner, so too are high temperatures and with them the challenges of maintaining quality playing surfaces with limited (and often poor quality) water.

For many golf course managers, the month of May marks the beginning of a five-month stretch (May-Oct) of deficit irrigation. Deficit irrigation occurs whenever the irrigation rate is less than ET (evapotranspiration) plus a proper leaching fraction – in other words, the application of water below minimum turf-water requirements. This magnifies the negative impact of high-saline, reuse water because salts are unable to be adequately flushed from the root zone. During periods of deficit irrigation, how you distribute water = how you distribute salt.

Here’s where the importance of distribution uniformity and field-based uniformity comes into play. Distribution uniformity (DU) is a measure of how uniformly water is applied to the area being watered. Field-base uniformity (FBU) is how evenly that water is distributed within the soil profile. Low DU and low FBU equate to inefficient water distribution, which means that more water must be applied to meet the minimum watering requirement. The higher the DU and the FBU, the greater the efficiency, leading to healthy turf and water savings.

Many turf managers are focused on improving distribution uniformity (DU) by enhancing irrigation uniformity (adjusting sprinkler heads, tweaking irrigation schedules, installing new nozzles); however, improving field-based uniformity (FBU) through enhanced soil uniformity requires minimal investment to reap great rewards. If properly managed, improved soil uniformity can compensate for lack of irrigation uniformity.

Common treatment methods to improve field-based uniformity (FBU) include physical aeration, gypsum, acids and surfactants however these expensive inputs only provide a short-term fix. Conversely, FBU can be improved over the long-term by establishing a soil aggregate structure that resists compaction and allows for the movement of water into and within the soil profile.

HealthySoil® facilitates long-term improvements to aggregate soil structure with a series of mineral and biologically-diverse liquid applications. This creates micro-pores (or tiny spaces) in the soil that improve infiltration uniformity and provide enhanced retention of water / nutrients. The micro-pores are able to hold water / nutrients in the soil against gravity, readily available for plant uptake. Micro-pores contribute to the formation of water-stable aggregates that do not break down in the presence of water. This is of particular importance on the golf course where routine irrigation affects aggregate soil structure.

By improving the field-based uniformity (FBU) of fairways and greens, superintendents are able to:

  • Increase water efficiency to compensate for lack of irrigation uniformity and to magnify the benefits of retrofitted irrigation systems.
  • Implement effective leaching strategies to combat the negative impact of re-use water.
  • Reduce water use to lower costs.

Reduced water use leads to a cascade of benefits: less disease, less fertilizer, fewer salts, lower maintenance costs and higher-quality playing surfaces.

Understanding the complex soil ecosystem is a developing science. However, knowledge of soil science basics in combination with observations of natural, undisturbed soil systems will help superintendents to develop long-term solutions to today’s irrigation challenges.

Thomas Piatkowski is the President/CEO of HealthySoil.