**2. Materials and methods**

#### **2.1. Study location**

and

**1. Introduction**

78 Arid Environments and Sustainability

P2 O4

effects on soil and plants.

irrigation resources such as desalinized seawater [11].

The increase of the world's population and the decrease of freshwater resources have led to increased use of alternate water resources. In contrast, as the population increases, wastewater production increases. In many arid and semiarid areas in USA, Australia, and Israel, using freshwater for turfgrass and landscape irrigation has become rare. Consequently, using treated wastewater (effluent water) for irrigation has become a common practice to alleviate freshwater shortage. In addition to the growing concerns of the future water supply, the more stringent wastewater discharge standards make use of effluent water increasingly attractive. Golf courses are the leading urban landscape users of effluent water. A survey conducted by the National Golf Foundation (NGF) reported that approximately 13% of golf courses in the US use effluent water for irrigation, with 34% of golf courses in the Southwest US doing so [1].

In Colorado, approximately 25% of golf courses are using effluent water for irrigation.

Effluent water is any water after residential and sometimes industrial use that undergoes significant treatment at a sewage treatment plant, to meet standards set by federal or state water laws and regulations. This water is usually suitable for various reuse purposes including irrigation. During treatments, suspended solids are removed, pathogens are disinfected, and partial to substantial reduction in nutrient concentrations occurs, depending on treatment stage [2, 3]. Currently, effluent water used for turf and landscape irrigation must be disinfected [4]. However, using effluent water has some disadvantages. Public health is the first concern due to the pathogens it may contain, but that is less of a concern if used for nonedible plants. Effluent water may contain different levels of dissolved solids, ions, nutrients (NO3

), and other elements. Increases in soil salinity and sodium are potential problems associated with using effluent water irrigation. Salinity has harmful effects on nonhalophyte plant growth and development as well as making soil water less available for the plants. Increased sodium level (sodicity) in the soil leads to disaggregation of soil to its components and damages the soil structure. In addition, researchers suggest that using effluent water for irrigation may affect soil chemistry over time [5–9]. Accordingly, the use of effluent water for irrigation requires monitoring and the use of management practices to minimize any potential adverse

On the other hand, using effluent water for irrigation has some advantages. Effluent water contains some nutrients that can be used by plants. Nitrogen (N) and phosphorus (P) as well as some small amounts of micronutrients are found in effluent water. Studies have showed that plant yields increased by using effluent water when compared to freshwater irrigation [10]. This increase is due to the nutrient concentrations such as N and P in effluent water and their effect on plant growth [10]. High-quality effluent water has become available for golf course irrigation, and it decreases the fertilizer cost because of nutrient availability in the water [4]. Also, using effluent water is less expensive when compared to other alternative

Many studies have been published regarding the effect of using effluent water on soils in urban landscapes. However, no research is available regarding the impacts of effluent water irrigation on sand-based root zones on golf course putting greens and sports fields. Research The study was conducted at Heritage Golf Course in Westminster, Colorado, which is located north of metro Denver (39° 53′ 59.34″ N 105° 07′ 00.04″). The course started to use effluent water for irrigation in 2000. Nine out of 18 (1, 3, 5, 7, 9, 11, 13, 15, 17) greens were selected for soil sample collection. Soil samples (0–10 cm below soil surface) were collected in September of 1999, 2003, and 2009.

Soil samples were analyzed for soil pH, extractable salt content (Ca, Mg, K, Na, Fe, Mn, Cu, Zn, P, and B), base saturation percent of Ca, Mg, K, and Na, soil organic matter (SOM), and cation exchange capacity (CEC) by Brookside Laboratories, Inc. (New Knoxville, OH). Soil pH was analyzed using 1:1 H<sup>2</sup> O procedure; 1:1 is the most common ratio used for soil-water pH. It is performed by mixing an equal volume of soil and deionized water. Soil samples were extracted using the Mehlich III extract (0.015 M NH4 F + 0.20 M CH3 COOH + 0.25 M NH<sup>4</sup> NO3 + 0.013 M HNO3 + 0.0005 M EDTA chelating agent) to determine Ca, Mg, K, Na, Fe, Mn, Cu, Zn, B, and P by inductively coupled plasma-emission spectrophotometry instrumentation. Mehlich III is a procedure widely used for extraction of plant available macro- and micro-nutrients in soils that have an acidic or neutral pH, by using a dilute acid-fluoride-EDTA solution with pH 2.5 extracted [14]. Mehlich III extracted Ca, Mg, K, and Na plus soil buffer pH data are used to calculate CEC. Base saturation percent of Ca, Mg, K, and Na was calculated by dividing the extracted Ca, Mg, K, and Na by the calculated CEC, respectively. Base saturation percent of Na is considered the exchangeable sodium percentage (ESP). Soil organic matter was determined by reaction with Cr<sup>2</sup> O7 2− and sulfuric acid. The remaining unreacted Cr2 O7 2− is titrated with FeSO4 using ortho-phenanthroline as an indicator, and oxidizable organic matter was calculated by the difference in Cr<sup>2</sup> O7 2− before and after the reaction [15]. Estimated N release is calculated to determine the potential amount of N released annually by SOM decomposition.

**Water quality parameters**

NH<sup>4</sup>

NO3

(*P* < 0.05).

pH 7.4

–N 0.8 mg L−1

Long-Term Effects of Effluent Water Irrigation on Soil Chemical Properties of Sand-Based...

http://dx.doi.org/10.5772/intechopen.72227

81

–N 2.9 mg L−1 Total P 0.6 mg L−1 Total dissolved salts 638

Conductivity 0.99 dS m−1 Sodium absorption ratio (SAR) 3.05 Adjusted SAR 5.74 Na 101 mg L−1 Cl 120 mg L−1 Bicarbonate 125 mg L−1 Ca 67 mg L−1 Mg 11.8 mg L−1 Sulfate 182 mg L−1 B 0.21 mg L−1 Fe 0.31 mg L−1 K 16.9 mg L−1 Total suspended solid (TSS) 9.1 mg L−1

**Table 1.** Effluent water quality used in Heritage Golf Course (season average).

**Figure 1.** Effect of using effluent water irrigation on soil pH. Different letters indicate significant differences using LSD

#### **2.2. Data analysis**

Data were analyzed by analysis of variance (ANOVA) [16] to test the effect of irrigation with effluent water on individual soil chemical properties. Comparisons between years were examined, and means were separated by LSD at 0.95 level of confidence. Regression analysis was used to examine the changes in individual soil parameters over time after the use of effluent water for irrigation.
