Long Term Effects of Effluent Water Irrigation on Soil Nitrate and Phosphorus Profiles under Turfgrass
This study seeks to determine whether the use of effluent
water over time has an effect on the nitrate and phosphorus content of
the soil. We took soil samples from six golf courses that have been irrigating
with effluent water for various periods of time. On each golf course soil
cores were sampled from three different fairways to a depth of one meter
and then subdivided into 20 cm increments. Regression analysis was conducted
on the averaged values from each golf course to evaluate the relationship
between the length of time of effluent usage and soil nitrate or phosphorus
content. Results indicate that though there is no significant correlation
between the number of years of irrigating with effluent water and the
amount of nitrate in the soil, there is a strong correlation between the
number of years of effluent irrigation and the amount of phosphorus at
the surface 0-20 cm of the soil. The study strongly advocated that proper
management of wastewater irrigation and periodic monitoring of soil and
groundwater parameters are required to ensure successful, safe, long term
Water shortages are becoming increasingly common in the arid and semi
arid areas of the USA. Increased use of reclaimed wastewater (RWW), i.e.,
recycled water, is viewed as one of the approaches to maximize the existing
water resource and stretch current urban water supplies (US EPA, 2004).
Wastewaters often contain significant concentrations of organic and inorganic
nutrients for example nitrogen and phosphate. There is potential for these
nutrients present in recycled water to be used as a fertilizer source
when the water is recycled as an irrigation source. Golf courses and urban
landscapes are by far the leading users of recycled wastewater; intensively
managed turfgrasses utilize a significant amount of water and nutrients
in the wastewater. However, there are concerns that the contaminants and
excess nutrients left in the water after treatment can make their way
into the ground or surface water supplies. Specific concerns are that
nitrates will move through the soil structure and cause ground water contamination
and that phosphorus will run off into surface waters, promoting algal
blooms and eutrophication.
Research done in southern US has indicated that dense, well-managed turfgrass
areas are among the best bio-filtration systems available for removal
of excess nutrients (Hayes et al., 1990). A properly managed golf
course will have little problem with nitrogen leaching down into groundwater,
or phosphorus running off to surface waters if best management practices
are utilized, including fertilizing in several smaller applications instead
of one large one and watering shortly after fertilizer application (Higby
and Bell, 1999). The concern is that with the water containing the nutrients,
there may be a conflict with how much nutrients vs. how much water the
turf needs for maintaining desired color and growth. In applying enough
water to maintain desirable turfgrass quality, more nutrients than needed
may be applied, thus exceeding the turf`s agronomic rate, or rate of nutrient
use. Compounding the problem, during the summer months when the nutrient
requirements of the cool season turfgrass are lower, more water is being
applied to maintain the green turf system.
To date, the contribution of water reuse to water conservation varies
by location. Water reuse satisfied 25% of the water demand in Israel,
for example, where 66% of total treated sewage is reused (Avnimelech,
1993). Water reuse is expected to reach 10 to 13% of water demand in the
next few years in Australia and California (Lazarova and Asano, 2005).
Throughout the US, large volumes of municipal recycled water is being
used to irrigate golf courses, community parks, cemeteries, athletic fields,
schoolyards, roadsides, street medians, industrial and residential landscapes
and other urban landscape sites (Golf Course Superintendents Association
of America, 2003; US EPA, 2004; Qian, 2004; Qian and Mecham, 2005; Devitt
et al., 2004, 2005). Mohammad and Mazaherh (2003) focused on change
in soil fertility parameters in response to RWW irrigation of forage crops.
The average characteristics of wastewater and potable water parameters
(mg kg-1) were: PO4 (49 and 0.03), NH4
(118 and not determine-ND), NO3 (29 and 59), Fe (0.14 and ND),
Mn (0.07 and ND), Zn (0.03 and ND), Cd (0.04 and ND), Cr (0.01 and ND),
Pb (0.02 and ND). In first and second season application of wastewater
to crops was 675 and 765 mm, respectively, while application of potable
water 540 and 615 mm, respectively. The study revealed that wastewater
significantly increased the soil P (9.9 and 9.2 mg kg-1) compared
to potable water increased soil P (4.3 and 3.5 mg kg-1) at
0-30 and 30-60 cm soil depth, respectively. Also, wastewater resulted
in significant increased in soil K (653 mg kg-1) compared to
potable water increased soil K (502 mg kg-1) only at depth
of 30-60 cm, while these was no significant change in soil K at 0-30 cm
depth. The study concluded that secondary sewage wastewater improved the
soil fertility status.
Similarly results of increase in soil fertility were found by Mancino
and Papper (1992), secondary sewage effluent containing of phosphorous
27 mg L-1, significant increased the soil P form approximate
level of 17 mg kg-1 to approximate level of 32 mg kg-1,
while with potable water there was reduction soil P form approximate level
of 17 mg kg-1 to approximate level of 7 mg kg-1
in 3.3 years of irrigation to bremudagrass turf.
Hayes et al. (1990) studied the effect of secondary sewage effluent
on the sandy soil ground under turfgrass cover. And found that after 16
mo of effluent irrigation compared to potable water, effluent was found
to increased the soil NO3-N by 7.8 mg kg-1, P by
31.7 mg kg-1, K by 134 mg kg-1 and Na by 6.0 mmol
L-1, while there was decrease in the concentration of soil
Land application of effluent, as opposed to direct discharge to water
ways, is becoming widespread in New Zealand as regulatory authorities
move to protect and enhance water quality and meet Maori spiritual and
cultural values (Cameron et al., 1997; Anonymous, 1999; Wellington
Regional Council, 1999a). This method was used to treat effluent from
townships, meat works, dairy factories and dairy farms (Schipper and Lloyd-Jones,
1999; Selvarajah, 1996; Cameron et al., 1997; Tomer et al.,
1997; Sparling et al., 2001). A major concern in New Zealand at
present is the potential impact of farm dairy effluent (FDE) on the environment
(Environment Waikato, 1998; Wellington Regional Council, 1999b). Hawke
and Summers (2003) reported that the concentrations of total carbon and
total Kjeldahl nitrogen were generally low at all depths, the application
of effluent caused a significant increase in their concentrations in the
upper 10 cm of the profile. Similarly, the concentration of exchangeable
cations increased in the upper 10 cm of the profile. The soil showed very
low phosphorus retention; however effluent application increased both
the total and Olsen phosphorus to 40 cm depth. Most of the changes in
soil properties led us to believe that current application rates and pasture
production could be maintained and that FDE application improved the soil`s
long-term fertility or soil quality, especially in the upper 10 cm of
the profile. However, there was no evidence to suggest that current application
rates are sustainable in terms of other environmental effects (e.g., nitrate
leaching). Despite the increasing pressure on farmers to move to land-based
application of FDE to decrease impact of effluent on waterways and the
considerable research on the impacts of FDE application, the long-term
effects on soil properties are not fully known (Degens et al.,
2000). Rusan et al. (2007) concluded that long term wastewater
irrigation increased salts, organic matter and plant nutrients in the
soil. Also, wastewater irrigation had no significant effect on soil heavy
metals (Pb and Cd) regardless of duration of wastewater irrigation.
The main objective of land-based effluent application is to utilize the
chemical, physical and biological properties of the soil/plant system
to assimilate the waste components without adversely affecting soil quality
or releasing potential contaminants to water bodies (including the groundwater)
or the atmosphere; hence, the area of land and the soil physical, chemical
and biological conditions are important in order to achieve this objective
(Cameron et al., 1997; Sparling et al., 2001). The management
of nitrogen and phosphorus to prevent possible groundwater or surface
water contamination is a key issue for the long-term sustainable use of
effluent-irrigated land (Falkiner and Polglase, 1997). To avoid adverse
effects on the environment and human health, rules have been set by some
regional councils to restrict the rate of Farm Dairy Effluent (FDE) application;
however, such rules fail to take into account the heterogeneous nature
of soil (Silva et al., 1999).
There are some problems associated with the long-term use of effluent
water for irrigation such as change in the soil`s physical and chemical
properties. The majority of the studies on a turf system`s ability to
uptake nutrients have been done on young plots (<10 years). We are
interested in examining the long-term effects of effluent water irrigation
on the nitrate and phosphorus concentrations in the soil. The objectives
of this study were: 1): to determine soil NO3-N and P concentrations
at various depths from different golf courses that vary in the time of
effluent water usage in the Denver, CO area and 2): to determine the significance
of the number of years of effluent water irrigation on nitrate and phosphorus
amounts in the soil.
MATERIALS AND METHODS
Sampling and site description: Golf courses for the study were
selected on the basis of the number of years of effluent water irrigation.
Six golf courses ranging from one to 33 years of effluent water use were
sampled. Three fairways were sampled at each course and a total of three
soil cores were taken at each fairway. Fairways were sampled using a handheld
boring tool, each core was taken to a depth of one-meter and each core
separated into 20 cm increments, for a total of five samples per core.
The samples from each fairway were combined for a total of 15 samples
taken per golf course.
At each golf course three fairways were selected based on their physical
characteristics. The soil samples were taken from one fairway with good
drainage and the other two with fair to poor drainage at each course.
By averaging the data between the three fairways, a reasonable overview
of the soil profiles of each course was presented.
The Golf Course No. 1 has been using effluent water irrigation for one
year. Fairway soil texture is clay. The turfgrass is fertilized at a rate
of 73.5 kg N ha-1 year-1. The total water applied
is approximately 647.7 mm of water per year. The Golf Course No. 2 has
been using effluent water irrigation for 3 years. Fairways soil texture
is clay loam. The turfgrass is fertilized at a rate of 73.5 kg N ha-1
year-1. Fairways are irrigated with 254-508 mm of water per
year. The Golf Course No. 3 has been using effluent water irrigation for
thirteen years. Fairway soil texture is clay. The turfgrass is fertilized
at a rate of 196 kg N ha-1 year-1. The total irrigation
water applied is approximately 508-762 mm of water per year. The Golf
Course No. 4 has been using effluent water irrigation for thirteen years.
Fairway soil texture is clay. The turfgrass is fertilized at a rate of
98 kg N ha-1 year-1. The irrigation water applied
is approximately 610 mm of water per year. The Golf Course No. 5 has been
using effluent water irrigation for seventeen years. Fairway soil texture
is sandy clay loam. The turfgrass is fertilized at a rate of 73.5 kg N
|| Golf courses selected for the study
The total irrigation water applied is around 508-762 mm of water per
year. The Golf Course No. 6 has been using effluent water irrigation for
thirty-three years. Fairway soil texture is clay. The turfgrass is fertilized
at a rate of 98 kg N ha-1 year-1. The total irrigation
water applied ranged between 508-762 mm of water per year (Table
Determination of soil nitrate and phosphorus content: Extractable
soil phosphorus data was collected using the AB-DTPA Soltanpour and Schwab
method. Phosphorus content is determined spectrophotometrically at 882
nm at an acidity of 0.18 M H2SO4 (Rodriguez et
al., 1994) by reacting with ammonium molybdate using ascorbic acid
as a reductant in the presence of antimony (Murphy and Riley, 1962). Soil
nitrate was determined by using a two molar KCl extract and running it
through a flow injector (Spark, 1996).
Statistical analysis: Statistical analysis was performed using
PC-SAS version 8.0 to determine differences among sites, years and depths
of soil nitrate and phosphorus. Regression analysis was conducted to evaluate
the relationship between the length of time of effluent water usage and
soil nitrate or phosphorus content.
RESULTS AND DISCUSSION
In general, NO3 contents decreased significantly with soil depth,
suggesting that the turfgrass root system was very effective for nitrate uptake
(Fig. 1). Exceptions were observed at the golf course No.
6 tenth fairway and the golf course No. 3 eleventh fairway, where higher nitrate
content was found at the 20-40 cm depth. At both locations, soils are poorly
drained and anaerobic conditions were identified approximately 40-50 cm below
The average value of the three fairways from each course was used in
order to compare golf courses by the number of years of effluent use (Table
2). Although, there were significant differences between the various
courses at each depth, but there was no clear indication that the number
of years of effluent water irrigation affected the nitrate level in the
soil (r = 0.01, p = 0.7).
|| Soil nitrate concentrations from six sites at 20 cm
depth increments to one meter deep
|| Mean concentration of soil NO3-N from 6
|Sites are arranged by years of effluent use, youngest
Since, there was no statistical correlation
between the number of years of effluent use and the nitrate levels in
the soil, it was clear that the nitrate levels beyond the turfgrass root
zone are low (<2 mg kg-1) and were below the EPA standard
for potable water quality (10 mg kg-1). This indicates that
nitrate contamination of groundwater should not be a concern when using
effluent water for the irrigation of turf systems.
Statistical analysis was performed to determine differences among sites,
years and depths of soil phosphorus. Data from the three sampled fairways
were averaged together to show the length of effluent use on extractable
soil P content (Table 3).
|| Mean contents of soil P from six sites
|Sites are arranged by years of effluent use, youngest
Phosphorus levels were consistently
higher at the 0-20 cm depth than the deeper depths and there is a clear
trend showing that the number of years of effluent use affected the amount
of phosphorus at the soil surface depths (r = 0.69, p = 0.002).
The golf course No. 1 did not appear to follow the general trend as there
was more phosphorus in the soil than one might expect having used effluent
irrigation for such a short time. However, although this golf course has
only been using effluent water irrigation for one year, it is an older
golf course than the golf course No. 2, which could explain this anomaly.
|| Soil phosphorus concentrations from six sites at 20
cm depth increments to 1 m deep
In addition, the golf course No. 5 had higher phosphorus concentrations
at lower depths than the courses that have used effluent irrigation for
a greater number of years. While phosphorus is often considered immobile,
the coarse (sandy) soil texture of the golf course No. 5 allowed increased
percolation and therefore increased movement of phosphorus through the
soil structure (Fig. 2).
The concentration of phosphorus in the upper levels of soil in these
courses, particularly those that have been using effluent water for many
years, exceeded the very high limit according to the AB-DTBA test that
was used to measure phosphorus concentrations (James, 2000). Still, the
water features of the golf courses did not display the discoloration or
odor associated with the algal blooms caused by excess phosphorus runoff,
indicating that the turf is effective at preventing phosphorus runoff.
Any change in land use that would require removing the turf will also
require some kind of remediation to prevent excessive amounts of phosphorus
from entering the watershed. Similar results were reported by Hawke and
Summers (2003) who stated that the effluent application increased both
total and Olsen phosphorus to 40 cm soil depth.
There was no correlation between the number of years of effluent irrigation
and the amount of nitrate in the soil. A strong correlation was observed
between the number of years of effluent irrigation and the amount of phosphorus
in the soil. The phosphorus levels in the soil resulting from effluent
water use were very high and tend to remain in the upper levels of the
soil structure. The study strongly advocated that proper management of
wastewater irrigation and periodic monitoring of soil and groundwater
parameters are required to ensure successful, safe, long term wastewater
Resource Management Act-Practice and performance: A case study of farm dairy effluent management. Ministry for the Environment, Wellington.
Avnimelech, Y., 1993.
Irrigation with sewage effluents: The Israeli experience. Environ. Sci. Technol., 27: 1278-1281.CrossRef |
Cameron, K.C., H.J. Di and R.G. McLaren, 1997.
Is soil an appropriate dumping ground for our wastes?. Aust. J. Soil Res., 35: 995-1036.CrossRef |
Degens, B.P., L.A. Schipper, J.J. Claydon, J.M. Russell and G.W. Yeates, 2000.
Irrigation of an allophonic soil with dairy factory effluent for 22 years: Responses of nutrient storage and soil biota. Aust. J. Soil Res., 38: 25-35.Direct Link |
Devitt, D.A., R.L. Morris, D. Kopec and M. Henry, 2004.
Golf course superintendents attitudes and perceptions toward using reuse water for irrigation in the Southwestern United State. Horttechnology, 14: 1-7.
Devitt, D.A., R.L. Morris, M. Baghzouz and M. Lockett, 2005.
Water quality changes in golf course irrigation ponds transitioning to reuse water. HortScience, 40: 2151-2156.Direct Link |
Environment Waikato, 1998.
Waikato State of the Environment Report 1998. Hamilton, Environment Waikato, pp: 244.
Falkiner, R.A. and P.J. Polglase, 1997.
Transport of phosphorus through soil in an effluent-irrigated tree plantation. Aust. J. Soil Res., 35: 385-397.
Golf Course Superintendents Association of America (GCSAA), 2003.
Water Woes: A New Solution for Golf Courses. http://www.gcsaa.org/news/releases/2003/june/effluent.asp.
Hawke, R.M. and S.A. Summers, 2003.
Land application of farm dairy effluent: Results from a case study, Wairarapa. N. Z. J. Agric. Res., 46: 339-346.Direct Link |
Hayes, A.R., C.F. Mancino, W.Y. Forden, D.M. Kopec and I.L. Pepper, 1990.
Irrigation of turfgrass with secondary sewage effluent: II. Turf quality. Agron. J., 82: 943-946.CrossRef | Direct Link |
Higby, J.R. and P.F. Bell, 1999.
Low soil nitrate levels from golf course fairways related to organic matter sink for nitrogen. Commun. Soil Sci. Plant Anal., 30: 573-588.
James, S., 2000.
Phosphorus levels in colorado soils. Agron. News, 20: 7-7.
Lazarova, V. and T. Asano, 2005.
Challenges of Sustainable Irrigation with Recycled Water. In: Water Reuse for Irrigation. Agriculture, Landscapes and Turf Grass, Lazarova, V. and A. Bahri (Eds.). CRC Press. London, New York, pp: 1-30
Mancino, C.F. and I.L. Pepper, 1992.
Irrigation of turfgrass with secondary sewage effluent: Soil quality. Agron, J., 84: 650-654.Direct Link |
Mohammad M.J. and N. Mazahreh, 2003.
Changes in soil fertility parameters in response to irrigation of forage crops with secondary treated wastewater. Commun. Soil Sci. Plant Anal., 34: 1281-1294.Direct Link |
Murphy, J. and J.P. Riley, 1962.
A modified single solution method for the determination of phosphate in natural waters. Anal. Chim. Acta, 27: 31-36.CrossRef | Direct Link |
Qian, Y.L., 2004.
Urban landscape irrigation with recycled wastewater: Preliminary findings. Colorado Water, 21: 7-11.
Qian, Y.L. and B. Mecham, 2005.
Long-term effects of recycled wastewater irrigation on soil chemical properties on golf course fairways. Agron. J., 97: 717-721.CrossRef |
Rodriguez, J.B., J.R. Self and P.N. Soltanpour, 1994.
Optimal conditions for phosphorus analysis by the ascorbic acid-molybdenum blue method. Soil Sci. Soc. Am. J., 58: 866-870.
Rusan, M.J.M., S. Hinnawi and L. Rousan, 2007.
Long term effect of wastewater irrigation of forage crops on soil and plant quality parameters. Desalination, 215: 143-152.CrossRef | Direct Link |
Williamson, J.C., G.P. Sparling, G.N. Magesan, L.A. Schipper and A.R. Lloyd-Jones, 1999.
Hydraulic conductivity in soils irrigated with wastewaters of differing strengths: Field and laboratory studies. Aust. J. Soil Res., 37: 391-402.CrossRef |
Selvarajah, N., 1996.
Determination of Sustainable Nitrogen Loading Rates for Land Treatment Systems without Adequate Soil and Groundwater Information: Dairy Farm Effluent Application onto Grazed Pasture in the Waikato Region. In: Recent Developments in Understanding Chemical Movements in Soil, Currie, L.D. and P. Loganathan (Eds.). Massey University, New Zealand. Fertiliser and Lime Research Centre, Occasional Report No. 7, pp: 160-185
Silva, R.G., K.C. Cameron, H.J. Di and T. Hendry, 1999.
A lysimeter study of the impact of cow urine and nitrogen fertilizer on nitrate leaching. Aust. J. Soil Res., 37: 357-369.
Spark, D.L., 1996.
Methods of Soil Analysis. Part 3. Chemical Methods. Soil Science Society of America, Inc., Madison, Wisconson, pp: 1146-1162.
Sparling, G.P., L.A. Schipper and J.M. Russell, 2001.
Changes in soil properties after application of dairy factory effluent to New Zealand volcanic ash and pumice soils. Aust. J. Soil Res., 39: 505-518.Direct Link |
Tomer, M.D., L.A. Schipper, S.F. Knowles, W.C. Rijkse, S.D. McMahon, C.T. Smith, A. Thorn and T. Charleson, 1997.
A land based system for treatment of municipal wastewater at Whakarewarewa Forest, New Zealand-characterisation of soil, plant, groundwater and wetland components. Rotorua, New Zealand Forest Research Institute Limited.
US EPA., 2004.
Guidelines for water reuse. EPA/625/R-04/108, U.S. Agency for International Development, Washington, DC., USA.
Wellington Regional Council, 1999.
Regional plan for discharge to land for the Wellington Region. Wellington Regional Council.
Wellington Regional Council, 1999.
The State of the Environment Report-measuring up. Wellington Regional Council.