Technical
Coot on her nest; A healthy, well-maintained lake will attract wildfowl and add to the beauty of the scene
encourages algae growth throughout the warm surface waters. As water temperature increases, the water’s
capacity to hold oxygen decreases. For example, water at 11O
percent more oxygen than water at 27O Nutrients
C can hold over forty C.
There is a direct correlation in the level of available nutrients and the population of algae and aquatic weeds. The term eutrophication applies to the
increase in the nutrient load of a water body over time. It occurs in water bodies such as lakes, estuaries or slow-moving streams and can cause the growth of planktonic algae and blue-green algae. This results in a depletion of available oxygen in the water and will bring about an unfavourable environment, which will lead to the death of aquatic animals, including fish, bring about the loss of ecological diversity and cause bad smells. Nutrients can come from many sources, such
as fertilisers, the erosion of soil and sewage treatment plant discharges. Of all the nutrients, phosphorus and nitrogen are probably the two most widely talked about when it comes to water quality issues. Phosphorus has been identified as the single greatest contributor to aquatic plant growth, with one gram of phosphorous producing 100 grams of algal biomass. It is also the most limiting element for algal growth since many blue-green algae are unable to utilise atmospheric nitrogen. The three most common sources of nutrient
introduction are bottom silt and dead vegetation in the lake, runoff water from surrounding turf areas and the sources of incoming water such as inlets:
Bottom silt and vegetation: Vegetative life in the water and sediment at the bottom are the primary sources of nutrients. Although they only have a two-week life cycle, blue-green algae can experience cell division and double their population as often as every twenty minutes. At the end of the cycle, the plants simply die and begin to sink to the lake’s
128 I PC JUNE/JULY 2017 “
Phosphorus has been identified as the single greatest contributor to aquatic plant growth, with one gram of phosphorous producing 100 grams of algal biomass
bottom, or benthic zone. Studies at the University of Florida have
found that sediment can accumulate at a rate of one to five inches (2.5-12cm) per year in mild climates and at a rate of three to eight inches (6-16cm) per year in tropical climates. At a mid point accumulation rate of three inches (7cm) per year, a one surface acre (4000m2 lake will lose 80,000 gallons (300m3) of water storage capacity in a single year.
)
Surface runoff: The water available for surface runoff is the portion of the precipitation that is not lost via evapotranspiration and does not penetrate the surface soil to infiltrate the groundwater. Several factors affect surface loss of nutrients and pesticides, including the amount of precipitation, soil moisture content previous to rainfall, the time of chemical application and the type of fertiliser applied. Runoff can also come from surrounding turf
areas as well as roads, farms and other outlying areas. This runoff is known as nutrient loading. Leaves, grass clippings and other materials will also runoff into the lakes, placing additional burdens on the lake’s natural clean-up processes.
Incoming water source: Nutrients are also added to lakes and ponds through inlet waters coming from wastewater treatment plants and leeching from septic systems. Often, inlet waters have minimal oxygen and are loaded with phosphorus; an indication of excess phosphorus is foaming water. Turf professionals have developed creative
nutrient management approaches over recent years. Some courses have created buffer strips using plants such as reeds along waterways in order to trap sediment and act as natural filters. Others find the use of live bacteria and fungi to increase nutrient uptake. Certain grass varieties with pest resistance and tolerance to stress can be used, and integrated pest management through the use of natural predatory insects has become common practice on many golf courses.
Factors affecting nutrient leaching
- Sandy soils are more prone to leaching losses than clay soils
- Nitrogen losses can be reduced by applying nitrogen in smaller amounts on a more frequent basis
- Mixing peat moss with sand significantly reduces nitrogen leaching compared to pure sand rootzones in the year of green construction
Oxygen
Oxygen is important to all forms of life, including all sorts of water life. It supports the food chain and aids the natural decomposition process. A lake is supplied with oxygen from several sources, but primarily through photosynthesis and wave and wind action. Immediate reactions to oxygen depletion
would be fish deaths or lingering odours. Long- term issues include nutrient build-up, sludge accumulation and a chemical imbalance in the water. Oxygen depletion or stress situations occur for different reasons, but most typically happen during:
- Late at night and just before dawn
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156
