Aqualine

Product description and applications

Aqualine is a new generation irrigation hose for travelling irrigators and booms, and is ideally suited for:

Benefits and cost saving features

Specifications

Inside Diameter Weight (g/m) Short Length Burst Pressure (Bar)
40mm (1½") 360 50
50mm (2") 510 50
65mm (2½") 630 40
75mm (3") 800 40
100mm (4") 1100 40
150mm (6") 1500 30
200mm (8") 2100 25

The manufacturer reserves the right to modify specifications without prior notice.

Lawn irrigation

Note: this product is not suitable for fertigation.

Lush green lawns are an inspiration for the people that use them for sport or recreational activities. The maintenance and creation of lawns for school playing fields, sport clubs, golf courses, parks and gardens is supported by a huge industry employing people with specialised skills together with a range of specialised machinery.

To achieve adequate lawn growth, water and nutrients have to be applied within time perimeters that allow the replacement of depleted soil moisture reserves before temporary wilting occurs.

Soil moisture is lost to the atmosphere through evaporation of water from the surface of the grass after irrigation and through the transpiration of moisture from the leaves of the grass during growth. The combination of these two processes is referred to as evapotranspiration and is a function of climatic conditions and plant physiology. High temperatures and wind cause soil moisture levels to drop rapidly depleting reserves held in the soil. Grass lawn has a short root depth of no more than 200 mm making it one of the most difficult crops to irrigate successfully. Should the irrigation scheduling be inadequate dry areas occur and the grass wilts and turns brown.

To maintain growth and a lush appearance irrigation should be applied with a predetermined volume of water at intervals corresponding to the root development and soil type. This process is called irrigation scheduling and provides a framework for replacing soil moisture losses within a practical period of time. Soil moisture losses through evapotranspiration can be measured using various methods. The most common is to measure the daily depth of water lost from the open surface of water contained in a class A evaporation pan, which has a scale calibrated in mm. Soil Tensiometers are used in addition to the evaporation pan and are placed in the soil in and below the root system Tensiometers measure the negative pressure that exists in the soil where roots interact with water trapped between soil particles. There are also sensors that are placed in the soil that operate electrically to provide moisture level readings.

The relationship between evaporation losses from a class A pan and the water requirement of plants show that less water is required by growing plants. The rate at which plants transpire is regulated through physical and physiological processes which occur in the plant. The ratio between evaporation from an open water surface and actual plant water requirement is referred to as the drop factor. Crop factors vary between crops and during stage of growth. In the case of short grass the crop factor is in the region of 50%, which means that should the combined daily reading after four days from a class A pan be 40 mm then soil moistures levels within the soil would have been depleted by 20 mm.

It is advisable for irrigation managers to have established at least one class A evaporation pan in the area requiring irrigation together with tensiometers or sensors, bearing in mind that the efficient use of water means a saving in costs. The soil within the root zone of the short grass is the medium through which moisture and nutrients are osmotically derived and the amount of water held will depend upon the texture of the soil. It will be a determining factor in calculating the irrigation interval of cycle between irrigations. In a sandy soil the amount of water held after free drainage within the root zone, known as field capacity, could be as little as 15 mm, while in clay soil as much as 25 mm could be expected.

Having estimated the daily evapotranspiration losses at 5 mm per day during a period of peak demand, it will be seen that temporary wilting will take place in grass planted in sandy soil before the planted in a clay soil. If this reservoir of soil moisture available to the crop is not to be fully depleted, an irrigation cycle should commence at about 50% of field capacity. For sandy soil this would be every second day and for clay soil an irrigation cycle of three days might be sufficient to maintain optimum growth.

The most common method of returning water to the soil lost through evapotranspiration in a crop of short grass is through an overhead irrigation system. Overhead refers to the use of impact sprinklers in the form of buried pop-up sprinklers or self propelled linear move sprinklers with similar operating pressures of three bar. linear move sprinklers with similar operating pressures of three bar. A well-designed and managed sprinkler irrigation system should have a water efficiency of 85% and it is advisable to engage the services of an irrigation technician in order to avoid dry patches on the lawn and additional expenses.

Q&A

  1. Q: What is my application rate in mm/h if I have 4 mm nozzles spaced at 18 x 12 m?
    A: 1 000_ 18 x 12 = 4.6 mm/h (4 mm nozzles at 3 bar = 1 000 l/h)
  2. Q: What is my application rate in mm/h if I have 4.8 mm nozzles spaced at 12 x 12 m?
    A: 1 500_ 12 x 12 = 10.4 mm/h
  3. Q: How many m³ of water do I need to apply 40 mm to 12 ha of lawn?
    A: 1 mm of water covering 1 ha = 10 m3 therefore 12 x 10 x 40 = 4 800 m3
  4. Q: What flow rate do I need in the above case if my irrigation cycle is 4 days and I can pump 24 h/day?
    A: 4 800_ 24 x 4 = 50 m/h
  5. Q: How efficient is my overhead irrigation system?
    A: More water is lost to sun and wind at low application rates.The application rate should be equal to the maximum infiltration rate of the soil type for efficiencies of up to 90%.

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