Sub-surface drip irrigation has had a major impact on the cotton industry. In areas with limited water supply, like West Texas where efficiency is a must, subsurface drip has made it possible to get the most of the water available. Drip Irrigation has not only allowed water to be conserved but has also increased production to an all time high.
Sub-surface drip is installed 10”-14” deep, between the rows of cotton. Most applications use the 13 or 15 mil tape for a more permanent application. Using GPS technology, the field is mapped for size and topography. Then the field is designed for maximum uniformity. The field is then broken down into multiple zones that allow the irrigation cycle to be adjusted in case there is a drop in the amount of available water.
The systems use disk type or sand median filters for maximum filtration. Chemical injectors are installed at the filter station to inject some types of fertilizers, pesticides, or herbicides, as well as products to clean the system. This adds to the efficiency by taking the fertilizer directly to the root.
There can be many factors that determine tape size, emitter spacing, and flow rate. Therefore, the key to making a system work is proper design and filtration. The system must utilize the proper components to make the system more efficient as well as making the system function properly over a longer period of time. The drip system if designed and installed properly, gives the producer a brighter future in the cotton farming industry.
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Drip irrigation applies water directly to the soil surface or subsurface and allows the water to dissipate under low pressure in a predetermined pattern. A wetted profile develops in the plant's root zone beneath each dripper. Ideally, the area between rows or individual plants remains dry and receives moisture only from incidental rainfall. The advantages of drip systems are that the water is applied directly to the soil in a smaller wetted area reducing evaporation and water consumption by weeds while operating at a lower pressure.
Micro irrigation systems apply water on a high-frequency basis and create a near optimal soil moisture environment for the crop. Under proper management, micro irrigation saves water since only the plant's root zone is supplied with water and little, if any, is lost to deep percolation, consumption by non-beneficial plants, or soil surface evaporation. Some movement of moisture below the crop roots is necessary to prevent excessive salt buildup in the root zone.
Micro irrigation systems are useful and suitable for sloping or irregularly-shaped pieces of land that are impossible to flood or sprinkler irrigate. A relatively small elevation drop is enough to operate a micro irrigation system on gravity pressure.
Micro irrigation systems operate at relatively low pressure compared to sprinkler irrigation. For this reason, pumping costs are substantially less than sprinkler systems. A pressure regulator is used to control the lateral line pressure. Multiple pressure regulators may be desirable for locations with large elevation changes. However, if pressure-compensated drippers/emitters are used, less pressure regulation at the laterals is needed.
Different types of drippers and micro sprinkler emitters are available and vary in purpose and cost. Our NGR Heavy Wall Dripper Line and Drip Lite Dripper Line are ideal for tree crops or sparsely planted row crops. Our P.C.2 Inline Pressure Compensating Dripper Line is excellent for sloping terrain where it allows extension of laterals and saves on pressure regulators.
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Drip emitters are usually preferred in orchards because they enable one to irrigate alternate tree rows without wetting the soil around adjacent rows, as would happen with micro sprinkler/sprayer designs. This alternate row irrigation is important with orchards because alternate rows may be planted with different varieties that require stress at different dates prior to harvest. Closely spaced (hedgerow spacing) trees are better suited to drip emitters since there are many emitters per acre in hedgerow spacing. The wetted soil volume is high, and micro sprayer/sprinkler designs suffer from problems of tree and trunk interference of the sprayer patterns. In the case of orchards or vineyards with a single hose per row, the hose is generally installed down the plant row. It is placed on the soil surface right next to the tree trunks with only a small percentage of extra length (1.5 – 2.5%) to accommodate hose expansion and contraction due to temperature changes.
Orchard and vineyard drip systems were well established on large acreages in many areas of the world by the 1980s. The equipment has continued to improve, with excellent choices now available of well-designed emitters and hoses. Eurodrip has a wide selection of products that are ideal for orchards in both surface and subsurface applications. Eurodrip’s P.C.2 Inline Pressure Compensating Dripper Line is perfect for orchards with undulating terrain and offers the widest pressure compensation range (6-65 psi) in the industry. Our NGR Heavy Wall Dripper Line leads the industry in water uniformity with a CV performance of less than 3%. The NGR is excellent for high-pressure operations, including reliable flushing in the most extreme conditions. Finally, our Drip Lite Dripper Line offers the same high-performance emitters as our popular NGR product line but with a thinner wall to provide a more cost-effective solution. All of our products have standard and custom emitter spacing available in multiples of 8 to 60 inches and can be made in custom coil lengths.
Drip and Micro Irrigation for Trees, Vines and Row Crops
By Charles M. Burt and Stuart W. Styles
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Eastern United States Drip Irrigation Practices
Drip irrigation is an extremely efficient method of applying water and nutrients to crops. In the Eastern United States most thinwall drip irrigation is used for fresh market fruits and vegetables. For many crops, the conversion from sprinkler to drip irrigation can result in water use reductions of 50% and can double yields. This is a result of improved water and fertility management and reduced disease and weed pressure. When drip irrigation is used with raised beds and polyethylene mulch, yield increases can be even greater.
These benefits are only possible when a drip irrigation system is properly designed, managed, and maintained. Irrigation water management and system maintenance are also extremely critical in order to succeed with drip irrigation. Many growers appreciate the high quality and plugging resistance of Eurodrip products.
Although many advantages favor installation of a drip system, there are some limitations as well.
1. Smaller water sources can be used, as drip irrigation may require less than half of the water needed for sprinkler irrigation.
2. Lower operating pressures mean reduced energy for pumping.
3. High levels of water management are achieved because plants can be supplied with precise amounts of water.
4. Diseases may be lessened because plant foliage remains dry.
5. Labor and operating costs are generally less, and extensive automation is possible.
6. Water applications are precisely targeted. No applications are made between rows or other non-productive areas.
7. Field operations such as, harvesting can continue during irrigation because the areas between rows remain dry, resulting in better weed control and lower production costs.
8. Fertilizers can be applied efficiently through the drip system.
9. Watering can be done on varied terrains and in varied soil conditions.
10. Soil erosion and nutrient leaching can be reduced.
Disadvantages or problems
1. Initial investment costs may be more on a per acre basis than other irrigation options.
2. Management requirements are somewhat higher. A critical delay in operation decisions may cause irreversible damage to crops.
3. Frost protection that can be achieved by sprinkler systems is not possible with drip systems.
4. Rodent, insect, or human damage to drip tubes may cause leaks.
5. Filtration of water for drip irrigation is necessary to prevent clogging of the small openings in the drip line, however a quality emitter such as Eurodrip is “more forgiving” than others.
6. Water distribution in the soil is restricted.
Drip Irrigation System Components
A drip irrigation system has SIX major components.
1. Delivery System
Mainline distribution to field
Drip tube or tape
3. Pressure regulators
4. Valves or gauges
5. Chemical Injectors
Positive displacement injectors
Pressure differential injectors
How these components are put together, and which options are chosen, will depend on the size of the system, the water source, the crop, and the degree of sophistication desired.
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