Closer Spacing in Agricultural Drip Systems
Drip irrigation applies water directly to the soil, and then water moves through the soil profile via a phenomenon called capillary movement. Once plant roots make contact with moist soil, water uptake can take place. Since many farmers wish to use the drip irrigation system to germinate seeds, set transplants, or inject fertilizers, it is important that the entire planting bed is moistened, or "blackened", quickly and efficiently. Creating this wetted corridor is dependent upon many factors including the soil type, soil preparation, emitter flow rate, emitter location (surface or buried), and duration and frequency of operation. But emitter spacing is considered one of the most important variables.
The photograph below shows how an 8" spacing creates a wetted corridor faster than a 12" spacing, all other factors being equal. This is because the distance water must travel from one emitter before joining up with the adjacent emitter's wetting front is reduced.
Thinner Wall Tape Products to Reduce Cost
As row and field crop growers convert more and more acres to drip irrigation, drip system knowledge and expertise increases rapidly. In the early stages of adoption, growers are encouraged to use thicker mil tapes to avoid the installation and retrieval problems that may occur when novices install thinner mil tapes. But as growers gain expertise in successfully laying and retrieving tape, either for disposal or reuse, the trend is towards using less expensive, thinner mil tapes.
At the same time, manufacturing expertise has improved such that high quality, extruded tapes with walls as thin as 4 mil (0.004") are now available. These tapes include clog resistant, high uniformity precision molded emitters that are flexible and less likely to cause damage in thinner tubes, as well as color coded striping to ensure proper installation orientation. High quality, thin mil tapes are also marked with clearly legible, permanent date codes in order to more easily manage inventory and determine product performance specifications. In addition, extruded tapes allow operating pressure of 8 psi, and facilitate water drop off from the outlet as opposed to "seam travel" to unwanted areas in non-extruded, seamed tape products.
Not only do high quality, thin-walled tapes cost less to buy, they cost less to ship and install since each coil of 4 mil tape holds 15,000 linear feet of tape, and 5 mil tape holds 13,000 linear feet. Longer reel lengths also translate into few stops and less in-field coupling during installation.
All these improvements allow growers to enjoy lower tape prices without sacrificing quality or performance.