Q: What is an important criterion to consider for Low Pressure Center Pivot (LPCP) irrigation systems?
A: Low pressure pivot sprinkler systems are flexible in that they can be used in arid, semi-arid and humid environments, on flat or moderate slopes, in conjunction with precipitation, with row or high-value crops, and are effective in most soil types. There are four LPCP types: low energy precision application (LEPA), low pressure in canopy (LPIC), low elevation spray application (LESA), and medium elevation spray application (MESA). All four types have pressures ranging from 10 psi (pound per square inch) to 30psi at the center pivot in comparison to high pressure pivot systems that operate at the pivot over 50 psi. Although LPCPs are good for most soil types, it is a good idea to match rate of infiltration of a soil with the pressure of water to limit water loss as a result of runoff and excessive evaporation. LEPA is the only system out of four that requires additional cultural practices such as the use of furrow dikes and/or farming in a circle.

Q: How is water distributed in microirrigation systems?
A1: Drip or microirrigation systems are another name for the way in which irrigation water is distributed to a field through emitters. Three common types of microirrigation systems are micro-sprinklers/sprays, drip irrigation, and subsurface drip irrigation (SDI). Micro-sprinklers or sprays are commonly used on high-value crops whereas drip or SDI is used for row crops. A major requirement for all three systems is available water supply of sufficient water quality since all they generally operate under low pressure, low volume distribution schemes with slow but frequent water applications to the soil. Microirrigation systems also require a significant increase in capital expense and labor input. Although water conservation may be an added benefit, most producers implement microirrigation systems in order to increase crop yield and quality.

A2: Water, in drip and SDI systems, is applied directly to or just above the root zone. Direct water application to the roots of the crop rather than to the soil or the canopy of the plant prevents excess water on the surface from evaporating, limits deep percolation, and eliminates runoff, soil erosion and non-beneficial consumption. Micro-sprinklers and sprayers usually stand just above the soil where the emitters release water traveling a short distance through the air to the soil. Benefits for micro-sprinklers and sprayers include frost control, lesser susceptibility to clogging in comparison with drip and subsurface drip systems, as well as greater water application and distribution flexibility.

Q: What is surge flow irrigation?
A: Surge irrigation is a surface irrigation technique that allows the producer to control the quantity of water used to irrigate a row crop by way of furrows. Surge or butterfly valves give the producer flexibility to regulate applied water to and between furrows, alternating amount, direction, advance, and timing of the flow. Additional requirements for a surge system are timer, valve equipment, and gated or flexible pipeline. When water is diverted between furrows, the drying time allows for surface soil particles to consolidate and form a seal in the furrow thereby reducing deep percolation and uniform application within the root zone. An added benefit is a reduction in runoff due to increased uniformity of infiltration across the field but can be highly dependent on the timing of operations and soil texture, specifically medium soils with high intake rates.