Walker concluded that during the drainage period, the build-up of negative pressure consolidated this thin seal and altered the permeability of the soil surface. Following this theory, surge research began to expand into establishing the most efficient surge lengths and determining how the subsequent surge cycle lengths correlate. Surge valve manufacturers took these advances in technology and redeveloped their original timers and clock-type controllers into sophisticated controllers using programmable microprocessors. This new generation of surge valves allows the grower to tailor his valve controller to soil characteristics, such as texture and infiltration rate. Programmable controllers can be modified any time during irrigation to reduce tailwater or increase opportunity times for deeper penetration of water.
Some controllers have basic built-in programs.
All the irrigator has to do is install the unit in the center of his gated pipe between two sets of pipe, enter the appropriate information, press start and let the controller do the rest. The controller directs the water to half of the gated pipe for a set time and then automatically switches to the other half. Advance cycles are repeated, with an increase in time per side, until the water reaches the end of each row. At this time, the finishing cycles begin to send water all the way down the furrow each time to achieve proper depth of penetration. By inputting certain information related to a particular field, the program automatically takes into account varying soil types, moisture content, slope, furrow size and compaction.