The next major innovation in irrigation technology was indirectly a product of World War II. By 1940, thousands of irrigators were using gravity flow irrigation techniques across the semi-arid West, either using water diverted from streams and rivers or pumped from underground aquifers. But a lot of that water was being wasted.
Researchers at land-grant universities were realizing that open, unlined ditch laterals allowed water to both evaporate into the air and seep down below the level where the roots of the plants could reach it. Also, they were limited by gravity. Water couldn't be forced uphill in an open ditch. The waste coupled with the difficulties of controlling the water meant that a better system was needed.
For years, town drinking water systems had carried water in closed metal or concrete pipes. Some agricultural inventors tried to adapt steel pipes to irrigation, cutting openings and welding on gates to match the spacing of corn rows. But these systems were way too heavy for a farmer to move from one part of the field to another as one section was irrigated and another needed water.
At the end of the war, a machinist named Pau Hohnstein was just finishing his service at the Hastings, Nebraska, Naval Ammunition Depot. While he was there, he had worked with a relatively new metal called aluminum. It was light and strong and wouldn't rust. Paul realized it was a perfect material for gravity irrigation systems. In his home garage, Paul perfected his system of aluminum pipes with evenly spaced gates to control the flow of water. He got a patent and started the Hastings Specialty Manufacturing Company.
Within a few short years, the company was successful and gated pipes were being used around the world.
The operation of gated pipe was relatively simple. The first of a series of pipes was hooked up to the output of the irrigation pump. Then several 30-foot pipe sections were fastened together to reach across the part of the field to be irrigated. Each new section of pipe had a larger collar built on it with a gasket inside and quick release hook outside. The pipes were simply slipped together with a cap installed at the end of the run. Then the farmer walked back, opening as many gates as he needed and turned on the pump.
After the water started flowing, the farmer walked to the bottom of the rows. As water reached the bottom of each row, he would either signal a helper or would walk back up to the pipe to shut off the gate.
Gated pipes quickly replaced many ditch laterals in gravity-irrigated fields.
Written by Bill Ganzel, the Ganzel Group. A partial bibliography of sources is here.