Clay Pot Irrigation

Last year an HOS friend, Wilma McNulty, gave me a photocopy of an article on clay pot irrigation that appeared in the Pome News some years ago. It was adapted FROM additions by Ted Swensen for Pome News.

David Bainbridge of the University of California tried a variation on an old irrigation method he found in a 2,100-yearold text, Fan Sheng-shih Shu. It directs one to bury an earthen jar of six liters capacity in the center of a pit. Let its mouth be level with the ground. Fill the jar with water. Plant four melon seeds around the jar. Cover with a tile. Always fill jar to the brink if the water level falls. David substituted eight-inch terra cotta pots that had their drainage holes plugged with silicone caulk. He filled the pots with water and covered them with aluminum pie pans. Water slowly diffuses through the porous walls of the pot and irrigates the surrounding soil. David planted various vegetables, flowers and even some desert plants. Results were stellar. Almost 100 percent germination of seeds occurred, growth was lush, and far less water was used than with a drip irrigation system. His pots were located six to ten feet apart for vine plants, three to four feet for corn and other upright plants.

Previously I have irrigated my vegetable garden with soaker hoses attached to a sprinkler system, but David’s system appeared to be twice as efficient as a drip system. Therefore I acquired twelve eight-inch pots, caulked the holes, and buried them in soil approximately four or five feet apart.

On May 15 I planted butternut squash, acorn squash, zucchini, patty-pan squash and two varieties of cucumbers around the pots. After the pots were filled with water, they were covered with aluminum pie pans. Windy conditions blew the pie pans everywhere so rocks were found to anchor them down. The very next day the pots needed to be re-filled and again on May 20 and May 22. It appeared that some were leaking, so on May 30 and 31 removed, recaulked and replaced them. Seed germinated, but far FROM David’s 100 percent success. The pots had to be filled every .ve days for the first month and more often as the summer days turned hot. Pot filling was done with a watering can because dragging a hose through the garden would damage fragile seedlings. The new system was becoming labor intensive. In July I gave up and put a soaker hose along the pots. There was simply not enough water available to the plants using only the pots.

The limited success of my experiment could be due to other factors. My garden is located on a terraced hillside with a southwest exposure. It is sunny and hot most of the day in summer and evaporation was probably much higher than on a level expanse. The soil had been amended with purchased compost that was very fluffy which also could have contributed to greater evaporation. Vegetables I selected for this experiment have fairly high water requirements as well. I may make another attempt this year to use my caulked pots next to tomatoes and peppers.

Pome News, Spring 2005