The Master Gardener Association and the University of Arizona Yavapai County Cooperative Extension hosted a Zoom workshop on backyard vegetable garden irrigation on Tuesday, July 25.
Presented by master gardener Bill Mains, the workshop covered the importance of irrigation, different types of irrigation and choosing the right irrigation system for a garden.
Mains defined irrigation as the art and science of applying the correct amount of water needed to keep plants healthy and produce a good crop. He argued for the special importance of irrigation in a dry western climate that often has little rainfall and a long dry season, and added that most vegetable crops are not drought-tolerant.
According to Mains, vegetable plants need about one inch of water per week, and the soil should ideally remain wet just beyond the root system after each watering. During the summer months, irrigating two to four times a week is often necessary and deep-rooted plants and shallow-rooted plants also have different watering needs. Keeping soil moisture uniform has many benefits, including a reduction in soil crusting, the prevention of premature ripening, improved germination, reduced wilting, steady growth and increased fruit size.
Mains also described the different types of irrigation systems. Hand irrigation involves using a cup, watering can or shower nozzle to hand-water plants, which is simple and cost effective but can prove difficult in large gardens and in the summertime.
Furrow irrigation is often used for agricultural purposes such as furrowed rows, berry vines and fruit trees. The cost of equipment is low, as all it requires is a long hose, but in a hot climate this method produces a great deal of evaporation. Basin and berm irrigation can be used to create a miniature moat around a plant.
Micro-irrigation, which includes drip, spitter and bubbler irrigation, is the most efficient form of irrigation in use today. Drip irrigation uses plastic tubing that applies water to the surface soil frequently at a low rate to maintain optimal soil water availability in the root zone. Soaker hose irrigation is a form of drip irrigation and is best used when a garden has short rows of plants from 20 to 25 feet long. These systems deteriorate faster than true drip irrigation systems.
The advantages of drip irrigation include more efficient water use and reduced water loss from runoff, while its disadvantages include the cost of the equipment. Mains argued that the advantages outweigh the disadvantages. He added that factors to consider when selecting an irrigation system include budget, garden size, soil type and plant type.
