When watering fruit trees, it's crucial to focus on the right amount of water per week rather than how long or often to water. A general guideline is to provide one gallon of water per square foot of tree per week during hot summer months, with reduced amounts in spring and fall.
To determine the appropriate amount of water, consider the area inside the tree's drip line or the shaded area at noon. For example, a tree with a width of about six feet (spanning your outstretched arms) has an area of approximately 27 square feet and requires 27 gallons of water per week during summer. Providing more water than this will go unused, while significantly exceeding this amount (about three times more) can drown the tree. Less water will cause the tree to stop growing until spring, which is desirable if you prefer a less vigorous tree.
To deliver the right amount of water, consider three factors:
The speed of water delivery,
The duration of watering, and
The frequency of watering.
It's essential to address all three. Focusing on just one or two won't provide an accurate result.
An Example: A common type of irrigation emitter is a bubbler that delivers one gallon per minute. At that rate, the 27 sq ft tree described above needs 27 minutes per week of irrigation. Rounding the numbers, that's about 30 minutes once per week, 15 minutes twice per week, or even 4 minutes daily. Using more than one bubbler might be a good strategy to more evenly cover the entire area. Rounding again: 4 bubblers will deliver the necessary water in 7 minutes per week, which could be applied in a single irrigation, 1 minute each day, or any other suitable combination of days and durations. You can even consider a monthly watering schedule. However, a monthly program may be risky on sandy soils that don't hold enough water in the root zone. Daily, weekly, or monthly watering can all be considered as long as you deliver the amount of water the tree needs.
A Martial Cottle Park Example:
We use 0.4 gallons per hour (gph) Netafim emitters in our orchard, with one emitter for every 3 square feet of tree area. This configuration allows us to water any size tree on the same schedule. Since one emitter provides water for 3 square feet, each one must be used to deliver 3 gallons per week. A rate of 0.4 gph translates to watering for 7.5 hours per week (around one hour daily). We water for 2.5 hours every 3 days, slightly below the recommended amount. This approach relies on the trees' roots extending beyond the watered zone to absorb moisture from winter rains that remain in the soil.
Summary: Evaluating a tree's watering plan solely based on frequency or duration is insufficient. To ensure adequate watering,
consider the speed of water delivery, the watering duration, and the watering frequency. You must account for all three factors to deliver the right amount of water to your trees.
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