The effect of the irrigation system
Introduction to the irrigation system
How long an irrigation system runs is both simple and complex. You should run your irrigation system for as long as it needs to fill the plant’s root zone. No more and no less. However, there are several variables that affect the time it takes to populate the root area and make it more complicated. Understanding these variables and how they affect watering timing is critical to water conservation.
For irrigation, you need to know
For mature plants, in almost all cases, the plants should be given an equal amount of water each time they are irrigated. To better understand this concept, it helps to know some key terms.
Soil Saturation Point – The soil contains only water and no air. Plants cannot survive such conditions.
Field Capacity – The amount of soil moisture or water content in the soil after excess water has been lost.
Permanent dead point – There is water in the soil, but the plant cannot get it, so the plant dies.
Oven dry – the opposite of saturated. Oven drying occurs when there is no water in the soil. Plants don’t live here either.
Available water capacity or water available to plants – the difference between permanent dead point and field capacity. This is the amount of water available to the plant. This is the zone where plants thrive.
Precision irrigation helps you better save water resources
Managing water effectively means watering when the water in the soil reaches a watering trigger point. A common trigger point for most plants is 50% of available water holding capacity. Precision irrigation means watering when the water in the soil reaches the trigger point and irrigating until 95% of the field capacity is reached. Maintaining this balance means the plants are never too full or too thirsty. Maintaining this balance helps plants thrive.
How fast water moves through the soil – infiltration is when water enters the soil surface, and infiltration is when water moves through the soil. Infiltration is affected by plant cover, temperature, texture, structure and moisture. Infiltration varies by soil type. For example, sandy soils have greater permeability than clay soils. A simple soil infiltration test helps determine how quickly water moves through the soil.
About irrigation you know
Plant Deep Roots – Root depth is key to watering timing. The easiest way to know the depth of a plant’s root system is through a chart. Here’s a great chart of veggies and herbs. Root depth can be easily found on your grower website or extension service website. This is important because watering goes through root zone wastewater and nutrients. Also, remember that 70% of the water a plant absorbs is in the upper half of the root zone.
Consider slopes — if you water on flat soil, the water will move down. However, if a slope is involved, the water will move in the direction of the slope, affecting the amount of water that reaches the root zone.
How Much Water Your Irrigation System Delivers – Irrigation dischargers apply water at various rates. For example, a pop-up sprinkler with a half-circle nozzle sprays 1.85 gallons per minute or 1.58 inches per hour at 30 psi and a 15-foot throw. A gallon per hour dripper delivers one gallon per hour or 1.6 inches per square foot per hour.