Understanding Irrigation Principles in Hydroponic Culture

One of the key facets of hydroponic culture, yet also one of the biggest causes of problems that one comes across on farms on a regular basis is the lack of understanding of the principles of good irrigation.

Pressure to Increase Production and Rising Input Costs

The industry, like all other industries these days, is under continuous pressure to increase production while facing continuously rising input costs, yet many growers continue to irrigate in ways that do not promote good production.

Maximizing Yields in Pot Culture Systems

The pot culture system such as that used by most tomato, sweet pepper and cucumber growers in South Africa may be outdated, but that doesn’t mean that good yields cannot be achieved using this system, provided good irrigation practices are used in conjunction with good equipment and a good growing medium.

Challenges of Clock Timer Irrigation

So why can’t we just irrigate with a clock timer at predetermined intervals which are altered on a seasonal basis to achieve a targeted overdrain percentage?

Variability in Water Uptake by Plants

The reality is that plants do not take up water like clockwork and can vary this uptake substantially on a day-to-day basis. For example, mature tomato plants can take up 2 500ml one day and 300ml the next as the weather changes. Manual adjustments cannot adequately compensate for this, with the result that plants are often too wet or too dry, at the wrong time of the day, and production losses are inevitable. Also, it becomes very difficult to manage EC.

Factors Influencing Water Uptake

The uptake of water is strongly correlated to light intensity and accumulated light energy and is influenced by temperature, humidity, air movement and the leaf area of the plant. Using a solarimeter to assist your irrigation controller is a reliable means of scheduling irrigation to coincide with the prevailing light conditions, by far the largest determinant of water uptake, and using a reliable water content meter or, alternatively, a scale system which weighs the bags continuously will complete the picture.

Simple and Effective Irrigation Management Tools

This does not have to be an elaborate, expensive system and can either be a scale hooked up to a computer for logging purposes or a simple one with a digital display which can be read at certain times of the day.

Ensuring Control Through Water Content Management

Knowing what is going on in the bags or slabs is one of the mysteries of hydroponics, yet managing water content is one of the few things over which we can have complete control. One just needs to have the right tools.

Making Informed Irrigation Decisions

Using the tools mentioned above, you can make important decisions as to when and how much irrigation is required on a day-to-day basis, as well as refining your general irrigation strategy for the steering of your plants.

By: Martin von Holdt