The most overlooked ingredient in fertigation

No fertigation precision without water analysis

Every fertigation programme begins with a recipe — a balanced blend of fertiliser nutrients and water designed to give your crop exactly what it needs.

Most growers spend plenty of time perfecting the fertiliser side of that recipe: choosing the right formulation, timing applications and calibrating delivery systems. Yet there’s another (commonly overlooked) ingredient in every mix that matters just as much:

Water.

Water is the foundation and carrier for fertiliser. The minerals and chemical properties in the water you use determine how well nutrients dissolve, interact with, and reach your plants. 

Just like in any good recipe, the quality and balance of the ingredients make all the difference.

When things go wrong with fertigation, it’s easy to assume the fertiliser is the main culprit. But often, the real difference lies in the water.

That’s why we believe water analysis is one of the most underrated habits in modern farming.

Understanding what’s really in your water

Unless you’re paying a fortune for reverse osmosis, irrigation water is never just pure H2O. Its chemical composition changes depending on the source and season. Even subtle changes can have a big impact on how effectively your fertigation system performs.

Take this common scenario: a grower notices uneven growth and clogged drippers halfway through the season. The fertiliser mix hasn’t changed, the system is working fine, yet results are inconsistent. A water analysis shows rising bicarbonate levels in the borehole water. That single change affected how nutrients dissolved, leading to small blockages that built up over time.

Solid fertilisers, often used in open-field farming, break down slowly in the soil over weeks or months. Water-soluble fertilisers used for fertigation dissolve instantly and move through irrigation lines. That speed is an advantage, but it also means water quality is a critical factor in how evenly and effectively nutrients are delivered.

Irrigation water, whether it comes from a borehole, dam, municipal supply, or rainfall, carries its own mix of dissolved minerals and salts. These include pH, hardness (calcium and magnesium), salinity (total dissolved solids), bicarbonates, sodium, and sometimes trace elements like iron or manganese. The sodium adsorption ratio (the balance between sodium, calcium, and magnesium) also affects how water interacts with soil and roots.

When any of these factors drift from their ideal range, the balance of your fertigation mix changes. Nutrients can bind together or drop out of solution, leaving plants underfed and systems at risk of scaling or clogging. The effects may start small like uneven growth and slower yields, but they add up.

Because water composition shifts naturally over time, a fertigation plan that worked last season might not perform the same way this season.

So understanding your water isn’t about finding “good” or “bad” water; it’s about knowing exactly what you’re working with and adjusting your fertigation recipe to get the best from it.

Routine water analysis matters

If fertigation is a recipe, think of water analysis as the equivalent of tasting while you cook.

Regular analysis shows how the ingredients in your water are behaving. Fertigation is as much about chemistry as it is about irrigation. Every element in the mix interacts in different ways, affecting how nutrients stay available to plants. Frequent testing helps you track changes in your water source and understand your current water chemistry. 

Armed with this data, you can tweak your fertigation mix to balance nutrients, adjust acidification, or change application rates to keep nutrients fully soluble and accessible to your plants.

If the chemistry of it all isn’t up your alley, you might consider an agronomist to help you understand the data and guide you in your course of action. Our own agronomy team have been translating water analysis into practical, crop-specific action plans for decades.

Also, every system and water source is different, and building around your real water conditions, from the start, helps ensure that what runs through your lines is what your plants actually need, in the form they can use.

Water Knowledge Is Growing Power

Growers who treat water testing as part of their routine, not just a troubleshooting step, see the benefits every season: stronger plants, fewer blockages, and more predictable yields.

When you know what’s in your water, you can control how nutrients behave, protect your system, and get more value out of every litre. As rainfall patterns and water sources shift, that kind of insight isn’t optional anymore. It’s the foundation of sustainable, precision farming.

For help interpreting your water analysis or planning the right fertigation strategy, contact our agronomy experts on +27 21 987 6980 or info@vegtech.co.za