Effective fertigation begins with effective irrigation. Netafim agronomist Louis Fourie shares how precision drip fertigation keeps costly nutrients right in the active root zone where crops need them most.
High fertiliser prices continue to place increasing pressure on farm budgets, but applying less fertiliser is not the answer. Instead, growers should focus on improving the efficiency of nutrient application, says Louis Fourie, Netafim Southern and East Africa agronomist.
One of the most effective ways to improve nutrient use efficiency is through fertigation, in which fertilisers are applied via the irrigation system. However, Fourie stresses that the success of fertigation depends entirely on how well irrigation is managed.
What is fertigation?
“Fertigation is the process of applying fertilisers through irrigation water,” Fourie explains.
“Water-soluble fertilisers are dissolved into solution, or liquid fertilisers are used directly, and then injected into the irrigation system at precisely controlled concentrations. This allows nutrients to be delivered efficiently according to the specific requirements of the crop at different growth stages,” Fourie says.
He says fertigation delivers nutrients directly into the active root zone, where plants can absorb them most effectively while minimising waste and environmental impact.
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Irrigation comes first
According to Fourie, efficient irrigation is the foundation of successful fertigation.
“Fertiliser is applied through the irrigation system; therefore, fertigation efficiency can only be as good as irrigation efficiency,” he says.
He advises farmers to first develop an irrigation strategy suited to the crop, soil type and conditions before integrating a fertigation programme.
Poor irrigation management, particularly over-irrigation, allows nutrients to move beyond the crop’s active root zone, resulting in leaching. Besides wasting costly fertiliser, leached nutrients can negatively affect natural ecosystems.
Better nutrient use with drip irrigation
Fourie says combining fertigation with a well-designed drip irrigation system offers significant advantages.
He explains that drip irrigation systems can achieve application efficiencies of up to 95%, allowing both water and nutrients to be delivered with the same level of precision. Unlike granular fertilisers, which depend on rainfall or irrigation to move nutrients into the soil, fertigation supplies nutrients exactly when crops need them.
As irrigation influences root development over time, feeder roots concentrate within the wetted zone, allowing nutrients to be placed precisely where active roots are located.
Design systems with fertigation in mind
Fourie says efficient fertigation should be considered from the earliest stages of irrigation system design.
“The system must be able to deliver the required amount of fertiliser within the available irrigation window.”
He explains that irrigation systems should be matched to the soil’s water-holding capacity, crop requirements and environmental conditions. This process should involve collaboration between irrigation designers and agronomists.
Fourie also highlights the importance of considering fertiliser solubility, safe application concentrations and managing the electrical conductivity (EC) of fertigation solutions to prevent salt damage to crop roots.
Automation is becoming increasingly valuable, with modern systems capable of calculating fertiliser requirements, monitoring application rates and collecting real-time data. This information helps farmers evaluate previous decisions, improve future management and reduce human error. Fourie encourages farmers to embrace these technologies.
Technology is improving precision
According to Fourie, fertigation technology has advanced rapidly alongside the wider adoption of drip irrigation.
“Modern fertigation technology has evolved from simple manual injection systems to fully automated, cloud-based platforms,” he says.
These systems allow growers to monitor irrigation and nutrient applications remotely while using sensors and data analytics to improve precision and efficiency.
Best practices for precision fertigation
Fourie recommends several practical steps to improve fertigation performance:
- Understand the solubility of fertilisers before use.
- Follow the correct fertiliser mixing order and avoid incompatible products.
- Irrigate before fertigation to adequately wet the root zone.
- Continue irrigating afterwards to flush nutrients into the root zone and clear irrigation lines.
- Flush irrigation systems regularly to prevent blockages.
- Develop a sound irrigation strategy before integrating fertigation. NB!
Fourie concludes, “Effective fertigation begins with effective irrigation. Once water is applied accurately and uniformly, nutrients can be delivered with the same level of precision, maximising both crop performance and input efficiency.”
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