Every drop counts: Managing precision irrigation for export citrus

Despite cutting-edge systems, citrus growers risk root diseases and nutrient loss due to over-irrigation and poor system care. Netafim and other experts urge farmers to adopt low-flow drip systems, proactive maintenance, and smart scheduling to ensure every drop of water delivers maximum productivity.

South Africa’s citrus industry has some of the most advanced irrigation systems globally, yet poor management can undermine both productivity and profits. According to Coenraad Fraenkel, area extension officer at Citrus Research International (CRI), the challenge is not the technology itself but how it is managed.

Following extensive irrigation training sessions with growers, Fraenkel identified a critical concern: “The majority of producers are completely over-irrigating their orchards. This not only causes over-wet conditions that lead to various root diseases but also leaches elements from the soil that are needed for production.”

Luan le Roux, technical manager at Indigo Fruit Farming, adds that the industry’s greatest challenges are securing the right quantity and quality of irrigation water and understanding tree water requirements at different phenological stages across South Africa’s diverse citrus-producing regions. He also notes that poor maintenance remains one of the sector’s biggest vulnerabilities.

Louis Fourie, agronomist at Netafim Southern & East Africa, adds that inefficiency often starts with system design. Systems are not always matched precisely to soil type, environment, and crop demand.

Fourie asks, “If you do not know the actual capability of your system, how could you possibly know how much water you are applying and if you can apply enough to meet the tree’s requirements?”

Without proper soil and environmental analysis, growers risk installing systems that cannot deliver water uniformly, and inadequate maintenance only widens the gap.

Low-Flow Drip: Efficient by design

Fraenkel highlights the benefits of low-flow drip irrigation:

Reduces nutrient leaching compared to higher-flow systems, keeping essential elements in the active root zone.
Provides broader lateral water spread in sandy soils than conventional drip or micro-sprinkler irrigation, improving moisture distribution.
Promotes wider root development, enabling trees to access nutrients from a larger soil volume. A broader root system improves nutrient uptake and resilience.

This is provided the irrigation system is properly maintained. Fourie notes that while low-flow drip causes less wear on pumps and valves than higher-flow or micro-sprinklers, water quality remains the main risk. Clogging (physical, chemical, or biological) must be managed proactively through filtration, chemical treatments, and regular flushing.

Avoiding the pulse trap

Fraenkel recommends scheduling irrigation using the Evapotranspiration (Eto), soil monitoring (field observations and the use of sensors), while keeping in mind the crop phenology. Focus on filling the root zone to field capacity and allowing it to dry to 50–70% before re-irrigating to maintain a healthy oxygen to water balance.

Fertigation: Precision with discipline

Both Fraenkel and Fourie stress that drip fertigation is highly effective when aligned with a sound nutrient plan. Irrigation is a delivery tool, not the fertiliser strategy itself. Programs should be based on soil and leaf analysis, orchard history, and seasonal demand. Attempting to maintain static nutrient concentrations can reduce fruit quality.

“Fertigation itself does not negatively affect fruit quality. If fertilisation causes fruit quality to decline, the cause is an unbalanced or inefficient fertilisation programme,” Fourie says.

Best practices include:

Understanding fertiliser solubility and product compatibility.
Applying nutrients only when the root zone is receptive.
Flushing the system before and after fertigation.
Monitoring electrical conductivity (EC) levels to stay within crop tolerance.
Ensuring the fertigation cycle supports the overall irrigation strategy.
Keep in mind the nutrient demand during the specific phenological stage and what the effect is on fruit quality.

Visible stress symptoms such as yellowing leaves, fruit drop, or poor fruit colouring indicate that monitoring and intervention are required. Le Roux emphasises regular filtration, continuous peroxide dosing for biofilm control, and occasional “shock” chemical treatments when necessary.

Climate resilience: Using every drop smarter

Water management directly determines fruit quality and profitability. Availability affects fruit size and internal quality, two key price drivers. Le Roux notes that excessive irrigation can produce oversized fruit with poor internal quality in hotter summer-rainfall regions, while under-irrigation in winter-rainfall regions like the Western Cape can result in smaller fruit.

Fraenkel believes that the citrus sector has strong irrigation infrastructure, but Fourie notes that this infrastructure is not always used efficiently.. To address this, the CRI focuses on transferring irrigation knowledge to improve water and nutrient efficiency, emphasising careful monitoring to ensure every drop is used wisely.