Avocado Production: Nutrient Balance for Export Success (Part 1)

Avocado growers know how unpredictable each season can be. One year the trees carry a heavy crop of small fruit; the next, poor flowering leaves volumes too low to meet export contracts. Add grey pulp, uneven quality, and the ever-present risk of Phytophthora root rot, and profitable production becomes an ongoing struggle.

In many orchards, soil and tissue tests read within "adequate" ranges, yet trees still underperform. Fertiliser gets added in hope rather than precision, costs rise, and yields stay erratic. The problem is rarely shortage alone. It is imbalance and availability.

The approach, section by section

A different lens: nutrient ratios, not isolated numbers

Instead of viewing each nutrient in isolation, DRIS evaluates the ratios between elements to identify which nutrients limit performance and which suppress others. That reveals the root causes of poor fertiliser response, imbalances that traditional analyses often miss.

For avocado, DRIS combines soil, sap and tissue analysis into a single monitoring protocol that tracks how nutrients move through the plant across key growth stages. By comparing storage (tissue) with plant-available forms (sap), it shows where shortages will develop before they hit yield or quality.

It's the only system that presents sap and tissue data in a single graph. You can see at a glance how nutrients are stored and how they are being converted and used.

Charles le Roux, Director, DRIS

Phase 1: the pre-flowering foundation

Flowering depends on strong energy reserves and a healthy root zone long before the first buds appear. DRIS starts with a full soil analysis plus a combined sap-tissue sample taken about three months ahead of flowering. Two patterns commonly emerge:

• Compaction and aeration. Compacted soil restricts root respiration and favours Phytophthora. The fix is not just mechanical ripping but balancing available calcium to flocculate soil particles and restore oxygen flow. DRIS can even predict when compaction will recur under a given irrigation volume, so you act before root stress sets in.
• Phosphate-calcium imbalance. Fruit quality leans heavily on calcium. DRIS often finds phosphate locked up because of its imbalance with calcium, even when both totals look sufficient, weakening availability and driving disorders like grey pulp. Restoring the Ca-P balance improves fruit resilience and post-harvest quality.

Phase 2: monitoring through flowering

Between flowering and early fruit set, nutrient demand shifts fast. Sampling every four to six weeks catches corrections that seasonal testing misses. Low sap Brix with poor nitrogen conversion signals that trees lack the energy (ATP and NADPH) to turn nitrogen into amino acids and proteins. DRIS reads this through:

• Rising nitrate and ammonium without conversion to total N
• Elevated nitrite (NO₂), showing nitrogen loss, also a telltale of soil compaction
• Low energy indicators reflecting weak photosynthesis

The nitrogen is there; the tree simply cannot use it, often for want of a supporting micro-element like molybdenum or magnesium.

At the right dose, trace elements like molybdenum can make a world of difference. It's a small adjustment, but without it nitrogen stays unused and costs climb.

Ronald Schroder, Director, DRIS

P-Ca-K balance at fruit set

As fruit sets, the tree enters intense internal competition. Young fruit need a steady calcium supply to build strong cell walls, while vigorous vegetative growth draws from the same pool. If potassium climbs too high in this window, it restricts calcium mobility and redirects it away from the fruit, hurting market quality.

DRIS quantifies how phosphate, calcium and potassium interact at this stage, flagging antagonism so growers can respond immediately. With real-time data rather than seasonal averages, you can:

• Adjust the P-Ca-K ratio to actual orchard conditions
• Ensure consistent calcium delivery over the first 6-8 weeks, the critical window for cell development
• Support this season's yield without compromising next season's flowering