Blueberry Nutrition Unlocked with DRIS (Part 1)

DRIS integrates sap, tissue, and fruit analysis into a single season-long monitoring system. By looking at stored nutrients (tissue) alongside what the plant can use immediately (sap), it pinpoints where shortages are developing before they affect crop performance.

It's the only system that shows sap and tissue data together on a single graph: how nutrients are stored, converted, and used. Critical in substrate, where conditions change fast.

Charles le Roux, Director, DRIS

1. Measure: Monthly sap and tissue tests, plus two fruit analyses to monitor nutrient movement into the berries.
2. Analyse: DRIS identifies nutrient interactions, highlighting both limiting and suppressing factors, not only deficiencies.
3. Recommend: Precise fertigation and foliar adjustments based on real-time, variety-specific requirements.
4. Monitor: Ongoing data checks confirm the plants respond, allowing mid-season adjustments where needed.

This shifts crop management from reactive corrections toward proactive, evidence-based decisions, catching problems well before they show in the field.

The operation grows several varieties to stretch its production window. DRIS quickly made it clear they behave very differently, even under identical fertigation. Some held strong energy reserves under fruit load; others dropped in nitrogen conversion and magnesium stability. In substrate, genetics largely determines how a plant handles nutrition.

Varieties may look similar from the outside, but their nutrient responses are entirely different. One nutrition plan can't optimise all of them.

Ronald Schroder, Director, DRIS

One of the season's most significant discoveries was unexpected: compaction and poor aeration inside the substrate. High nitrite (NO₂) in the sap confirmed nitrogen wasn't converting. Oxygen shortage in the root zone leads to:

• Nitrogen loss
• Reduced vigour
• Higher susceptibility to stress
• Weak resilience during bulking

Weekly liquid calcium and fulvic acid reopened pore spaces, improved aeration, and supported microbial activity. As oxygen recovered, NO₂ fell and nitrogen conversion improved across several varieties.

Micro-element balance stabilised through the season, but macro-elements proved much harder to correct mid-season, since they rely on fine root hairs for uptake.

Nitrogen conversion. Available, but not converting efficiently. High NO₂ pointed to oxygen limits, not a shortage.

Magnesium. Consistently low, limiting photosynthesis and energy during bulking.

Potassium & phosphate. Both dropped sharply in bulking, directly affecting berry size. The lesson: fix macro balance before the season begins.

• Trace elements (Fe, Mo, Zn) responded quickly to foliar sprays.
• Macro-elements (N, K, P, Mg) did not correct well via foliar. They needed fertigation.
• Calcium & manganese needed attention in both fertigation and direct fruit feeding.

This moved the farm away from broad "shotgun" trace sprays toward targeted strategies guided by limiting-factor analysis, laying the groundwork for the real test: the bulking window, where energy, Brix, calcium and manganese decide whether fruit meets export spec.