Organomineral Fertilizer for Hazelnuts: Use, Label Reading and Application

What Is Organomineral Fertilizer?

As the name suggests, an organomineral fertilizer combines two worlds in a single product: organic matter and mineral plant nutrients. The Turkish regulation defines it as “products obtained through the reaction or mixture of an organic content with one or more primary, secondary or micro plant nutrients” (Regulation on Organic and Organomineral Fertilizers, Official Gazette 29.03.2014/28956).

In practice this means the granule in your hand contains both an organic source — leonardite, compost or fermented animal manure — and nitrogen, phosphorus and potassium. The two are not bagged separately and mixed in the field; they are combined into the same granule at the factory. That is what makes the difference: the nutrient is released from within an organic matrix.

Three-Way Comparison: Chemical, Organomineral, Farmyard Manure

Property	Chemical (compound/straight)	Organomineral	Farmyard manure
Nutrient density	Very high (18-46% single element)	Moderate	Very low, variable
Organic matter	None	Present, but limited	High — this is the real source
Nutrient content known?	Yes, stated on the label	Yes, stated on the label	No, varies batch to batch
Speed of effect	Fast	Moderate	Slow, spread over years
Effect on soil structure	Negligible	Limited	Marked (water holding, aggregates)
Ease of application	Granular, easy	Granular, easy	Heavy, hard to haul and spread
Cost per unit nutrient	Lowest	Higher	Lowest if you own livestock
Weed seed / pathogen risk	None	None	Present if not well rotted

Read the table carefully: organomineral fertilizer is not an “organic product” that replaces chemical fertilizer. It is an intermediate form sitting between chemical fertilizer and farmyard manure, carrying some of the advantages of each — partially.

What Does It Solve?

1. It slows nitrogen loss

The best documented effect of organomineral fertilizer is on the nitrogen side. In an incubation study at Uludağ University, soils treated with organomineral fertilizer at 20 and 40 g/kg showed ammonium nitrogen levels rising by 71% and 73%, while the ammonification rate increased by 61-80% by the end of incubation. The same treatment lowered nitrate concentrations and thereby suppressed nitrification potential (Dindar and Yazgan Yiğit, 2023).

For hazelnuts the implication is direct: nitrate does not hold in the soil, and rainfall carries it below the root zone. Given the Black Sea region’s annual rainfall above 1000 mm and its sloping terrain, keeping nitrogen in the ammonium form for longer is a genuinely useful property. The authors read this as an increase in nitrogen use efficiency.

2. Phosphorus in acid soil — partial help

The classic problem of hazelnut soils is that applied phosphorus binds to iron and aluminium and never reaches the plant; we cover this in detail in our DAP fertilizer guide. The organomineral claim here is that organic matter surrounding the granule occupies the adsorption sites before the phosphate ions do, delaying fixation.

3. Moisture and root environment around the granule

Organic matter holds water. Keeping moisture a little longer in the few millimetres surrounding the granule helps the nutrient dissolve and reach the root during dry springs. This does not change the water regime of the whole orchard — it is an advantage at granule scale, not orchard scale.

What Does It Not Solve?

Honesty is required here, because this is the point sales pitches exaggerate most.

Organomineral fertilizer will not close your soil’s organic matter deficit. The amount you apply per decare is measured in tens of kilograms, and the organic matter is only a fraction of that. Raising soil organic matter by one percentage point requires tonnes of organic material per decare. The gap is on the order of a hundredfold.

If you genuinely want to raise soil organic matter, the route is well known: well-rotted farmyard manure, compost, green manuring, chipping pruning residues and leaving them in the orchard, and cover crops. Organomineral fertilizer does not replace these; it stands beside them.

How to Read the Label

Content requirements for organomineral fertilizers are set by Ministry legislation and vary by product group. For current requirements, rely on the product label and your provincial/district directorate of agriculture. What to check when buying:

Be careful with humic and fulvic acid claims. “Contains humic acid” on a label means nothing on its own; what matters is how much, as a percentage. If no figure is printed, the content is either very low or was never measured. Likewise, a product with low N-P-K ratios delivers little pure nutrient per kilogram. Compare not the price of the bag but the price per kilogram of pure nutrient.

When and How to Apply It in Hazelnuts

Organomineral fertilizers are predominantly base fertilizers: the phosphorus and potassium they contain are immobile, and the organic fraction needs time to break down. Their place is therefore the classic winter fertilization window of the hazelnut year.

Period	Application	Note
November – February	Main organomineral application	On moist soil, after pruning
November – December	Liming (if required)	Not at the same time as phosphate/organomineral fertilizer
March	First nitrogen application	With a separate nitrogen fertilizer
Late May – early June	Second nitrogen application	With a separate nitrogen fertilizer

Placement rules do not change in hazelnuts. The Hazelnut Research Institute’s farmer brochure is explicit: “When fertilizing hazelnuts, the fertilizer must be applied to the canopy drip line (in a band).” Fertilizer dumped at the base of the trunk is wasted; the absorbing fine roots concentrate where the branches end.

In practice: incorporate it 3-5 cm deep along the drip line. If you are using a phosphorus-heavy product and your orchard shows a phosphorus deficit, it is more effective — as with phosphate fertilizers — to place it in holes opened along the drip line and cover them with soil. Covering serves two purposes: it stops the organic fraction from drying out on the surface, and it reduces nitrogen volatilization losses.

How It Fits Your Existing Fertilization Programme

Organomineral fertilizer is a product that replaces part of your programme, not one that is added on top of it. The most common mistake is to carry out winter fertilization exactly as before and then apply organomineral fertilizer as well; that is both wasted money and nutrient overloading.

The correct approach:

1. From the label, calculate the kilograms of pure N, P₂O₅ and K₂O delivered by the amount you plan to apply.
2. Subtract those amounts from the annual requirement in your fertilization programme.
3. Cover the remaining gap with conventional fertilizers — most of the nitrogen, in particular, must still be given separately in spring.

Organomineral fertilizer alone does not meet the annual nitrogen requirement of hazelnuts. The split March and late-May nitrogen applications stay where they are.

Cost and the Support Payment Side

Let us be plain: per unit of pure nutrient, organomineral fertilizer costs more than conventional chemical fertilizer. A kilogram of nitrogen from urea is cheaper than a kilogram of nitrogen from an organomineral product. What you buy in return are the partial benefits of the organic matrix — reduced nitrogen loss and a more favourable root environment around the granule.

One factor partly offsets that price gap: a state support payment is made for the use of solid organic and organomineral fertilizers. For the payment amount, which products qualify, the application steps and the invoice/registration requirements, see our news article Solid Organic and Organomineral Fertilizer Support 2026 — it covers the current figures and the application process in detail.

Frame the decision like this: put the cost of buying the same pure nutrient as conventional fertilizer next to the organomineral cost minus the support payment. If the gap narrows, organomineral makes sense; if it is still wide, spending that money on liming or farmyard manure will return more.

Common Mistakes

1. Choosing without a soil analysis. You cannot pick a formulation without knowing which nutrient is short; organomineral N-P-K ratios vary enormously.
2. Treating it as a substitute for farmyard manure. An organic matter deficit is not closed by organomineral fertilizer.
3. Adding it on top of the existing programme. If you do not subtract the nutrients it delivers, you over-fertilize.
4. Broadcasting it and leaving it on the surface. Without incorporation, nitrogen volatilizes and the organic fraction dries out.
5. Dumping it at the trunk base. The absorbing roots are at the canopy drip line.
6. Skipping liming. No phosphorus source performs fully in an acid soil whose pH has not been corrected.
7. Buying unregistered products. Their efficacy is unknown and your support application will be rejected.
8. Buying without an invoice. An invoice is mandatory for growers who want the support payment.

Summary

• Organomineral fertilizer = organic matter + mineral nutrient in the same granule; not a blend, but combined during manufacture
• It is an intermediate form between chemical fertilizer and farmyard manure, and replaces neither
• Its best documented effect is on nitrogen: ammonium is preserved and nitrification is suppressed
• It helps with phosphorus in acid soil, but the mechanism is weaker than claimed; it is no alternative to liming
• It does not close the organic matter deficit — that needs farmyard manure, compost and cover crops
• On the label, look for the registration number, organic matter percentage and N-P-K ratios; “contains humic acid” without a figure tells you nothing
• Apply November-February, at the canopy drip line, and cover with soil
• It costs more per unit nutrient; the support payment partly offsets this
• Formulation and rate are decided by soil analysis

For the full annual calendar see our hazelnut fertilization programme, for sampling and interpreting results the soil analysis guide, and for the organic matter side the farmyard manure guide.

📚 Turkish Regulation on Organic and Organomineral Fertilizers and Soil Conditioners (Official Gazette 29.03.2014/28956) 📚 Dindar and Yazgan Yiğit (2023), Uludağ Univ. Journal of the Faculty of Engineering 28(2) 📚 de Melo Benites et al. (2022), Frontiers in Agronomy 4 📚 Ay and Kızılkaya (2022), Journal of Soil Science and Plant Nutrition 📚 Hazelnut Research Institute - Fertilization in Hazelnuts 📚 Sakarya Provincial Directorate of Agriculture and Forestry - Fertilization in Hazelnuts