Hazelnut

Nitrogen is used by plants to synthesize amino acids and nucleic acids that are necessary for all functions of the plant. Therefore, it has a major effect on crop yield and quality. While increasing soil and plant nitrogen availability enhances tree growth and vigor, a shortage of nitrogen can reduce yield by preventing full fruit growth. Adding nitrogen in excess of the tree’s demand does not increase yield and may result in loss of nitrogen to groundwater and a reduction in efficiency. Annual leaf tissue analysis can ensure that sufficient nitrogen is applied to meet the crop’s needs without wasting money on unnecessary application. Nitrogen is mobile and new leaf production is at the expense of older leaves if nitrogen is deficient. In such cases, young leaves pale as older leaves turn yellow and drop from the tree early. Excessive leaf drop results in a tree with sparse foliage. The petioles and midribs of nitrogen deficient leaves become red. Nut yield will decrease with increasing nitrogen deficiency. An annual program of nitrogen fertilizer supply is needed to ensure the long-term productivity of nut trees by replenishing soil nitrogen. Proper rates and timings of nitrogen fertilizer adapted to the tree’s nitrogen demand, in association with correct irrigation and pruning, are powerful tools for manipulating the delicate balance between vegetative and reproductive growth of nut trees. This contributes to enhancing the nitrogen use efficiency while minimizing nitrogen losses from the ecosystem. Optimal levels of leaf nitrogen in nuts are 2-3% of dry matter for mature trees. While nitrogen is required for all plant processes and in every organ, the development of the fruit represents by far the largest sink for nitrogen use in nut crops. In most of nut trees, limited application is needed during the spring flush and the remainder should be applied during late spring and early summer to meet the demands of nut fill.

Phosphorus is a vital component of adenosine triphosphate (ATP), the “energy unit” of plants. ATP forms during photosynthesis, has phosphorus in its structure, and is active from the beginning of seedling growth through to the formation of fruits and maturity.

Phosphorus is important for the general health and vigor of all plants including nuts. Some specific growth benefit that have been associated with phosphorus are: a stimulation of root development, increased branch strength, improved flower formation and nut production, improved crop quality, increased resistance to disease, and more vigorous development throughout the growth cycle.

Leaf samples collected in mid-summer should have P values greater than 0.1% of dry matter. If values drop below 0.1%, the trees will almost certainly benefit from the addition of a phosphorus fertilizer. Phosphorus deficiency in young leaves of nut trees can be recognized by a dark green, purple, or bronze color with leaves looking stained. In severe cases, the edges of older leaves become dark brown and necrosis occurs, leading to early defoliation. Phosphorus is, in general, most available to crops at soil pH between 6 and 7. When the soil pH is less than 6, P deficiency increases in most crops. If the phosphorus content of the soil is less than 20 ppm, mineral phosphorus fertilizers should be ploughed under and thoroughly cultivated in before planting, at a rate based on soil analysis. Phosphorus can also be applied in a NPK fertilizer on a regular basis (for example in fertigation).

It is involved in regulation of nutrient uptake, water balance, sugar and protein synthesis. It also helps to promote the storage of reserves in different parts of
the plants. Potassium plays a role in orchard vigor and yield, and it contributes to the neutralization of formed organic acids. It also promotes respiration and activates growth. This is an important health factor for trees because it facilitates the proper distribution of reserves between different parts of the tree. It intervenes in the regulation of the opening and closing of stomata, it plays a role in improving drought resistance via better water use efficiency, ensuring an improvement in the functioning of the stomata. Potassium promotes the setting and advances the maturation of the nuts and play a major role in oil accumulation during nut fill and helps protect against frost.

Adequate potassium is critical to sustain yields in nut tree orchards. In cases of potassium deficiency, nut productivity and quality are negatively affected. Potassium deficient trees appear pale in color and the tree slows down in growth and produces smaller-sized leaves. Perhaps the most obvious symptom of potassium deficiency appears in older leaves where chlorosis starts at the tip and progresses down the leaf margins, the area widening with time. Black walnut kernels are sometimes linked to potassium deficiency and to improve the kernel color, potassium in the sulfate or thiosulfate form is preferable to the other forms.

Muriate of potash (MOP) often causes drawbacks during drying. In other nuts it has been reported that potassium deficiency can lead to poorly filled nuts and excessive nut drop. The causes of K deficiency are primarily: limited use of potassium fertilizers, increased yield, which removes more potassium from the soil, strong soil fixation reducing soil potassium availability and excessive use of nitrogen fertilizers, particularly in the ammonium form that tends to acidify the soil and inhibit potassium uptake. If potash fertilizers are not adequately applied to replenish the soil potassium pools, deficiency will increase in severity and extent in nut trees. Like nitrogen the annual demand and removal of potassium by nut trees are high. For example, several studies show that the use of potassium in pistachio orchards increases individual nut weight (improved ounce rate), total yield per hectare, split percentage, and percentage of filled nuts and therefore reduced blanking percentage. Potassium deficiency increases the sensitivity of pistachio nuts to sunburn.

Uptake of potassium occurs primarily during nut fill, when nutrients are allocated largely to embryo development. Optimal potassium nutrition is essential for optimal production: the adequate leaf potassium range for nut trees is 0.8 - 3% dry matter. Mid-summer leaf samples are the most reliable way to assess the potassium status in nut trees.

It is an essential nutritional element for promoting healthy tree growth and development needed for top nut yields. The uptake and availability of sulfur is less influenced by soil pH and this nutrient is thus usually taken up readily across a range of orchard soil conditions. In the tree, it is incorporated into certain amino acids (cysteine, methionine) and subsequently becomes part of certain enzymes, vitamins, oils, and lipids such as sulfolipids. Once in these complex molecules, sulfur is not easily mobilized within the plant. Deficiency symptoms, therefore, will occur in the young tissues first.

Senescing leaves efficiently retrieve sulfur. As complex molecules are broken down, sulfur is converted into sulfate (SO₄^2-), which is readily transported out of the leaf and into the rest of the plant. All proteins (and therefore enzymes) need sulfur to function, as disulfides bonds stabilize their structures. Sulfur also plays a key role in nitrogen metabolism and has a vital role in fatty acid synthesis.

A large body of evidence indicates that sulfur must be an integral part of balanced fertilization for obtaining optimum crop yields of high quality (oil, protein, fatty acids, and reduced nitrates in foliage). Sulfur fertilization is a good means of enhancing the uptake and fertilizer-use efficiency of nitrogen, phosphorus, potassium and also zinc, because of the sulfur’s synergistic relationships with these elements. The adequate leaf sulfur range for nut varies from 0.18% in walnut to 0.6% in almond.

Calcium is involved in many plant processes, including cell elongation, cell division, germination, pollen growth, and senescence. One of its most important functions is the maintenance of membrane permeability and cell integrity. When it is deficient, cells become permeable and lose control over the import and export of nutrients, leading to tissue breakdown.

When calcium supply is inadequate or transport is disturbed, local calcium deficiencies will result. This can lead to physiological disorder like a reduction in leaf size, and the appearance small and yellowish leaves, which show mottling and bronzing. Trees growing on calcium deficient soils are generally damaged by rotting of the root collar and bark.

Calcium (as the ion Ca²⁺) is also an intracellular secondary messenger involved in many signal transduction pathways in nut trees. Its irreplaceable function in this role and in cell wall polysaccharide interactions is undisputed. It is through these processes that calcium is central to stress responses, cell wall growth and
remodeling, and to plant tissue development. Since Ca2+ is such a biologically active ion, its concentration and transport must be tightly controlled within plant tissue down to the level of cellular and extracellular compartments.

Calcium has an impact on the interior quality of nuts, and fertilization may have a positive or negative effect on the availability of calcium and its uptake from the soil. Fertilization in calcium deficient soils is a necessity, and this is very important in acidic soils. Calcium’s immobility in the plant requires periodic supplementation to maintain adequate levels in the upper canopy.

Calcium can be very helpful to reduce the impact of high heat on flowers, which, during flowering, can lead to pollination failure. Severe heat stress will also result in increased bud drop. After successful pollination and fertilization, the ovaries develop into the fruit and the ovules develop into the seeds, two additional processes that each have specific chemical and nutritional requirements that a pollination complex can provide. The adequate leaf calcium range is from 2% in almond up to 4% in pistachio.

In the fertilization of nut trees, magnesium contributes to the absorption and migration of phosphorus, and it improves the capturing of iron in nut trees. Its deficiency appears as chlorosis on the old leaves at the base of branches, which can fall prematurely and cause the appearance of secondary branches. Symptoms are more pronounced on leaves situated close to fruit clusters. Deficiency occurs by impairment, as well as by antagonism, with calcium and potassium.

Magnesium deficiency can occur with light, acidic soils that are prone to leaching or in soils that have received high rates of potassium fertilizers. In unbalanced soils, magnesium can limit the uptake of potassium and vice versa. Foliar sprays of magnesium are recommend in nut tree orchards during late May/early June (northern hemisphere) where required. The adequate leaf magnesium range for nut varies from 0.3% in almond to 1.2% in pistachio.

Each litre of Thio-Sul provides approximately 160 g of nitrogen and 346 g of sulfur, delivering a concentrated and efficient source of both nutrients. Its liquid formulation is easy to handle and integrates readily into modern crop nutrition programmes across a wide range of crops and production systems.

By supplying nitrogen and thiosulfate sulfur together, Thio-Sul helps maintain an appropriate nitrogen-to-sulfur balance, supports protein formation and promotes more efficient use of applied nitrogen. Its sulfur becomes available progressively as thiosulfate is converted in the soil, helping support crop nutrition throughout key growth stages.

Thio-Sul can be applied through irrigation systems, banded, broadcast, injected into the soil or incorporated into compatible liquid fertiliser blends. This application flexibility makes it a practical solution for improving sulfur nutrition and complementing nitrogen fertilisation.

Each litre of KTS supplies approximately 360 g of potash and 252 g of sulfur, providing a highly concentrated source of soluble potassium and sulfur. Its nitrate-free and chloride-free formulation allows potassium to be supplied without adding unnecessary nitrogen or chloride.

Potassium supports water regulation, enzyme activity, carbohydrate transport and the development of crop yield and quality, while sulfur contributes to protein and enzyme formation. KTS is particularly valuable during periods of rapid growth, reproductive development and crop filling, when potassium requirements can increase substantially.

KTS can be used through fertigation, in starter or side-dress programmes, in compatible liquid fertiliser blends and as a foliar treatment on selected crops. Its versatility allows potassium and sulfur to be delivered at critical stages within a wide range of crop nutrition programmes.

Each litre of CaTs supplies approximately 75 g of calcium and 125 g of sulfur, providing both nutrients in a fully soluble liquid form. CaTs combines crop nutrition with soil-management benefits and can be incorporated into a broad range of fertilisation programmes.

Calcium contributes to cell-wall strength, root development and the structural integrity of growing plant tissues, while sulfur supports protein and enzyme formation. A consistent calcium supply is especially important during periods of rapid vegetative growth and fruit development, helping support crop quality, firmness and marketability.

CaTs can be applied through irrigation systems, banded, broadcast or blended with compatible liquid fertilisers. It may also be used as a soil amendment to provide soluble calcium, support soil aggregation and water infiltration, and help manage the effects of excess sodium in saline or sodic soils.

Its fine crystalline formulation dissolves rapidly and completely, producing a clean spray solution with minimal residue. This makes K-Leaf particularly suitable for precision spraying and for situations in which crops require a rapid supplementary supply of potassium and sulfur.

Applied directly to the foliage, K-Leaf helps prevent or correct potassium and sulfur deficiencies during critical growth stages. Potassium supports water regulation, photosynthesis, carbohydrate movement and crop quality, while sulfur contributes to protein synthesis and essential metabolic processes.

K-Leaf can supplement soil fertilisation when nutrient uptake through the roots is restricted or when crop demand temporarily exceeds soil supply. It is suitable for a wide range of broad-acre, fruit and vegetable crops and can be combined with many compatible soluble fertilisers and crop-protection products following a compatibility test.

SoluPotasse provides potassium and sulfur without nitrogen or chloride, allowing both nutrients to be managed independently within the crop nutrition programme. Its fine crystalline form dissolves rapidly and completely, making it suitable for demanding fertigation applications.

Potassium supports water-use regulation, enzyme activation, carbohydrate transport and crop quality, while sulfur contributes to protein formation and nutrient metabolism. SoluPotasse is particularly useful when crops require additional potassium but no further nitrogen, including during fruit, tuber and grain development.

SoluPotasse can be applied through fertigation and other systems designed for fully soluble fertilisers. Its low-chloride, nitrogen-free composition makes it well suited to chloride-sensitive crops, saline growing conditions and fertilisation programmes requiring precise control of nitrogen and potassium inputs.

The chloride-free, nitrogen-free formulation of GranuPotasse provides an efficient source of potassium and sulfur, making it ideal for chloride-sensitive crops and high-value production systems. The uniform, free-flowing granules ensure accurate spreading, easy handling and consistent field performance.

By supplying potassium and sulfur in readily available forms, GranuPotasse supports water regulation, enzyme activation, carbohydrate transport and protein synthesis, helping improve crop yield, quality and marketability. It is particularly beneficial for fruit, vegetable and other high-value crops where crop quality, storage life and export potential are essential.

GranuPotasse® is suitable for pre-plant, basal and in-season applications and can be broadcast, banded or incorporated into the soil. It also blends readily with many granular fertilizers, providing growers with a flexible solution for balanced potassium and sulfur nutrition across a wide range of cropping systems.