The year 2024 will be remembered as the worst, perhaps ever, in terms of quantity produced. A sharp drop in production is reported in all areas where the crop is present and in a generalized manner on the different varieties present in the territory with particular accentuation on our Tonda gentile trilobata. The causes at the moment are still difficult to understand but surely the climatic extremes of recent years with the constant continuous increase in temperatures, especially in winter, have a hand in it. In all this a fundamental role is played by the soil, which can be a very valuable ally in mitigating the overlying meteoric evolutions and creating more favorable living conditions for plants. In this regard, soil management and fertilization play a key role.

In hazel, proper management of fertilization in terms of quality and quantity has the following benefits:

  • bring the crop back to high production levels
  • reduce the phenomenon of production alternation
  • mitigate late spring dropout
  • improve yield

In addition, it should be remembered that fertilization has an impact on the environment so it is necessary to know the optimal times of element supply and distribution techniques suitable for reducing the emission of greenhouse gases into the atmosphere. In this regard, burial at the same time as fertilizer distribution is always recommended.

In general terms, in post-harvest fertilization, most of the phosphorus, 2/3 of the potassium, and 1/3 is distributed in order to restore the plant’s reserves and create the best conditions for male and female flowering and subsequent fruit set. Following this, in spring, nitrogen inputs are completed in the post-flowering period and in the nut formation phase. Potassium inputs in the hazelnut swelling stage are also completed. The amounts of the three macroelements should be calculated on the basis of crop removals.
 

On average, in terms of standard doses, the average annual intakes are as follows:

Nitrogen 70kg/ha                      Phosphorus 40kg/ha                           Potassium 90kg/ha


In order to set up a fertilization plan or at any rate to be able to be guided in the choice of fertilizers, it is advisable to carry out a chemical-physical analysis of the soil, to evaluate well the vegetative state of the plants the trend of production and finally not to forget the biological component that constitutes the soil and that is a fundamental ally to the maintenance of fertility.

In the fall, it is recommended to apply fertilizers with low nitrogen titer and consequent prevalence of phosphorus and potassium. For example, with 4-8-10 fertilizer, a basic 5-6q.li/hectare or simple fertilizers will be contributed. It is always recommended to contribute organic matrices and/or organic-mineral based fertilizers. For organic farming, always check carefully that the fertilizer is allowed for use in organic.

Application of nutrients, particularly nitrogen, should be done in the immediate post-harvest period because as the fall season progresses, the plant loses its leaves and consequently no longer absorbs the element with the risk of leaching it and polluting groundwater.

In addition to the supply of macroelements, some equally fundamental aspects that interact with basic nutrition should be mentioned:

  1. Ph: Ph reaction plays a key role in regulating soil biological processes(nutrient assimilability and microbial life). Neutral soils (ph 6.6-7.3) present optimal biochemical conditions for hazel cultivation. Higher phs are often found in typical hilly soils cultivated with hazel. In these basic soils, the solubility of some macro elements(e.g. phosphorus) and microelements tends to decrease resulting in less available to crops resulting in more or less severe symptoms of nutritional deficiencies(ferric chlorosis, manganese deficiency, etc.). Consequently, from a practical point of view, it is advisable to use organic-based fertilizers containing phosphorus dioxide(acid reaction) and in cases of excessive alkalinity to start a ph correction cycle (applications for several years) by supplying sulfur products (e.g. lenticulate sulfur) with doses of 5q.li per hectare.
  2. Organic matter: organic carbon is the main food source for soil microorganisms that act by transforming organic matter by releasing plant nutrients. Optimal organic matter levels should be considered to be around 2-2.5 percent. With values below 1.5 percent, we move to a poor soil condition with a number of negative consequences for the plant. In normal cases, it is recommended to contribute properly composted and humified cattle manure every 3 to 4 years, digestates of provenance, manure-derived manure or plant matrices. In addition, preference should be given to the use of organic or organo-mineral fertilizers that have an organic matrix. We also recommend evaluating the application of microorganisms that are essential for all biochemical processes in the soil.
  3. Microelements: microelement requirements are generally met by the natural soil supply. In some cases, deficiencies may occur and should be managed with foliar fertilization in the spring period. In general, excessive use of foliar fertilizers is not recommended, but interventions at certain times can have a significant effective in overcoming stresses and on final product quality.
  4. Green manure in the management of young plants in breeding. The advantages of using this technique are numerous: first of all, the buried biomass improves the chemical and physical characteristics of the soil by increasing the organic matter content, thus improving the structure and consequently the porosity and capacity of the soil to retain water. Then, if legumes are present within the sown mixture, these, due to their ability to fix inorganic nitrogen, improve the soil’s supply of nitrogen available to plants. For these reasons, the use of green manure, by properly studying the mixture, can replace the use of manure and fertilizers. Soil cover also presents the potential action of controlling weeds, which are difficult to manage in organic farming, with a possible decrease in herbicide use. The covered inter-row during winter allows for greater protection of the soil from erosion caused by heavy rainfall and subsequent leaching of elements. The choice of essences to be sown must be studied according to the nutritional and biological needs of the soil as well as the climatic-environmental conditions affecting the plot. In general, complete mixtures have different percentages of grasses, legumes and some crucifers.
  5. Soil tillage: tillage is not recommended as it impacts the organic balance of the surface layers of the soil. With a view to promoting ‘grassing, the use of aerators/diggers is recommended to de-compact the soil without compromising the present turf.
  6. Finally, remember not to forget pruning. Plants should be pruned rationally to renew old wood and allow light to penetrate well. Only in this way can one prospect toward optimal qualitative-quantitative production.


Authors:
Maurizio Ribotta – Technical Service Cia Cuneo
Lorenzo Traversa