Autumn grapevine fertilization: preparing for next season

With the harvesting of grapes, whether they are for the table of for wine, the viticultural year is far from over. During fall and winter, in fact, important decisions must be made regarding various cultivation techniques, the application of which will help to lay the foundations for a good performance in the following year.

The months following the harvest are crucial for various physiological aspects of the vine. After it has made substantial “efforts” to ripen the grapes under the August sun, it deposits sugar reserves in perennial organs, stems and roots. These are months when the winegrower is called upon to make important decisions.

For example, think about what choosing the period when dry pruning is done means, given that it will significantly influence the date of the plant awakening in the following spring, and thus the greater or lesser predisposition to damage from late frosts (especially in the case of early varieties).

A use will also need to be given to the wood resulting from pruning: removal and burning, mulching and burying, mulching and the beginning of pelletizing (as fuel) or the production of biochar, with soil amendment action. Mulching followed by burial must be carefully evaluated where the vineyard is not perfectly healthy, as it can contribute to the spread of sources of diseases, such as Escoriosis.

Speaking of protection, in autumn health operations may need to be performed against powdery mildew casmotecae on infected organs, up to the phylloptosis phase, dragged along the rhytidoma by the fall rains or found on clusters fallen to the ground. Treatments with chemicals or biocontrol agents performed at this time strongly reduce the inoculum doses for the following season and delay the onset of primary infections.

Autumn also involves important decisions regarding soil management, in the inter-row and on the row, for example regarding the sowing of green manure or basic fertilization .

Of course, fertilization in the autumn-winter period also requires great attention. On the one hand, the plant must be accompanied through the dormancy phase in the best way possible, but on the other hand, it is important to reintegrate into the soil the nutritional elements removed, mainly macroelements, which occurred during the vegetative-productive season.

The quantities of nutrients to be distributed annually to the vineyard can be calculated more or less accurately, depending on the factors considered. Basically, the annual requirements need to be established (which, in the case of wine viticulture, may vary significantly for one variety depending on its oenological intended use), dependent mainly on the absorption of nutrients intended for the ripening of the clusters and the development of the foliage, with particular reference to green pruning and dry pruning wood, if the branches are removed from the vineyard.

Once the requirements have been established, the doses to be supplied annually to the land for each individual element are calculated based on the following balance formula:

D = F -A + P

Where:

• D is the dose to be supplied
• F is the requirement
• A represents the natural inputs (e.g.: mineralization of organic matter by Nitrogen)
• P represents losses (leaching, immobilization, denitrification).

If fertilization is based exclusively on the use of mineral products, the annual dose must be distributed during the two times of maximum root absorption, spring and autumn, but with important distinction between predominantly clay soils and loose soils.

If, on the other hand, fertilization is based in whole or in part on the use of organic or organo-mineral products, distributions in autumn or late winter are preferable, ensuring that no excessive amount of nitrogen is made available at the end of spring – early summer, which would push excessively on vegetative development, to the detriment of the setting process.

In the case of late harvests, autumn fertigation can be used to help the plant complete the production if its reserves, without simultaneously negatively influencing the quality of the grapes. In the case of distribution of humic extracts or protein hydrolysates, fertigation can also have positive effects on the microbiological viability of the soil.

Adequate foliar nutrition between grape harvest and phylloptosis, on the other hand, favours the extension of the so-called “Stay Green” phase, during which the leaves, while maintaining high photosynthetic efficiency, contribute to an adequate accumulation of reserves in the responsible organs and to the bud break phase.

Agribios offers a very wide range of fertilization products for wine grape and table grape vineyards, ranging from organic, organo-mineral and liquid fertilizers. More specifically:

AGRIORGANICO 10%, nitrogen organic fertilizer obtained for cold pelleting from a mixture of partially hydrolyzed animal proteins and dried manure. The size of the natural organic molecules containing nitrogen allows it to be released gradually, remaining available to the plant for longer. This translates into greater efficiency and effectiveness of the fertilizer and at the same time more respect for the environment. AGRIORGANICO 10% is a fertilizer designed specifically for organic and environmentally-friendly farming. It’s designed for use during the growth cycle of all herbaceous or tree crops needing a nitrogen supply, requiring some light work to bury it in the soil in order to preserve its biological vitality.

AGRIVIGNE SPECIAL provides, in a single step and together with the mineral fraction containing nitrogen, phosphorus and potassium exclusively from sulphate, a significant amount of highly humified organic matrix of meso and micro elements, among which Sulphur stands out. The organic matrix of AGRIVIGNE SPECIAL consists of a mixture of the best quality humidified manure, naturally fermented for a total of 180 days in a covered and ventilated place. This long period of maturation reduces the moisture content, enriches the organic substance with humic acids, neutralizes the pH and sanitizes the mass, rendering it free of nematodes, salmonella, pathogens, antibiotics and weeds seeds.

MICROTECH POWER is an extraordinary liquid organic fertilizer, inoculated with mycorrhizal fungi, to be used during the cultivation phases of all herbaceous and tree crops. Its special composition, the result of scientific research and company know-how, enables it to provide nitrogen, organic carbon, enzymes, sugars, levogiri amino acids, peptones, mycorrhizae and  rhizosphere bacteria useful to plants (PGPR, nitrogen-fixators, etc.). Made though an exclusive enzymatic hydrolysis process, MICROTECH POWER biostimulates plants by facilitating the absorption of the nutrients provided, creating a protective barrier around the roots and strengthening the plants’ defenses against biotic and abiotic stress. The amino acids contained are easily absorbed by the crop because they are present in the levogira form, which is closer to the plant’s metabolism. The microorganisms present in MICROTECH POWER (Trichoderma harzianum, Trichoderma viride, Azospirillum, Azotobacter, Pseudomonas and other microorganisms), biostimulate the crop and improve the absorption of the nutritional elements provided or already found in the soil but not used.