A good fertilizer program should be based on the data provided by the analysis of leaves, soil, roots reserve, and irrigation water
The quality of the root system largely defines the development and vigor of the plants. Roots reserves are molecules and elements present in certain periods of time such as starch, arginine, phosphorus, and potassium.
Its function is to provide the plant with winter survival and the first growth of roots and shoots. Its location will depend on the species found in roots, trunk, shoots, crown, and darts. If these elements are at a deficient level, they can inhibit the development of the whole plant and reduce the diameter of the shoots. In roots it allows us to analyze the state of the reserves of Nitrogen (Arginine), Sugars / Carbohydrates (Starch), Phosphorus, and Potassium. This allows us to plan based on the state of post-production reserves, to see the effect of our fertilization and recess management, thus avoiding deficiencies or excesses that can bring us physiological disorders such as spring fever in grapes or problems with the fertility of the buds or final formation of the fruit.
We should consider taking samples 40 to 30 days before the first shoots, that is when the bud begins to swell when its reserve is at its maximum. Select 5 to 8 healthy trees and sample between 8- and 20-inches depth. The selected roots should be no thicker than a pencil. A 300-gram sample will be sufficient, and it is important to deliver the sample to the laboratory as quickly as possible trying to maintain a similar temperature as if the root sample were in the soil.
Nitrogen and its availability will be found in the form of arginine necessary for initial growth in the first sprouting stage and which will serve as a diagnosis of the nutritional status to make the first adjustment to the reference dose. Example: In cases of table grapes, arginine levels of 2 to 2.5% are in a desirable range.
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Autumn fertilization can determine a high content of reserves in soils with high temperatures. The normal use of arginine will depend on the starch reserves in the plant, having a balance between these elements is essential for the normal development of sprouting and the first stages of fruit development. The starch concentration will give us the reference of the accumulated energy to be able to absorb elements that require high energy consumption in their absorption, such as potassium.
As an example, in table grapes, Starch levels of around 25% are considered optimal. In the first stages of fruit growth, the provision of nutrients will depend to a greater extent on the reserves in the root, in turn having adequate levels of phosphorus and potassium will be essential for the development of the fruit and plant organs.
Phosphorus is related to the initial growth of the roots. A deficiency of this element can cause a decay in the plant because phosphorus is associated with the energy metabolism of the plant. For example, in table grapes you want to find around 0.15% phosphorus, this varies according to crop and variety. In the case of potassium, it is important to know it to know how much of this element comes from the roots for the beginning of the production phase, and with this program within our nutrition plan how much we should contribute to this at the beginning of production and observe the effects at the beginning of sprouting. As an example, and reference in table grapes, potassium around 0.35% would be in the middle range.
A good fertilizer program should be based on both characteristics of the plantation and on the data provided by the analysis of leaves, soil, roots reserve, and irrigation water. Tissue analysis is the most appropriate method to diagnose the nutritional status of the plantation and evaluate the availability of plant reserves. The soil analysis provides complementary information on the characteristics of the soil that affect the behavior of the fertilizers and the availability of nutrients assimilable by the plant. The analytical data of the irrigation water allow evaluating its quality and content in mineral salts. The root reserve analysis is due to the importance of the concentration of free amino acids increases in these organs just before sprouting, this reserve is what ensures the necessary supply for new growth. In the same way, the content of starch and phosphorus are related, giving us a reference on the potential that the plant has for the emission, growth, and development of the sprout.
The results of water, tissue, and soil will give us a clear understanding of Nutrients elements found in irrigation water and soil, elements that plants are absorbing correctly, the existence of antagonisms between ions or other interferences that impede absorptions of some nutrients.
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