If the following have not been performed Post-harvest autumn fertilization, it is advisable to proceed as early as the end of January. In fact, in about fifteen days, the olive trees will slowly begin to resume vegetative activity, using the reserve substances accumulated in the trunk, branches and roots.
When soil temperature will reach 10°C, probably between late February and mid-March, the roots will begin to absorb nutrients: it is, therefore, essential that nutrients are already available in the soil to ensure optimal vegetative recovery.
At this time it is advisable to focus on fertilizers such as phosphorus (P₂O₅) and potassium (K₂O).
In the absence of specific soil or leaf analyses, it is possible to estimate the quantities of fertilizer needed based on the removals due to vegetative activity, losses due to leaching and the capacity of the soil to retain nutrients.
The dosage
Considering an average production of 50 q/ha of olives and a density of 220-250 plants per hectare, it is recommended:
– phosphorus (P₂O₅): 40-50 kg/ha, equivalent to 2-3 quintals/ha of mineral superphosphate with 18-20% content.
– potassium (K₂O): 100-110 kg/ha, equivalent to 2½-3 quintals/ha of potassium sulphate with a 50% content.
These values are indicative and should be adapted based on the results of any soil and leaf analyses.
The uptake of nutrients such as mineral superphosphate and potassium sulfate depends on several factors, including soil conditions, temperature, moisture, and microbial activity.
In general, the phosphorus from mineral superphosphate is available for uptake by plants within a few weeks of application. However, immediate availability may be limited because phosphorus tends to bind with calcium, iron and aluminum in the soil, forming insoluble compounds. The solubility of phosphorus can be affected by soil pH, it is most available in a slightly acidic to neutral pH range, and by soil temperature. Proper management of fertilization and soil conditions can improve uptake efficiency.
Il potassium from potassium sulphate It is generally available in a shorter time, from a few days to a couple of weeks after application, this is because potassium in the form of K⁺ ion is highly soluble in water and easily absorbed by the roots. The availability of potassium is influenced by the cation exchange capacity of the soil, its moisture and the structure of the soil. Well-drained soils with a good structure facilitate the movement and absorption of potassium
Pelleted organic fertilizers
It is also possible to use pelleted organic fertilizers that enrich the soil with organic matter: they are based on manure, chicken manure, bone meal or other organic materials.
Il recommended dosage varies from 0,5 to 3 kg per plant distributed under the projection of the plant's canopy and the timing for absorption is given depending on the specific composition of the fertilizer and the soil conditions slowly release nutrients into the soil as the organic matter decomposes and the subsequent mineralization of nutrients, such as nitrogen, phosphorus and potassium, this can take from a few weeks to two or three months. Soil microorganisms play a crucial role in this process, breaking down organic matter and making nutrients available to plants. Remember that after fertilization, a burial should always be carried out by lightly working the soil.
