Carlos Tapia T. Agricultural Engineer – M.Sc Technical Director Avium; Bruno Tapia Z. Agricultural Engineer – Avium Technical Coordinator; Diego Húmeres M. Agricultural Engineer – Avium Irrigation and Climate Department.
Fertigation can be defined as the process of injecting fertilizer, dissolved in irrigation water, permanently throughout the season according to the needs of each crop. Irrigation and fertilization are two of the most relevant factors (in that order) and fundamental pillars associated with the delivery of essential chemical elements and the water demand provided. Therefore, our technologically advanced irrigation system can directly determine our success as a project, because it will help us achieve the proposed objectives that will determine the productive potential of the orchard, from the training stages to the productive stage; not leaving aside the climate, health, productive management and the variety/rootstock combination.
An effective and rational nutritional program is one of the keys to achieving our goals, but we must begin by understanding that each chemical element provided as fertilizer is essential in the life cycle of cherry trees, since each one has a specific function, the way of moving (or not) in the soil and within the plant, and the ability to express its deficiencies and excesses. From the above, it is important to understand and know that adult leaves are the indicator of the nutritional status of mobile elements, while new leaves are for the immobile elements that appear in the adapted table (Table 1).
The question that arises next is how do plants gain access to these chemical elements? To obtain the answer to plant nutrition, we must go to the subsoil, where the roots live, which absorb nutrients from the soil solution to the plant, through an active transport of ions; this requires energy and its accumulation is carried out against a concentration gradient, following synergisms and antagonisms according to their charges; in general terms, nutrients with the same ionic charge tend to compete, while those with different charges tend to favor their entry to the roots. These nutrients become available thanks to transport through irrigation water and being transferred to the different organs of the plant by transpiration and by conduction through the vascular bundles.
Now that we know that cherry trees need different essential chemical elements, how do we fertilize them? The answer comes through the irrigation system, which will be useful to provide nutritional contributions through each irrigation carried out according to the seasonal water demand and phenological stage, which we commonly call fertigation, which has some benefits:
- Application of water and nutrients directly to the volume of the active root zone, increasing the efficiency of fertilizer use, reducing losses and environmental impact.
- Precise application of nutrients according to the specific demand for each phenological stage of the cherry tree.
- Easy automation of fertilization work.
- Greater uniformity of application in each irrigation, making a continuous application process without deficit periods.
- Possibility of using low-quality water and soil.
- Greater efficiency in the use of machinery, by avoiding its traffic during fertilization work.
- Better production yields.
Despite the benefits of using the fertigation method, it must be taken into consideration that not all fertilizers are suitable for this, since this method requires that the fertilizers must have a minimum solubility and that they be compatible with each other.
As a preventive measure to avoid incompatibility between fertilizers, it is suggested to have at least two preparation ponds.
Building a fertigation program
To build a suitable program for each case, it is necessary to take into consideration the following aspects:
- Gain in-depth knowledge of the production system (soil, health, climate, nutrition, irrigation, phenology).
- Know the appropriate diagnostic techniques.
- Determine the needs and objectives to be achieved during the season.
- Define the economic aspects.
Currently, for cherry cultivation, the balance method is the most used by consultants and agronomists, and is expressed in the following formula:
Where:
- Fertilizer dose is the amount of nutrient that must be transformed into the commercial product to be used, expressed in kg/ha.
- Demand is the need for fertilizer to be used during the phenological stage, whether formation or production, considering in the latter the demand for nutrients per ton of fruit per hectare.
- Supply is the soil's contribution for each nutrient, considering maintaining a standard reserve in the soil.
- Fertilizer efficiency for each nutrient and according to fertigation, which can fluctuate between 30% – 85%.
Without a doubt, a nutritional program developed taking these aspects into account will be successful in achieving its objective, always taking into account the productive potential of the garden.
The fertigation format should be the basis of soil nutrition from an operational and technical point of view, considering the efficiency of fertilizer use and the capacity that we have as an industry to manage this work.
Do not forget that the important basis of this nutrition method is governed by the quality, implementation and management of irrigation programming, so having a system ready is the first step to achieving nutritional and productive objectives.
