La fertigation in fruit trees It has become an essential tool for any farmer who wants to produce more and better, without wasting water or fertilizers. Far from being a fad, it is a way of manage irrigation and nutrition finely, almost "on demand", adjusting what the tree receives at each moment of its cycle.
When the system is well designed, the fertilizers are chosen correctly, and plan your irrigation wisely, the Fertigation allows for increased yieldThis improves fruit size, color, and firmness while simultaneously reducing environmental impact. However, if done incorrectly (poor filtration, incompatible mixtures, poorly placed drippers, etc.), problems quickly arise. Therefore, it's worth carefully reviewing all the key points.
Selection and design of the fertigation system
A project of fertigation for fruit trees Always start by choosing the right equipment: not only does the purchase price matter, but also its lifespan, the maintenance it will require, and whether it's suitable for the type of water, soil, and crops you have. properly sized drip irrigation And protected, it prevents blockages, distributes water evenly, and ensures that nutrients reach where they need to go: to the active root zone.
Leakage: the system's first line of defense
La filtration of irrigation water This is the number one critical point in any drip irrigation system. Even if the water appears clean, it almost always carries fine sand, silt, organic matter, or mineral deposits that, over time, end up clogging emitters. Disc (or ring) filters are the most commonly used in orchards because they retain small particles very well and maintain a stable flow rate.
They can be used on small farms mesh or manual filtersThese are more economical but require frequent cleaning to prevent pressure drops. For medium and large farms, it's worthwhile to switch to automatic self-cleaning filters, which clean themselves when they detect a pressure drop, significantly reducing daily work while maintaining filtration quality.
Ideally, you should assemble at least two filtration stagesA primary filtration stage (cyclone, hydrocyclone, or sand filter) captures coarse particles and sand, followed by a secondary stage with a disc or fine mesh filter for small sediments. The degree of filtration is always adjusted to the actual water quality and the diameter of the emitters to be used.
Valves, pressure regulation and safety
To make the facility manageable, the property is divided into irrigation sectors or blocksEach one is controlled by an independent valve. At the head of the system, a pressure regulator must be installed to maintain a stable working pressure (usually between 1 and 2 bar in drip irrigation), along with strategically placed pressure gauges to detect pressure drops that may indicate leaks or blockages.
In addition to pressure control, it is essential to install air valves and discharge valves at the high and low points of the network. These components help purge air, prevent water hammer, and reduce cavitation in the pumps, extending their lifespan. In automated systems, each section typically has a solenoid valve connected to a central programmer or controller.
One element that can never be missing are the non-return valves in the injection line of fertilizers. Its function is to prevent the return of the nutrient solution to the well, pond or general network, avoiding contamination by fertilizers or acids.
Emitters and arrangement of drippers under fruit trees
The choice of emitters is based on the flow rate required by each tree, the soil type, the length of the lines, and the slope of the land. In medium or large fruit trees, it is very common to place several 4 L/h drippers per plantdistributed in a ring beneath the canopy, so that the moist bulb thoroughly covers the area where the fine roots are located. In many cases, the fertilizer placement in the line It makes a difference in absorption and efficiency.
In plots with steep slopes or very long branches, the following are highly recommended: self-compensating drippersThese pipes are capable of maintaining the same flow rate even when the pressure varies along the pipeline. This feature is key to ensuring that the trees at the beginning and end of the line receive the same amount of water and nutrients.
In sandy soils or for shallow-rooted fruit trees, such as blueberries, raspberries, or blackberries, it is preferable to place the emitters somewhat distant from the trunkbetween 20 and 30 cm, and gradually move them outwards as the canopy diameter increases. This way, watering and fertilizing are applied precisely where there are the most absorbent roots, avoiding direct contact with the trunk and reducing disease problems.
Fertilizer pumps and injection
For the entire system to function correctly, it is essential properly size the irrigation pumpWhether submerged or surface-mounted, it's necessary to calculate the maximum flow rate required (the sum of all sectors that can be irrigated simultaneously) and the pressure needed to overcome pressure losses in pipes, filters, and fittings. Centrifugal pumps are the most common, and when the budget allows, they are often paired with a variable frequency drive (VFD) that optimizes energy consumption by adapting the flow rate to the actual demand.
Regarding fertilizer injection, in fertigation they are mainly used Venturi mixers and dosing pumpsVenturi injectors use the pressure difference in a narrowed section of the pipe to draw fertilizer from a tank; they are simple, inexpensive, and robust, although somewhat limited when high precision or high doses are required. dosing pumps They are the usual choice in professional facilities where several nutrient tanks are managed.
The diaphragm or piston metering pumps These advanced pump heads allow for very precise dosage control, can be programmed to inject different stock solutions, and are the standard choice in professional installations that manage multiple nutrient tanks (calcium nitrate, phosphates, potassium, micronutrients, acids, etc.). They also include tank agitation systems and online pH and electrical conductivity (EC) measurement.
Agronomic management of water and nutrients in fruit trees
The success of the Fertigation in pome, stone or berry fruit trees It depends on both the quality of the equipment and the irrigation and fertilization strategy. Simply injecting "a little of everything" year-round is not enough: applications must be adjusted to the crop's actual needs, the soil type, and the climate, using objective data (analyses, sensors, water balances) and reviewing the schedule as the season progresses.
Water requirements and irrigation scheduling
The basis for defining irrigation is the crop evapotranspiration (ETc)That is, the water lost by the soil and the plant through evaporation and transpiration. It is calculated from the reference evapotranspiration (ET0) and the crop coefficient (Kc) specific to each species and phenological stage. To this must be added the soil's water retention capacity, which tells us how much usable water the root profile can store.
Berries, and especially blueberries, have a shallow root system and are extremely sensitive to both water stress and waterlogging. In these cases, it is recommended to maintain the soil water potential around -10 kPaIn practice, this translates into short, frequent waterings that keep the first 40-60 cm moist, without saturating the pores.
Support from humidity probes, tensiometers or capacitive sensors It is very useful for fine-tuning the frequency and duration of irrigation. Several studies have shown that when irrigation is based on actual soil information rather than "out of habit," water savings of around 40% can be achieved without reducing fruit production or quality.
Nutritional balance and extraction curves
Fertigation aims to supply nutrients in a way that... fragmented throughout the cycleFollowing the absorption curve specific to each crop. In blueberries, for example, nitrogen needs are concentrated in spring and summer, with annual doses that usually range between 60 and 150 kg N/ha, depending on production and soil fertility.
This fruit tree is best managed with ammoniacal sources of nitrogen (As the ammonium sulfate) at the beginning of bud break. As fruit set and filling approach, the supply of soluble nitrogen is reduced and the potassiumThis is essential for achieving good size, sugar content, and firmness. It is common practice to almost completely reduce nitrogen a few weeks before harvest to improve post-harvest quality.
In young plantations or nurseries, fertigation is often combined with cover subscribers At the end of winter dormancy, apply approximately 30-40 kg/ha of N and P to ensure vigorous growth. After harvest, a nutritional boost is usually applied with nitrogen and potassium (20-30 kg/ha of each) to replenish reserves and prepare the tree for the next cycle.
In all cases it is essential to back up the subscriber plan with periodic soil and leaf analysesThese analyses allow for adjusting doses, detecting hidden deficiencies or excesses of certain elements, and fine-tuning the fertilizer mixtures used in the irrigation head.
Fertigation in a Mediterranean climate
The zones of Mediterranean climate They exhibit a very particular pattern: hot, dry summers, mild, rainy winters, and variable springs and autumns. This seasonality necessitates adapting both the irrigation and fertilization programs to maximize the use of rainwater and minimize losses due to leaching.
Seasonal adjustment of irrigation
During the summer, water demand is at its peak, driven by high solar radiation and temperatures. At this time, frequent irrigation is common to prevent the soil from becoming waterlogged. water stress between irrigationsadjusting the application time to the soil infiltration rate to avoid runoff.
In autumn and winter, rainfall can even cover most of the water needs. Therefore, it is advisable to accurately measure or estimate useful rainfall (using rain gauges and water balance) to reduce irrigation input. Keeping irrigation on when the soil profile is already saturated promotes nutrient leaching and represents an unnecessary waste of water and energy.
Risk of nutrient leaching
During periods of heavy rainfall, especially on light or sloping soils, there is a high risk of nitrogen and potassium losses to deeper layers. To reduce this problem, it is recommended to split the applications, avoid applying large doses of highly soluble fertilizers just before a storm, and concentrate most of the nutrients in the dry months, when the plant can absorb them.
Intelligent management combines climate information, soil moisture data, and saturated extract or soil solution analyses to make decisions when and how much fertilizer to injectThis achieves efficient irrigation in Mediterranean climates, maximizing the water used by the plant and minimizing losses due to runoff or deep percolation.
Current technologies and proportional fertigation
Advances in recent years have transformed many irrigation heads into true fertigation control centersToday it is possible to manage dozens of sectors, several fertilizer tanks, an acid tank, pumps, automatic filters and pH and EC measurement systems from a single controller, all programmable by time, volume or even based on sensors and climate data.
Automatic controllers, sensors and smart irrigation
Modern controllers allow you to define highly flexible irrigation programsIrrigation can be scheduled by the minute, by cubic meter applied, and can be triggered when soil moisture falls below a certain threshold or based on accumulated solar radiation. Some systems include alarms, historical records, PC or GSM connectivity, and can be monitored from a mobile device.
This is in addition to the deployment of soil and climate sensors Connected to IoT platforms, volumetric probes, tensiometers, and EC sensors of the soil solution monitor in real time how much water remains available in the root zone, preventing both drought and prolonged waterlogging. Meteorological data (temperature, wind, radiation, ET0) are integrated to adjust the schedule almost on the fly.
Proportional fertigation and control by EC and pH
The call proportional fertigation It goes a step further and adjusts the fertilizer dose based on the volume of irrigation water flowing through the pipe. In practice, multi-way injectors or pumps are used to dose from different stock solution tanks (for example, Tecnoplus soluble solids or liquid fertilizers like Fertigota), and the system automatically calculates how much to inject at any given time.
In this type of management, it is no longer necessary to change fertilizer at each stage of the crop; what is done is modify the injection percentage of each tank and the target electrical conductivity value. The farmer sets a target EC for the fertilized water, which will be the sum of the EC of the irrigation water itself and that provided by the fertilizer, and the equipment adjusts the dose in real time.
The pH is automatically corrected by a pH regulator with acid reservoirinjector and probe. Maintaining the pH of the water in an approximate range of 5,5-6,6 improves the solubility of many nutrients and prevents precipitation in pipes and drippers, as well as promoting absorption by the roots.
Types of fertilizers for fertigation and mixtures
In fertigation, the main focus is on soluble NPK fertilizersThese fertilizers are based on nitrogen (N), phosphorus (P), and potassium (K), and may also include calcium, magnesium, and micronutrients. They are very common at the beginning of the vegetative cycle or during peak growth, and various commercial brands offer specific ranges for fruit trees, citrus, olive groves, and vegetables. An example of a commercial NPK formulation designed for fertigation is... Nitrophoska.
Solid crystalline and liquid fertilizers
Los soluble or crystalline solid fertilizers They are dissolved in containers to prepare concentrated stock solutions. They are usually presented as binary formulas (with two nutrients) or as complete NPK solutions, often enriched with micronutrients to cover the main deficiencies. There are chloride-free variants, variants with calcium, magnesium, or slower-release nitrogen.
Los liquid fertilizers They are formulated already diluted, which simplifies the preparation of stock solutions and speeds up work at the control head. They can also be binary or complete NPK and, like the solids, are chosen according to the crop's needs, water quality, and compatibility with the other products.
Compatibility, pH and water quality
When mixing different fertilizers in the tanks, care must be taken with the unwanted physicochemical reactionsFactors such as water hardness, bicarbonate content, pH, temperature, or the composition of the fertilizers themselves can cause precipitates that end up clogging filters and drippers.
A classic mistake is mixing in the same tank calcium nitrate with sulfates or phosphatesCalcium reacts and forms poorly soluble salts that settle at the bottom or inside the pipes. The solution involves separating these products into different tanks and injecting them at different times during irrigation, or using formulas specifically designed to be compatible with each other.
To fine-tune the dosage, it is good practice to prepare a small amount of nutrient solution and Check EC and pH with a calibrated meter. This way, we verify that what we calculated on paper matches reality and we can adjust the doses before adding the mixture to the entire system.
Advantages of fertigation and sustainability
When properly designed and managed, the fertigation in fruit trees It offers clear advantages over traditional base or topdressing fertilization. The main advantage is the ability to give the tree precisely what it needs, when it needs it, avoiding excesses and deficiencies, and making much more efficient use of water and fertilizers.
By injecting nutrients through irrigation, the The distribution across the plot is much more uniform.Over-fertilized and nutrient-poor areas disappear, and weed competition is reduced because fertilization is concentrated along the tree line rather than across the entire surface. This also improves nutrient absorption, as the moist area around each emitter concentrates active fine roots.
From an environmental point of view, fertigation helps to reduce the leaching of nitrates and other ions By targeting deeper layers and aquifers, it reduces the risk of eutrophication of water bodies and limits the progressive salinization of soils. In arid and semi-arid zones, where water is a critical resource, these systems can result in significant savings in applied volume without sacrificing yield.
Winter preparation and row fertilization in woody crops
The winter dormancy period is a magnificent opportunity to Prepare the fruit trees and the irrigation system looking ahead to the next season. Even though the tree is "dormant" above ground, processes continue to occur underground, and it's advisable to get everything ready before bud break.
Pruning, soil analysis and system maintenance
Winter pruning for training and cleaning allows remove dry or diseased branchesThis improves the canopy structure and facilitates more even light and air penetration. This results in better distribution of irrigation and fertilizers, as the vegetation grows more balanced.
Before defining the subscription plan, it is highly recommended to carry out a chemical analysis of soil To determine the level of available nutrients, pH, salinity, and other important parameters. Based on these results, a fertilization strategy is designed that is adapted to the crop, rootstock, and variety.
Winter is also the best time to thoroughly review the irrigation head and pipe networkCleaning filters, checking solenoid valves, leak detection, replacing damaged drippers, and flushing lines. A well-maintained system ensures uniform application of both water and fertilizers.
Incorporation organic matter (compost or manure) During this period, soil structure improves, water and nutrient retention capacity increases, and it complements fertigation very well. In some cases, compost derived from the solid fraction of slurry is even used, applied locally under the tree line.
Fertilization to the tree line versus classic fertigation
In certain woody crops, such as peach trees under dryland or limited irrigation conditions, it has been observed that subscribed to the tree line Applying a complex NPK fertilizer (for example, 14-xx-xx formulations) along the planting line in mid-winter, taking advantage of the soil's moisture level for proper incorporation, can yield very interesting results.
Comparative trials have shown that, although the total amount of nutrients is the same as in a fertigation-based strategy during the cycle, row fertilization can increase vigor, shoot length and production When done at the right time and in plots with a history of slower growth, these differences have even been observed using satellite imagery, reflecting greater vegetative vigor.
Common mistakes and practical recommendations in fertigation
A system poorly managed fertigation A well-designed system can cause as many problems as it offers advantages. Field experience has identified a series of recurring errors that should be kept in mind from the outset.
Positioning of emitters and wet bulb management
One of the most common mistakes is placing the drippers incorrectly. too close to the trunkMost of the fine roots and root hairs are concentrated near the edge of the canopy, not right next to the trunk. Therefore, constantly wetting the base of the tree is not only inefficient but also increases the risk of crown rot.
The general recommendation is to arrange the emitters forming a ring The radius should be approximately the projection of the canopy onto the ground, increasing as the tree grows. Additionally, it's advisable to check the position of the drippers each season to ensure they are not buried in plant debris or too far from the area where the active roots are located.
Poorly planned intermittent irrigation and excess water
Another classic mistake is alternating very long irrigations with periods of total droughtThis "drown-dry-drown" pattern causes water stress, fruit drop, reduced uniformity, and, in extreme cases, damage to the root system. It is preferable to use more frequent, shorter irrigations, maintaining the bulb at a relatively stable moisture level.
Prolonged overwatering also causes problems: root asphyxiation due to lack of oxygen, yellowing leaves, root rot, and reduced overall tree vigor. Therefore, it is important to have a good understanding of the soil infiltration and drainage capacity with small field tests and use sensor data to adjust irrigation times and avoid waterlogging.
Insufficient filtration and fertilizer injection failures
Installing a drip irrigation system without a system of adequate filtration This is a guarantee of problems in the medium term. Even seemingly clean groundwater contains fine particles and salts that can cause scale buildup inside the drippers. Properly sizing the cyclone-sand-disc or mesh combination according to the water quality is just as important as choosing the drippers themselves.
In the fertilization section, do not calibrate the pH and electrical conductivity meters Regular application leads to dosing errors: you end up applying more or less fertilizer than intended. A good practice is to check the equipment with standard solutions and, occasionally, prepare a known mixture in a separate container to see if the theoretical and measured values match.
La fertigation in fruit trees It integrates irrigation, nutrition, and technological control of the crop into a single system. When good hydraulic design, correct fertilizer selection, careful management of pH and EC, and data-driven programming (soil, plant, and climate) are combined, the result is more balanced trees, higher-quality fruit, and a much more efficient use of water and nutrients—something increasingly essential in any production area.
