Summary: Fertigation allows nutrients to be delivered to the root zone at the dose and at the time the plant needs, but it only works well when the irrigation system, the chemistry of the solution and the operating routine are in order. This article brings together eight common errors, explains why each one harms the application and shows what to do to avoid them, based on technical publications from Embrapa.
What is fertigation and why mistakes are costly
Fertigation is the application of fertilizers dissolved in irrigation water. In drip and micro-sprinkler, the solution reaches directly the volume of soil explored by the roots, which allows fertilization to be distributed throughout the cycle. Embrapa summarizes the main advantage as the application of nutrients "in the exact quantity and time required by the plants".
The same material lists the requirements: the technique requires knowledge of fertilizers and dosage calculations, and inadequate management can contaminate water sources and cause toxicity in plants. In practice, many problems come from operation details that are repeated in each application.
1. Fertigating with a system that distributes water unevenly
Fertigation inherits the uniformity of irrigation. If some emitters apply much more water than others, they also apply more fertilizer. Embrapa's publication on the topic is straightforward: the good distribution of fertilizers "depends on the good uniformity of water distribution in the irrigation system", and recommends hydraulic assessment at least once a year.
How to avoid: Before fertilizing via water, measure the flow of the emitters at representative points in the sector, check pressures at the beginning and end of the lines and correct leaks, clogged emitters and adjustment problems.
2. Mixing incompatible fertilizers in the same tank
Not all fertilizers can be used in the same solution. Embrapa's chapter on preparing solutions recommends avoiding mixtures such as calcium and magnesium with phosphates, and calcium with sulfates. Another rule mentioned is not to mix ammonium sulfate with potassium chloride, a combination that reduces solubility in the tank.
When there is precipitation, part of the nutrient is no longer available and the solid material goes to filters, pipes and emitters.
How to avoid: Check product and water compatibility before preparing the solution. Keep incompatible concentrated solutions separate. When they need to be applied in different operations, wash tanks, injector and network between them, according to technical guidance. Having more than one tank does not make the simultaneous injection of incompatible products safe.
3. Skipping the jar test with water from the farm
Compatibility tables consider fertilizers, but not the water you use. Water with high bicarbonate, for example, can form precipitates with the applied calcium. That's why Embrapa considers it "the most correct" to test the mixture on the farm itself.
How to avoid: Before mixing, check the manufacturer's instructions: some combinations generate heat. To evaluate the diluted solution, use the irrigation water and the proportions provided for in the application, in a transparent container. Leave it to rest for around two hours, as recommended by Embrapa, and observe whether there is turbidity or deposits at the bottom. If there is, do not inject the mixture before clarifying the cause with technical guidance. Repeat the check when changing products, suppliers or water sources. The absence of turbidity in this test does not replace water analysis or prove the compatibility of the concentrated solution in the tank.
4. Ignoring the solution's pH and electrical conductivity
pH and electrical conductivity (EC) are the two simplest readings to monitor the solution. With high pH, the risk of precipitation of calcium and magnesium carbonates increases; with excess salts, the osmotic pressure in the root zone rises. Embrapa's publication on fertigation recommends monitoring the EC and pH of the solution with commercially available instruments, and the chapter on solution preparation provides reference ranges for pH and EC that depend on the crop, water and system.
How to avoid: Use a calibrated portable pH and EC meter and record readings from the irrigation water and the diluted solution at an emitter outlet. Use these readings for routine monitoring, not to calculate a dose: the same chapter warns that EC does not accurately estimate the concentration of a fertilizer solution. The need for acidification must be assessed through water analysis, including alkalinity, and technical guidance; the pH reading alone does not determine the treatment. Preparation and operation require trained personnel and protective equipment appropriate for the chemical product. If acidification is indicated, add acid to water, never the reverse.
5. Injecting without respecting the water–fertilizer–water sequence
Turning on the injection together with the pump is a common mistake. As the lines fill and the pressure stabilizes, the fertilizer reaches the emitters closest to the head first.
Embrapa publications describe three phases: operating only with water until the sector's pressures stabilize, injecting the solution and maintaining clean water at the end long enough to remove the fertilizer from the network. One of the sources presents 15 to 20 minutes as a reference for the initial hydraulic balance. The washing time needs to consider the route from the injection point to the most distant emitter. The times must be adjusted to the system and the required irrigation depth.
How to avoid: check pressure stabilization before starting the injection and separately measure the solution displacement time, following the EC at the last emitter. Use this data to adjust the operation of each sector. Avoid prolonging washing longer than necessary, as excess water can carry nutrients below the root zone.
6. Choosing and operating an injector without calibration
Venturi, injection pump and bypass tank work in different ways. The Embrapa Solos manual describes the Venturi as simple, low cost and good precision, but with pressure loss; injection pumps as very precise, but more expensive; and the tank as cheap, but with a concentration that decreases throughout the application.
How to avoid: Choose the injector considering the area, flow rate, available pressure and desired level of control. Check the actual injection rate using the procedure indicated for the equipment. In systems that draw solution from a reservoir, the volume consumed in a given time can be measured. In the bypass tank, water enters while solution leaves; evaluate the derived flow rate and concentration throughout the application, as the tank level alone does not indicate the amount of fertilizer applied. Repeat the checks periodically, because pressure variations alter the performance of equipment such as the Venturi.
7. Neglecting filtration and protection of the water source
Poorly dissolved fertilizer, packaging impurities and precipitates formed in the tank need to be retained before reaching the emitters. Embrapa's chapter on solution preparation indicates that the injection be made at the control station, before the filter. Another precaution is to prevent the solution from returning to the well, river or reservoir when the pump turns off, as contamination of water sources is among the risks listed by Embrapa.
How to avoid: size the filter according to the water quality and type of emitter, keep cleaning up to date and include devices in the project that prevent the solution from returning to the collection. Prepare the solution in a separate container, dissolving the products well before placing them in the injection tank.
8. Using the same fertilization schedule throughout the crop cycle
The demand for nutrients changes throughout the cycle. Embrapa remembers that the need depends on the rate of nutrient absorption at different stages of the crop, and recommends, whenever possible, bringing the frequency of fertigation closer to the frequency of irrigation. For perennial crops with daily irrigation, the same source allows weekly applications.
How to avoid: assemble the program based on soil analysis, leaf analysis when applicable and the recommendation of an agronomist for the crop and region. In coffee, citrus, avocado or banana, the distribution of doses throughout the year is different from that of a short-cycle vegetable, and the calendar must reflect this.
FAQ
Does fertigation clog drippers?
It can clog when there are incompatible fertilizers, water with a high bicarbonate content, high pH or lack of washing after injection. The jar test, correct filtration and the water–fertilizer–water sequence reduce this risk. See also the errors that favor clogging of drippers.
Which fertilizer injector is best?
It depends on the system. The Venturi is simple and cheap, but it consumes pressure; injection pumps are more precise and cost more; Shunt tanks are cheap, but the concentration drops during application. The choice must consider flow, available pressure and the desired degree of automation.
Can I do sprinkler fertigation?
Yes. Embrapa cites sprinkling and localized irrigation as suitable methods for fertigation due to uniformity of application. In localized applications, the fertilizer only goes into the volume of wet soil, close to the roots.
How often should I fertigate?
There is no universal frequency. It depends on the crop, phase, soil and watering shift. Embrapa publications suggest bringing fertigation closer to the irrigation frequency, allowing weekly intervals in perennial crops.
Conclusion
Fertigation gives precision to fertilization when the system is uniform, the solution does not precipitate and the operation follows a routine. Most of the errors listed here can be resolved with simple measurements and a well-defined routine.
If you are planning to implement or review fertigation, learn about the solution automation and fertigation and talk to the Perin Irrigação team. Inform the municipality, crop, approximate size of the area and water source via WhatsApp (14) 99824-5219 or by email contato@perinirrigacao.com.br to receive technical guidance.
Sources consulted
Research carried out on 10/22/2026.
- PINTO, J.M.; SANTOS, C. R. dos. Fertigation. In: ROCHA, E. M. de M.; DRUMOND, M. A. (Ed.). Irrigated fruit growing: the producer asks, Embrapa answers. Brasília, DF: Embrapa Information Technology, 2011. p. 85–94. Accessed on: 22 Oct. 2026.
- MEDEIROS, J. F. de; SOUSA, V. F. de; MAIA, C. E.; COELHO, E. F.; MAROUELLI, W. A. Determination and preparation of fertilizer solution for fertigation. In: SOUSA, V. F. de et al. (Ed.). Irrigation and fertigation in fruit and vegetable plants. Brasília, DF: Embrapa Information Technology, 2011. chap. 8, p. 267–288. Accessed on: 22 Oct. 2026.
- TAVARES, S. R. de L. Manual for the construction and use of a simplified fertilizer injection system via irrigation water for family farming. Rio de Janeiro: Embrapa Solos, 2015 (Documents, 191). Accessed on: 22 Oct. 2026.
Additional references verified in the technical review of 10/23/2026:
- UNIVERSITY OF CALIFORNIA, AGRICULTURE AND NATURAL RESOURCES. Prevention and Mitigation. Maintenance of Microirrigation Systems. Accessed on: 23 Oct. 2026.
- ZEKRI, M. et al. Fertigation for Citrus Trees. University of Florida, IFAS Extension, HS1306. Accessed on: 23 Oct. 2026.
- PENNISI, B.; KESSLER, R. Fertilizer Injectors: Selection, Maintenance and Calibration. University of Georgia Cooperative Extension, Bulletin 1237. Revision 9 Apr. 2024. Accessed on: 23 Oct. 2026.
