# Pasture irrigation: 7 mistakes that compromise results and how to avoid them

Source page: [https://perinirrigacao.com.br/en/blog/irrigacao-de-pastagem-erros/](https://perinirrigacao.com.br/en/blog/irrigacao-de-pastagem-erros/)

Automatically translated from Portuguese. Our projects, service information and technical references relate to Brazil. Contact us to discuss your location and requirements. [Read the Portuguese original](https://perinirrigacao.com.br/blog/irrigacao-de-pastagem-erros/)

Crops

Water alone does not solve pasture. See how climate, fertilization, grazing and irrigation management factor into the result and what to check before investing.

By Team Perin Irrigação

Published in October 31, 2026 (2026-10-31)

9 min read

![Sprinkler in operation in the Perin Irrigação collection](https://perinirrigacao.com.br/assets/perin/responsive/service-sprinkler-580-aa4ae528aff2.webp)

Photograph from the Perin Irrigação collection. The image illustrates sprinkling and does not represent the pastures in the studies cited.

## Before you start

The most common errors in pasture irrigation: climate, fertilization, grazing management, choice of system, water management, water-use permit and feasibility account.

**Summary:** irrigating the pasture can increase the forage supply, but water alone does not guarantee results. Climate, fertilization, grazing and operations need to accompany the investment. See seven mistakes to avoid and what data to collect before choosing a system for your property.

## Why pasture irrigation does not always give the expected return

The review by Alencar et al., published in 2009 in *Brazilian Journal of Zootechnics*, relates pasture response to temperature, photoperiod and management. The decision requires looking at the whole picture: producing more forage does not mean, in itself, making use of this food with the herd or obtaining a financial return.

## 1. Expecting the same response year-round in every region

Water does not eliminate the limitation of cold and light. Ribeiro et al. (2009) cite the reduction in the growth of tropical forages below 16 °C. Alencar et al. discuss work in regions with average winter temperatures above 15 °C. They are references for different contexts, not universal limits for deciding when to irrigate.

In the synthesis of studies presented by Alencar et al.:

- In Governador Valadares (MG) and Gurupi (TO), dry matter production in autumn/winter corresponded, respectively, to around 76% and 80% of spring/summer production.
- In work with elephant grass in Coronel Pacheco (MG), the dry matter that could be consumed in autumn/winter corresponded to around 30% of that obtained in spring/summer.

These works had their own conditions and measures; the percentages are not a prediction for another farm.

**How to avoid:** raise the municipality’s climate history and forage response throughout the year. Plan the food supply in winter also considering the limitations that irrigation cannot solve.

## 2. Irrigation without a fertilizer plan

The studies gathered by Alencar et al. had different responses to fertilization. Some recorded an increase in dry matter with irrigation levels and doses of nitrogen and potassium; in another, increasing the nitrogen dose did not increase productivity. More fertilizer does not automatically mean more grass.

In the experiment by Ribeiro et al., the correction and fertilization of pastures were defined by the characteristics of the soil and the intended animal productivity. The irrigation results did not come from a comparison that would dispense with these precautions.

**How to avoid:** carry out a soil analysis and define fertilization with an agronomist, considering the forage, stocking capacity and costs. If there is fertigation, evaluate the splitting and distribution of doses together with water management. Our article about [common errors in fertigation](https://perinirrigacao.com.br/en/blog/fertirrigacao-erros-frequentes/) presents injection care.

## 3. Keeping grazing management unchanged after introducing irrigation

If irrigation changes the growth rate, grazing needs to follow suit. Ribeiro et al. They worked with four days of occupation and 32 days of rest, forming a cycle of 36 days. When discussing the results, the authors considered that the cycle needed to be revised and that Mombaça could have less rest during the rainy season.

The article discusses expanded leaves per tiller and interception of 95% of light by the canopy as criteria for evaluating the moment of entry. This reference does not define a height or rest interval valid for all grass.

**How to avoid:** monitor real growth and adjust rest and stocking with technical guidance. The objective is to make use of the forage produced, without letting the pasture go past its prime by following a rigid calendar.

## 4. Choosing the system before assessing the site

The 2009 review discusses semi-fixed sprinkler and center pivot, without pointing to a superior system in any condition. The 2015 Embrapa Meio-Norte material also relates the choice to soil, wind, terrain, water, labor and available resources.

Use these criteria to compare proposals:

| Criterion | What to check before choosing |
| --- | --- |
| Area and paddocks | Area format, division of sectors and grazing routine |
| Terrain, soil and wind | Pressure, infiltration and distribution of water on the ground |
| Operation | Sprinkler changes, labor and need for automation |
| Cost | Investment, energy, maintenance and current financing conditions |

Cost, financing and slope tables published in 2009 should not be used as current purchasing conditions or equipment limits. Likewise, the reference to areas smaller than 10 ha in the 2015 leaflet describes a context of application of fixed sprinkler; it is not a mandatory boundary between systems.

**How to avoid:** Start by surveying the area and available water. Then compare equipment, sizing and operating costs. The pages of [sprinkler irrigation](https://perinirrigacao.com.br/en/aspersao/) and [pasture irrigation](https://perinirrigacao.com.br/en/irrigacao-para-pastagem/) help organize this conversation with Perin.

## 5. Irrigation "by eye", without water management

Turning on the system for the same time every week ignores rain, weather and regrowth. Crop evapotranspiration (ETc = ETo × Kc) is a reference for estimating demand, explained in the article about [evapotranspiration in irrigation](https://perinirrigacao.com.br/en/blog/evapotranspiracao-na-irrigacao/). It is not an order to apply all this water: rain, soil storage and system losses are also included in the assessment.

The 2015 Embrapa leaflet presents Kc from 0.6 to 1.5 for phases of a 35-day cycle of Tanzania grass, in a table from Parnaíba (PI), from 2009. It is an experimental reference for that location and that forage, not a sequence ready to transfer to any pasture.

Two precautions complement management:

- Compare the application intensity of sprinklers with soil infiltration, to avoid surface runoff.
- Avoid excessive applications, associated in the review by Alencar et al. waste of water and energy and leaching of nutrients.

**How to avoid:** use climate data representative of the area, Kc suitable for forage and soil water monitoring. See the comparison between [tensiometer and soil moisture sensor](https://perinirrigacao.com.br/en/blog/tensiometro-ou-sensor-de-umidade-do-solo/).

## 6. Leaving water availability, permits and energy planning until later

Three points need to be included in the evaluation from the beginning:

- **Water quality and quantity:** check whether the source meets the demand and what treatments the system requires. The article about [water analysis for irrigation](https://perinirrigacao.com.br/en/blog/analise-de-agua-para-irrigacao/) explains the collection and parameters to discuss with the laboratory.
- **Regularization of use:** Law 9,433/1997 provides for water-use permits for capturing surface water and extracting underground water for final consumption or production processes. Uses considered insignificant may not require a water-use permit, according to regulations, but this does not mean that all registration or declarations are not required. ANA advises checking the competence of the managing body; Groundwater is regulated by the states or the Federal District. Consult the person responsible for the water source before installing the catchment.
- **Energy:** pumping is part of the operating cost. Flow, head and operating time need to be evaluated together. See [how to choose the pump for irrigation](https://perinirrigacao.com.br/en/blog/bomba-para-irrigacao-como-escolher/). Rates and possible discounts must be confirmed with the distributor according to current rules.

## 7. Deciding without calculating your property

In Campos dos Goytacazes (RJ), in the 2002–2003 experiment published by Ribeiro et al. in 2009, irrigation increased the availability of **total dry matter** 48% for Mombasa and 23% for Napier in the dry season. In the rainy season, the increases were 29% and 15%, respectively. The minimum monthly temperatures recorded in the study did not fall below 15.5 °C.

These are results of that experiment, not guaranteed increases in animal production or revenue. Even with the response in forage, the authors pointed out the need for an economic assessment before concluding on viability.

**How to avoid:** calculate the farm's calculations: investment, energy, maintenance, labor, fertilization, expected response to the local climate and the herd's ability to use the forage. Compare with other ways of planning feeding, such as silage, hay or stocking adjustment.

## FAQ

**Is it worth irrigating pastures during the rainy season?** There may be a response in periods of water deficit. Ribeiro et al. observed an increase in total dry matter also in the rainy season, under the conditions of the experiment. This does not prove economic viability in the entire area nor does it justify irrigating when the soil already has enough water.

**Which grass responds best to irrigation?** There is no single answer. The review by Alencar et al. reports good performance of xaraés in an experiment in the East of Minas, among six grasses evaluated. Climate, soil, fertilization and management change this comparison.

## Conclusion

Before choosing equipment, confirm whether the climate, water, soil, fertilization and grazing support the project. Then, compare the investment with the cost of operating and how the herd will use the forage. This analysis helps define where irrigation can contribute and which limitations require another solution.

If you are considering irrigating pastures, the Perin Irrigação team can help analyze the technical conditions in your area. Send municipality, forage, approximate area and water source via WhatsApp [(14) 99824-5219](https://wa.me/5514998245219) or by email contato@perinirrigacao.com.br.

## Sources consulted

Research carried out on 10/31/2026. Experimental results and historical comparisons were kept in their contexts; do not represent a prediction for the reader's property.

- [ALENCAR, C. A. B. et al. Pasture irrigation: current affairs and recommendations for use and management. *Brazilian Journal of Zootechnics*, v. 38, p. 98-108, 2009 (special supplement).](https://www.alice.cnptia.embrapa.br/alice/bitstream/doc/696924/1/Irrigacao-de-pastagem-atualidade-e-recomendacoes-para-uso-e-manejo.pdf)
- [RIBEIRO, E. G. et al. Influence of irrigation, in dry and rainy seasons, on the production and chemical composition of napier and mombaça grasses in an intermittent stocking system. *Brazilian Journal of Zootechnics*, v. 38, no. 8, p. 1432-1442, 2009.](https://www.alice.cnptia.embrapa.br/alice/bitstream/doc/696993/1/Influencia-da-irrigacao-nas-epocas-seca-e-chuvosa-na-producao-e-composicao-quimica-dos-capins-napier-e-mombaca.pdf)
- [RODRIGUES, B. H. N.; SANTOS, F. J. S.; MAGALHÃES, J. A. *Pasture irrigation: systems and management*. Teresina: Embrapa Meio-Norte, 2015.](https://www.infoteca.cnptia.embrapa.br/infoteca/bitstream/doc/1039758/1/braz2.pdf)
- [BRAZIL. Law No. 9,433, of January 8, 1997, updated text, arts. 12 and 14. Chamber of Deputies.](https://www2.camara.leg.br/legin/fed/lei/1997/lei-9433-8-janeiro-1997-374778-normaatualizada-pl.html)
- [NATIONAL WATER AND BASIC SANITATION AGENCY (ANA). Frequently asked questions: water-use permitting of rights to use water resources.](https://www.gov.br/ana/pt-br/acesso-a-informacao/perguntas-frequentes)

## From knowledge to your project.

In agricultural production or green areas, the project starts with the conditions of your area and the water supply. Tell Perin what you need to irrigate.

[Request quote](https://perinirrigacao.com.br/en/#contato)[Chat on WhatsApp](https://wa.me/5514998245219?text=Hello%21+I+want+to+talk+about+an+irrigation+project.)