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Revista mexicana de ciencias agrícolas

versão impressa ISSN 2007-0934

Rev. Mex. Cienc. Agríc vol.8 no.2 Texcoco Fev./Mar. 2017 

Investigation notes

System to program and schedule the irrigation of crops in real time

Miguel Servín Palestina1  § 

Leonardo Tijerina Chávez1 

Guillermo Medina García2 

Oscar Palacios Velez1 

Héctor Flores Magdaleno1 

1Posgrado de Hidrociencias-Colegio de Postgraduados. Carretera México-Texcoco, km 36.5. Montecillo, Texcoco, Estado de México. CP. 56230. (,,,

2Campo Experimental Zacatecas-INIFAP. (


The agricultural activity consumes more than 70% of the water available worldwide, it is considered a great consumer of water resources, this is due to the waste of water that is presented, even in technical systems since the water requirements of crops are unknown. This study focuses on irrigation scheduling, which is a technique that determines the quantity of water and the time when crops are to be irrigated, is a fundamental instrument to achieve a better use of water. It is regularly performed without technical support based solely on the users experience, which is why it is necessary to systematize and disseminate the available techniques to perform it in an appropriate way. The objective of this research was to develop an online system for irrigation users in the state of Zacatecas to estimate the water demands of crops (garlic, pepper, beans and maize) and program their irrigation in real time. This system solves the task by means of a climatic water balance and the use of climatic data obtained from the network of 36 automated agroclimatic stations distributed in the state of Zacatecas. What allows to estimate the consumption of water over time, and to determine the calendar of irrigation of the crops; the program runs via the internet and was encoded in PHP language which, along with HTML, allows you to create dynamic web sites.

Keywords: crops; evapotranspiration; water-soil; water balance; weather stations


La actividad agrícola consume más de 70% del agua disponible a nivel mundial, se considera una gran consumidora de los recursos hídricos, esto se debe al desperdicio de agua que se presenta, aun en sistemas tecnificados ya que se desconocen los requerimientos hídricos de los cultivos. Este estudio se centra en la programación del riego, que es una técnica que consiste en determinar la cantidad de agua y el momento en que han de regarse los cultivos, es un instrumento fundamental para lograr un mejor uso del agua. Regularmente se realiza sin soporte técnico con base únicamente en la experiencia de los usuarios, razón por la cual se requiere mayor sistematización y difusión de las técnicas disponibles para realizarla de una manera adecuada. El objetivo de esta investigación fue desarrollar un sistema en línea para que los usuarios de riego del estado de Zacatecas estimen las demandas de agua de los cultivos (ajo, chile, frijol y maíz) y programen sus riegos en tiempo real. Este sistema resuelve la tarea mediante un balance hídrico climático y con el uso de datos climáticos obtenidos de la red de 36 estaciones agroclimáticas automatizadas distribuidas en el estado de Zacatecas. Lo que permite estimar el consumo de agua a través del tiempo, y determinar el calendario de riegos de los cultivos; el programa se ejecuta vía internet y fue codificado en lenguaje PHP que, junto con HTML, permite crear sitios WEB dinámicos.

Palabras clave: agua-suelo; balance hídrico; cultivos; estaciones climáticas; evapotranspiración

The water is essential for the development of agricultural activity element, agriculture consumes more than 70 percent of the water available worldwide (WWAP, 2014). In Mexico 77% is used, with 6.3 million ha. Under irrigation with global efficiencies less than 50% (Sánchez et al., 2006). In the state of Zacatecas in the 2008-2009 cycle were seeded 10,890 has in irrigation (CNA, 2010). The state is located in arid and semiarid areas with high values of evapotranspiration deficit. The irrigation is the best choice for food production (Geerts and Raes, 2009). Despite its enormous importance, maldistribution and pollution make this resource is each day more scarce and expensive (Castro et al., 2008).

This is because they do not know the water requirements of crops (McCarthy et al., 2013). The importance of applying rational and quantitative techniques and methods to improve programming, design and operation of irrigation systems should be understood. Several software have been developed to support irrigation programming. Cropwat (Cropwat, 1993). DRiego Ver 1.0. (Catalán et al., 2007) Irrinet (Catalán et al., 2013) System Irriga® , SEPOR ver 2.1, which are based on the principle of conservation of mass, (Fernández, 1996). Solve the water balance in the soil, using a climatic water balance (BHC) (Botey et al., 2009).

With support from weather data automated agrometeorological stations (Smith,1991).The BHC is based not only on soil characteristics, but also on the measurement of all variables necessary for the calculation of evapotranspiration (ETo) and effective precipitation (Pe).The Penman-Monteith (Allen et al., 2006) for calculating ETo shows advantage over other models by combining the energy balance, aerodynamic factors (temperature, vapor pressure and wind speed) and drag the culture (Jensen et al., 1990). The irrigation scheduling crop normally runs without support and greater systematization and dissemination of the techniques available to do it in a proper way is required (Catalán et al., 2007). The objective of this research was to develop an online system to calculate the water demands and to schedule the irrigation of the crops (garlic, pepper, beans and maize) and to program the irrigation in real time.

The research work was carried out at the Zacatecas Experimental Field (CEZAC), Calera, Zacatecas, Mexico. (22° 54’ north latitude, 102° 39’ west longitude), at an altitude of 2 197 m, with an annual average temperature of 14.6 °C, annual mean rainfall of 416 mm, and average annual evaporation of 1 700-2 200 mm. The CEZAC manages the climate information obtained from a network with 36 automatic climatic stations strategically distributed in the state. Each has sensors to measure air temperature, relative humidity, precipitation, direction and wind speed, solar radiation and leaf moisture, every 15 minutes 24 hours a day. This network provides the state of Zacatecas with on-line and real-time meteorological information using an Adcon platform (Servin, 2015).

Method climatic water balance

According to the equation of the water balance in the soil water content of soil on a particular day, θi, is estimated based on the water content of the previous day, θi-1, as is shown in the following equation (Silva, 2001).

θi=θi-1+Ri+Pei-ETci-Di 1)

Where:Ri = irrigation of the particular day; Pi = effective precipitation of the particular day, ETci = evapotranspiration of the crop of the particular day; Di = draining a particular day it is considered “0”, the above expressed in (mm day-1).

To start with the water balance was required to determine the start of the watering period (sowing date) and lead to field capacity (soil moisture (HA) to 100%) where the values of field capacity (θCC) and point permanent wilting (θPMP) in (cm3 cm-3) are consulted depending on soil texture (Saxton et al., 1986) and Pr is the depth of exploration of the roots in cm. This will be the starting point for initiating the BHC, which subsequently accumulates the evapotranspiration water loss (ETc) of the previous day, and the amount is subtracted of effective precipitation (Pe) and irrigation (R). When the accumulated ETc is equal or greater than the critical point (θC) (ecuation 2) should be watered down and return the amount of water previously lost due to evapotranspiration. Then the amount of water, net film (Ln) to be irrigated will depend on ecuation 3.

θc= θcc-FAM100θCC-θPMP 2)

LN=θCC-θCPr 3)

Where: FAM is the maximum collapse fraction; that is, the amount of water leaving the system before applying the next irrigation.

To estimate the ETc (ecuationn 4) of crop, the program uses the specific Kc of each crop which reported Bravo et al. (2006). In order to facilitate the coding of the online system, the values were adjusted to a cubic polynomial.(Table 1). Ks is a dimensionless coefficient due to the effect of the residual water stored in the soil, since it is an irrigation zone and it is expected that the plants will not be subjected to water stress, its value is 1.

Table 1 Kc models for various crops.  

ETc=Ks*Kc*ETo 4)

With the fraction values of vegetative cycle in X axis and the crop coefficients in Y axis was made a graph for each crop, and the curve was smoothed by taking 10 freehand points to obtain the Kc model. They were fitted to a third-degree polynomial model with least squares method (SAS, 1999). The models obtained for each crop are shown in Table 1.

To obtain the ETo the program consults the climatological database of the agrometeorological station previously selected. The calculation of ETo is done daily of according to Penman-Monteith (Allen et al., 2006). The FAO Penman-Monteith method for estimating ETo is derived from the original Penman-Monteith equation and the aerodynamic and surface resistance equations, obtaining equation 5.

ETo= 0.408Rn-G+γ900T+273u2es+ea+γ1+0.34u2 5)

Where: ETo= reference evapotranspiration (mm day-1), Rn= net radiation at the culture surface (MJ m-2 day-1), G= floor heat flow (MJ m-2 day-1), T= mean air temperature at 2 m height (°C), u2= wind speed at 2 m height (m s-l), es = saturation vapor pressure (kPa), ea = actual vapor pressure (kPa), (es - ea)= vapor pressure deficit (kPa), Δ = slope of the vapor pressure curve (kPa oC-1), γ = psychrometric constant (kPa oC-1).

For the calculation of the effective precipitation (Pe), the precipitation is multiplied by a correction factor according to the climatic conditions (0.75) when this is greater than 5 mm. and if under the Pe= 0 (Serna et al., 2011). To define the time and the gross watering sheet (Lb) in mm. To be applied to the irrigation system, Lr is divided by the application efficiency (Ea), which is the relation between the water applied by the irrigation system and the water stored in the root zone, considering a range of 0.85 to 0.95 for drip irrigation and 0.45 to 0.65 for multi-door irrigation expressed in (%).

To calculate watering time (Tr) expressed in hours, necessary to calculate the hourly rate (TH) refers to that amount of water in the system serving millimeters in one hour (mm h-1), in the system of drip irrigation with belt, TH is estimated based on the emitter's expenditure in lph, (Qe), the spacing between emitters in m, (Ee), and spacing between irrigation lines in m, (ELr), (ecuation 6). The multigate for irrigation is taken into account spending entrance to the irrigation section lps (QseC) and the surface to be irrigated in ha (Sha) (ecuation 7).

THcinta=QeEe*ELr   6)

THmulti=Qsec*3.6Sha 7)

The irrigation time in hours (Tr) is the relationship between the gross irrigation sheet to be applied between the TH which indicates the number of hours to be irrigated. When watering is carried to θC to 100% of HA, and the calculation is restarted until the end of the crop cycle obtained a water balance in the soil over time.

Programming languages: For the development of the system in WEB platform PHP and HTML were used. Together they are: a very powerful programming language that allows you to create dynamic websites. This system allows to obtain in an integral way the irrigation schedule that consists of irrigation date, irrigation sheet and time of application of water to cover the water requirements of the crop. To access the system for irrigation scheduling is necessary to enter the website, which the login screen and log appears. When entering the system the map of the network of agroclimatic stations is shown, where the user will select the station closest to his property.

And followed by that will be requested input data divided into three sections 1) general and crop data; 2) soil data and irrigation criteria; and 3) data on the irrigation system (Figure 1). To facilitate the use of the program, help texts describing input and output concepts and variables are included. 1) general and crop data: season, plot name, plot coordinates, crop, date of planting or transplant, crop cycle; 2) soil data and irrigation criteria: texture, root depth, irrigation criterion: a) depletion or b) by days; 3) data on the irrigation system: this section will select the type of irrigation system a) multigates; and b) belt. When selecting the type of irrigation to use, the following data must be filled in to calculate the hourly rate: a) multigates: system expenditure, irrigation surface; and b) belt: issuer expenditure, spacing between emitters, spacing between irrigation lines, application efficiency.

Figure 1 Input data.  

The main report of this application is shown in Figure 2 beginning with the dates of planting or transplants and shows three columns with: date of irrigation. Net sheet and irrigation time.

Figure 2 Irrigation report.  

In the Figure 3 shows the water balance in the soil over time graphically from the sowing or transplant to the crop harvest.

Figure 3 Graph of soil moisture balance.  

The runs were performed for growing chili and the result was 557.5 mm (5 575 m3 ha-1) total irrigation depth throughout the cycle. Serna and Zegbe (2012) reported average volumes of water applied in three years, growing of pepper 5 010 ± 821 m3 ha-1. Khah et al. (2007) determined a total volume of 5 560 m3 ha-1 as the right to get the most business performance in drip irrigation.

The program and scheduling of irrigation in real time, gives a very accurate approach to the actual behavior of moisture in the soil, which helps in making decisions regarding when and how much watering more accurately. This online system is a useful tool for most irrigation users, who do not perform some measure of the water status of the soil or plants to decide when and how much to irrigate their crops.


This application can be used for didactic purposes by teachers and students, to better understand the theoretical principles involved in their development; as well as by researchers to help establish possible research actions oriented towards the definition of irrigation treatments or towards the improvement of the techniques used. It is recommended for the next version to add control systems and mobile communication devices via radio or MSN messaging to efficiently automate the irrigation system and obtain greater performance and profit from this application.

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Received: February 2017; Accepted: March 2017

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