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Transfer of irrigation scheduling technology in Mexico
Agricultural Water Management 40 (1999) 333±339
Transfer of irrigation scheduling technology in Mexico Pedroza Hector QuinÄonesa,*, Helene Unlandb, Waldo Ojedab, Ernesto Sifuentesb a
CEMAGREF, 361 rue J.F Breton BP 5095, 34033, Monpellier, France b IMTA, Paseo Cuahnuahuac 8532, 62550 Jiutepec, Mor, Mexico
Abstract In Mexico most of the agricultural production originates from large irrigation districts in the northern part of the country. This region is characterized by its semiarid desert climate with a winter rainy season dominated by frontal storms, and a summer monsoon season dominated by highly localized convective storms, yielding most of the annual precipitation. Essentially all irrigation needs must be met by surface water stored in various reservoirs. Precipitation is, therefore, the most important limiting factor in Mexico's agricultural production. Traditionally, long-time averages of statistical climate data from few and widely-spaced weather stations were used to determine frequency and amount of water applied, and the algorithms employed usually did not consider the effects of great spatial climate variability and plant physiology. In the past five years, great parts of Mexico, especially in the North, have been affected by severe water shortages resulting from insufficient precipitation (perhaps related to the `El NinÄo' phenomenon), combined with inefficient water resources management. Irrigation districts increasingly have to deal with the considerable uncertainty in water resources availability as a limiting factor in the decision making process. In order to address these irrigation water shortages, the Mexican National Water Commission and the Mexican Water Resources Institute are introducing new technologies using agrometeorological networks for more efficient, real-time irrigation scheduling in the main irrigation districts of Mexico. Validation plots established in one particular irrigation district (Carrizo Valley, Sinaloa), demonstrate water savings in the order of at least 20% without any appreciable decrease in crop yields. # 1999 Elsevier Science B.V. All rights reserved. Keywords: Technology transfer; Irrigation scheduling; Agrometeorological networks; Irrigation ef®ciency
* Corresponding author. Tel.: +33-4-67-04-63-04; fax: +33-4-67-04-63-00; e-mail: [email protected] 0378-3774/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 8 - 3 7 7 4 ( 9 9 ) 0 0 0 0 7 - 4
334
P.H. QuinÄones et al. / Agricultural Water Management 40 (1999) 333±339
1. Introduction Determining crop water demands has been an on-going problem for parcel- and district-level irrigation scheduling (Jensen et al., 1990; D'Urso and Santini, 1996). The continuing progress in the technical development of agrometeorological sensors and controls is directly proportional to advancements in the development of less expensive, but more exacting electronic components used for measuring quantities to define the various components of the soil±water±plant±atmosphere system, which is one of the most important factors in the agricultural decision making process. One example of these technical innovations is the increased use of automated weather stations (AWS) as an essential tool to determine the reference crop evapotranspiration (ET0) on an almost `continuous' time scale (Campbell Scientific Inc., 1993; Elliot et al., 1994). A great number of sensors and controls available today allow farmers to automatize their operations and monitor crop water stress-related variables like matric potential, soil water content and the depth of the water table. The problem of diminishing water supplies in semi-arid regions like northern Sinaloa has been increasing, especially in the past few years due to recurring, but non-cyclical droughts. To mitigate this detrimental impact on agricultural zones, the Irrigation and Drainage Division of the Mexican Water Resources Institute (IMTA), in collaboration with the National Water Commission (CNA) and the Irrigation District of the Carrizo Valley's Users Association, initiated in 1993 the project called `Real-Time Irrigation Scheduling System' in the Carrizo Valley, Sinaloa, with the installation of two AWS which are capable of measuring meteorological parameters associated with plant water stress in an `almost' continuous fashion. This system, Fig. 1, manipulates a suite of databases, including information about plant physiology, soil, weather, water distribution networks and a list of the users, to calculate the irrigation water needs for each single plot which are subsequently integrated to the district level. For the Fall/Winter 1995±1996 planting cycle, irrigation water applications in four representative samples (143 ha) of maize and wheat in the Carrizo Valley Irrigation District were reduced by more than 20% without reduction in crop yields. Due to the encouraging results, the system is now being transferred to other important irrigation districts of Mexico, including Altar Pitiquito, Sonora, Santo Domingo Valley, Baja California Sur, and `del Fuerte' Valley, Sinaloa. A total of 17 AWS installed in these three districts is a part of the mexican national Agrometeorological weather station Network, RAN (Ojeda et al., 1997), with data dissemination over the Internet. The irrigation forecasting system is expected to be operational in the `del Fuerte' Valley Irrigation District, utilizing its network of 14 AWS covering an area of more than 220 000 ha in 13 irrigation sub-districts. Installation is also under way in the Santo Domingo Valley irrigation district, and other districts should follow in the coming years. 2. Methods The real-time irrigation forecasting system integrates plant, soil, weather, and water distribution network (Figs. 1 and 2), related components to schedule irrigation water
P.H. QuinÄones et al. / Agricultural Water Management 40 (1999) 333±339
335
Fig. 1. Principle components of Real-Time Irrigation Forecasting System.
applications on a plot-by-plot basis as well as allowing for easy upscaling to the district level. This system has been implemented in two irrigation districts: the Carrizo Valley Irrigation District and the `del Fuerte' Valley irrigation District. In the Fall/Winter 1996±1997 season, eight field-plots of maize and wheat were selected in the Carrizo Valley, sinaloa to calibrate the real-time irrigation forecasting system. System implementation on the district-wide level is being achieved by transferring the prototype system developed in the Carrizo Valley with adaptations to the local conditions found in the `del Fuerte' Valley Irrigation district. A plan for a typical weather station network as commonly used in the National Agrometeorological Network (RAN) is shown in Fig. 2 below. The biggest network of the RAN to date is located in the `del Fuerte' Valley Irrigation District and includes 14 AWS and six repeaters. As of October 1997, 30 users connected to the network server are able to download climate data from the system. Based on climate data from these weather stations, reference crop evapotranspiration is calculated, which is indispensable for the proper operation of the real-time irrigation forecasting system. 2.1. The carrizo valley irrigation district The project was initiated by the Mexican Water Resources Institute (IMTA) with the installation of two AWS (representing the seashore and interior lands conditions,
336
P.H. QuinÄones et al. / Agricultural Water Management 40 (1999) 333±339
Fig. 2. Typical weather station network in the RAN.
respectively) in the Carrizo Valley, Sinaloa during the year of 1995. The parameters measured each 10 s by the AWS are temperature, relative humidity, radiation, speed and direction of wind and rainfall. The year 1996 was dedicated mainly to building the system databases and defining the principal algorithms (using the variables described in the next paragraph), necessary for calculating the water balance. At this point in time, the system is in the process of being validated and calibrated (the water balance, as well as the crop growing, are continuously measured and compared with the system estimations) in the four sub-districts of the Carrizo Valley, covering a cropped area of 44 000 ha and including a total of 4000 users in the association. The system allows for irrigation water routing during all parts of the agricultural cycle and throughout the water distribution system from the reservoir to the main- and side channels down to each individual plot. Each day for each plot the soil and plant conditions are calculated and the results are integrated in the space and time.
P.H. QuinÄones et al. / Agricultural Water Management 40 (1999) 333±339
337
As a part of the project, experiments were designed to determine the system requirements including dynamic rooting depth (Pr), crop factors (Kc) maximum permissible soil moisture deficit ( f ), phenological phases for each crop, and soil moisture data for all field plots in the district. As of October 1997 the system has been applied to 80 plots of participating users throughout the district. 2.2. The `del Fuerte' valley irrigation district In the `del Fuerte' Valley Irrigation District, the project was initiated, lead by the IMTA in direct collaboration with the CNA and the `del Fuerte' Valley Irrigation District. Due to its great areal extent (220 000 ha) and the existence of many different micro-climate zones, a network of 14 AWS was installed with six radio-repeaters in strategic locations to improve data transfer from the stations to a centrally located radio base station, facilitating adequate spatial coverage of the district area with the weather stations. A computer connected to a modem and with access to a direct phone line makes the meteorological data available on a 24 h basis practically in real-time, as data are downloaded automatically every 15 min from all the stations in the network. At this time, data are being made available to the users in the main offices of the 13 sub-districts, as well as to several independent organizations and farmers. Data available for downloading over modem include air temperature, relative humidity, solar radiation, precipitation, wind speed and direction, leaf wetness, as well as reference-crop evapotranspiration calculated by the Penman-Monteith method (Allen et al., 1989; Smith, 1990). Station data are also periodically updated and made available in hypertext format on the systems' web page (http://www.chapingo.mx/RAN). In the summer 1997 agricultural season, parameter calibration was undertaken in three sub-districts, with work continuing into the Fall/Winter 1997±1998 season. Two sample plots were selected in each one of the sub-districts to determine the following crop parameters crop factor (Kc), phenological phases, dynamic rooting depth (Pr) and maximum permissible soil moisture deficit (f), using the methodology already established in previous field trails in the Carrizo Valley. For this calibration, the concept of `growing degree days' (GDD) (Snyder, 1985; Scherer et al., 1990; Slack et al., 1996) is being employed, using the number of GDD accumulated to date, rather than the number of days since seeding, to allow for easy transfer of calibration results to conditions different from those prevailing when and where the calibration was undertaken. 3. Results and discussion Tables 1 and Fig. 2 show results for wheat and maize crops, respectively, comparing plots managed under the new real-time irrigation forecasting system, to plots using traditional irrigation scheduling methods. For the Fall/Winter 1996±1997 season, the four wheat plots in the Carrizo Valley which participated in the new system, when compared to those under traditional irrigation management, showed 26% higher crop yields, a 21% lower irrigation water use, and a 59% higher water productivity which can most probably be attributed to the greater precision in the timing and volume of irrigation water applied,
338
P.H. QuinÄones et al. / Agricultural Water Management 40 (1999) 333±339
Table 1 Crop productivity and water consumption for winter wheat in four sample plots employing the new real-time irrigation scheduling system as compared to the average of five representative plots using conventional irrigation scheduling methods (1996±1997 season, Carrizo Valley Irrigation District, Mexico) Parameter
Total crop area (ha)
Average crop yield (kg/ha)
Average depth of Average water water applied (cm/ha) productivity (kg/m3)
Sample plots, real-time irrigation scheduling Reference plots, conventional irrigation scheduling method Percent difference
84
5502
47.4
1.16
41.5
4363
59.7
0.73
±
26.1a
ÿ20.6b
58.9
a
Derived from databases of depths of irrigation water applied in the irrigation sub-districts. From average of nine estimates Fall/Winter 1996±1997 (source: personal communication with SAGAR section heads, technicians and from samples of producers). b
which also resulted in a reduction in soil-water losses due to percolation. For the four maize plots which participated in the real-time irrigation scheduling system, average crop yields and water productivity during the Fall/Winter 1996±1997 season were greater by 12% and 18%, respectively, while the depth of water applied was 6% less than in the plots employing traditional irrigation scheduling methods (Table 2). It should be mentioned that during the above described agricultural cycle, the potential level of savings for the participating plots were not fully realized, since `participating' users irrigated at the correct time according to model predictions, but applied much higher volumes of water than what should have been sufficient according to system calculations, that is, the system predicted that the average depth of water applied should have been 42 and 55 cm/ha for what and maize, respectively. However, the depths of water actually applied to these crops were, on the average, 47.3 and 74.8 cm/ha, for wheat and maize, respectively (see Tables 1 and 2), effectively resulting in water applications 13% and 36% greater than predicted by the model. In both cases (for wheat and maize), the water productivity increased in the plots using the real-time forecasting system. While there were no significant irrigation water savings observed for the maize plots, yields still improved, which can be attributed to the fact that Table 2 Crop productivity and water consumption for four maize sample plots employing the new real-time irrigation scheduling system as compared to the average of five representative plots using conventional irrigation scheduling methods (1996±1997 season, Carrizo Valley Irrigation District, Mexico) Parameter
Total crop area (ha)
Average crop yield (kg/ha)
Average depth of Average water water applied (cm/ha) productivity (kg/m3)
Sample plots, real-time irrigation scheduling Reference plots, conventional irrigation scheduling method Percent difference
59
8758
74.8
1.17
43
7820
79.2
0.99
ÿ5.6b
18.18
a
±
11.99a
Derived from databases of depths of irrigation water applied in the irrigation sub-districts. From average of nine estimates Fall/Winter 1996±1997 (source: personal communication with SAGAR section heads, technicians and from samples of producers). b
P.H. QuinÄones et al. / Agricultural Water Management 40 (1999) 333±339
339
the new system allows for more precise irrigation applications resulting the better plant development than what is possible using the traditional methods. 4. Conclusions The implementation of this real-time irrigation scheduling system in the Valley of Carrizo has resulted in a significant improvement in water use efficiency due to the careful field calibration of the model parameters. Validation plots proved to be an excellent tool to test the system efficiency during the process of transferring this technology to the irrigation districts of northern Sinaloa, Mexico. Study results show that water savings on the order of 20% can be expected without appreciable reduction in conventional yields. The use of computational models which manipulate databases to estimate plant water requirements, as employed in the real-time irrigation forecasting system described in this study, presents an effective method for determining the quantity and timing of irrigation water applications which should results in optimal crop yields and efficient water use as well as allowing for more efficient applications of agrochemicals. Due to the encouraging results in the Carrizo Valley Irrigation District, the Mexican government is supporting projects to expand this program by transferring this new technology to three other important irrigation districts in northern Mexico, specifically Altar-Pitiquito, Sonora; Santo Domingo Valley, Baja California Sur; and `del Fuerte' Valley, sinaloa ± the latter with a total cropped surface of more than 220 000 ha. References Allen, R.G., Jensen, M.E., Wright, J.L., Burman, R.D., 1989. Operational estimates of reference evapotranspiration. Agron. J. 81, 650±662. Campbell Scientific Inc. 1993. On-line measurement of potential evapotranspiration with the Campbell scientific automated weather station. Information pamphlet, Campbell Scientific Inc., 815W, 18000N, Logan, UT, USA, 23 pp. D'Urso, G.D., Santini, A., 1996. A remote sensing and modeling integrated approach for the management of irrigation distribution system. Evaporation and Irrigation Scheduling. Proc. Int. Conf. 3±6 November, San Antonio, TX, USA. Elliot, R.L., Brock, F.V., Stone, M.L., y Harp, S.L., 1994. Configuration decision for an automated weather station network. Appl. Eng. Agric. 10(1), 45±51. Jensen, M.E., Burman, R.D., Allen, R.G., 1990. Evapotranspiration and irrigation water requirements. ASCE manual no 171. Ojeda, W.H., Unland, O., Lemus, E., Fitz, Espinoza, T., Verdugo, L., 1997. La Red AgrometeoroloÂgica Nacional, VII Congreso Nacional de IrrigacioÂn, ANEI, Hermosillo, Sonora, 1±44 a 1±48. Scherer, T.F., Slack, D.F., y Clark, L.J., 1990. Near real time irrigation scheduling using heat unit based crop coefficients. Proc. National Conf. Irrigation and Drainage. ASCE, pp. 544±551. Slack, D.C., Martin, E.C., Sheta, A.E., Fox, F., Clark, L.J., Ashley, R.O.C., 1996. Crop coefficients for climatic variability with growing-degree days. In: Proc. Int. Conf. ASAE. Evapotranspiration and Irrigation Scheduling. pp. 892±898. Smith, M., 1990. Expert consultation on revision of FAO methodologies for crop water requirements. FAO Report, Land and Water Dev. Div., 55 pp. Snyder, R.L., 1985. Hand calculating degree days. Agric. Forest Meteorol. 35, 353±358.
Transfer of irrigation scheduling technology in Mexico Pedroza Hector QuinÄonesa,*, Helene Unlandb, Waldo Ojedab, Ernesto Sifuentesb a
CEMAGREF, 361 rue J.F Breton BP 5095, 34033, Monpellier, France b IMTA, Paseo Cuahnuahuac 8532, 62550 Jiutepec, Mor, Mexico
Abstract In Mexico most of the agricultural production originates from large irrigation districts in the northern part of the country. This region is characterized by its semiarid desert climate with a winter rainy season dominated by frontal storms, and a summer monsoon season dominated by highly localized convective storms, yielding most of the annual precipitation. Essentially all irrigation needs must be met by surface water stored in various reservoirs. Precipitation is, therefore, the most important limiting factor in Mexico's agricultural production. Traditionally, long-time averages of statistical climate data from few and widely-spaced weather stations were used to determine frequency and amount of water applied, and the algorithms employed usually did not consider the effects of great spatial climate variability and plant physiology. In the past five years, great parts of Mexico, especially in the North, have been affected by severe water shortages resulting from insufficient precipitation (perhaps related to the `El NinÄo' phenomenon), combined with inefficient water resources management. Irrigation districts increasingly have to deal with the considerable uncertainty in water resources availability as a limiting factor in the decision making process. In order to address these irrigation water shortages, the Mexican National Water Commission and the Mexican Water Resources Institute are introducing new technologies using agrometeorological networks for more efficient, real-time irrigation scheduling in the main irrigation districts of Mexico. Validation plots established in one particular irrigation district (Carrizo Valley, Sinaloa), demonstrate water savings in the order of at least 20% without any appreciable decrease in crop yields. # 1999 Elsevier Science B.V. All rights reserved. Keywords: Technology transfer; Irrigation scheduling; Agrometeorological networks; Irrigation ef®ciency
* Corresponding author. Tel.: +33-4-67-04-63-04; fax: +33-4-67-04-63-00; e-mail: [email protected] 0378-3774/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 8 - 3 7 7 4 ( 9 9 ) 0 0 0 0 7 - 4
334
P.H. QuinÄones et al. / Agricultural Water Management 40 (1999) 333±339
1. Introduction Determining crop water demands has been an on-going problem for parcel- and district-level irrigation scheduling (Jensen et al., 1990; D'Urso and Santini, 1996). The continuing progress in the technical development of agrometeorological sensors and controls is directly proportional to advancements in the development of less expensive, but more exacting electronic components used for measuring quantities to define the various components of the soil±water±plant±atmosphere system, which is one of the most important factors in the agricultural decision making process. One example of these technical innovations is the increased use of automated weather stations (AWS) as an essential tool to determine the reference crop evapotranspiration (ET0) on an almost `continuous' time scale (Campbell Scientific Inc., 1993; Elliot et al., 1994). A great number of sensors and controls available today allow farmers to automatize their operations and monitor crop water stress-related variables like matric potential, soil water content and the depth of the water table. The problem of diminishing water supplies in semi-arid regions like northern Sinaloa has been increasing, especially in the past few years due to recurring, but non-cyclical droughts. To mitigate this detrimental impact on agricultural zones, the Irrigation and Drainage Division of the Mexican Water Resources Institute (IMTA), in collaboration with the National Water Commission (CNA) and the Irrigation District of the Carrizo Valley's Users Association, initiated in 1993 the project called `Real-Time Irrigation Scheduling System' in the Carrizo Valley, Sinaloa, with the installation of two AWS which are capable of measuring meteorological parameters associated with plant water stress in an `almost' continuous fashion. This system, Fig. 1, manipulates a suite of databases, including information about plant physiology, soil, weather, water distribution networks and a list of the users, to calculate the irrigation water needs for each single plot which are subsequently integrated to the district level. For the Fall/Winter 1995±1996 planting cycle, irrigation water applications in four representative samples (143 ha) of maize and wheat in the Carrizo Valley Irrigation District were reduced by more than 20% without reduction in crop yields. Due to the encouraging results, the system is now being transferred to other important irrigation districts of Mexico, including Altar Pitiquito, Sonora, Santo Domingo Valley, Baja California Sur, and `del Fuerte' Valley, Sinaloa. A total of 17 AWS installed in these three districts is a part of the mexican national Agrometeorological weather station Network, RAN (Ojeda et al., 1997), with data dissemination over the Internet. The irrigation forecasting system is expected to be operational in the `del Fuerte' Valley Irrigation District, utilizing its network of 14 AWS covering an area of more than 220 000 ha in 13 irrigation sub-districts. Installation is also under way in the Santo Domingo Valley irrigation district, and other districts should follow in the coming years. 2. Methods The real-time irrigation forecasting system integrates plant, soil, weather, and water distribution network (Figs. 1 and 2), related components to schedule irrigation water
P.H. QuinÄones et al. / Agricultural Water Management 40 (1999) 333±339
335
Fig. 1. Principle components of Real-Time Irrigation Forecasting System.
applications on a plot-by-plot basis as well as allowing for easy upscaling to the district level. This system has been implemented in two irrigation districts: the Carrizo Valley Irrigation District and the `del Fuerte' Valley irrigation District. In the Fall/Winter 1996±1997 season, eight field-plots of maize and wheat were selected in the Carrizo Valley, sinaloa to calibrate the real-time irrigation forecasting system. System implementation on the district-wide level is being achieved by transferring the prototype system developed in the Carrizo Valley with adaptations to the local conditions found in the `del Fuerte' Valley Irrigation district. A plan for a typical weather station network as commonly used in the National Agrometeorological Network (RAN) is shown in Fig. 2 below. The biggest network of the RAN to date is located in the `del Fuerte' Valley Irrigation District and includes 14 AWS and six repeaters. As of October 1997, 30 users connected to the network server are able to download climate data from the system. Based on climate data from these weather stations, reference crop evapotranspiration is calculated, which is indispensable for the proper operation of the real-time irrigation forecasting system. 2.1. The carrizo valley irrigation district The project was initiated by the Mexican Water Resources Institute (IMTA) with the installation of two AWS (representing the seashore and interior lands conditions,
336
P.H. QuinÄones et al. / Agricultural Water Management 40 (1999) 333±339
Fig. 2. Typical weather station network in the RAN.
respectively) in the Carrizo Valley, Sinaloa during the year of 1995. The parameters measured each 10 s by the AWS are temperature, relative humidity, radiation, speed and direction of wind and rainfall. The year 1996 was dedicated mainly to building the system databases and defining the principal algorithms (using the variables described in the next paragraph), necessary for calculating the water balance. At this point in time, the system is in the process of being validated and calibrated (the water balance, as well as the crop growing, are continuously measured and compared with the system estimations) in the four sub-districts of the Carrizo Valley, covering a cropped area of 44 000 ha and including a total of 4000 users in the association. The system allows for irrigation water routing during all parts of the agricultural cycle and throughout the water distribution system from the reservoir to the main- and side channels down to each individual plot. Each day for each plot the soil and plant conditions are calculated and the results are integrated in the space and time.
P.H. QuinÄones et al. / Agricultural Water Management 40 (1999) 333±339
337
As a part of the project, experiments were designed to determine the system requirements including dynamic rooting depth (Pr), crop factors (Kc) maximum permissible soil moisture deficit ( f ), phenological phases for each crop, and soil moisture data for all field plots in the district. As of October 1997 the system has been applied to 80 plots of participating users throughout the district. 2.2. The `del Fuerte' valley irrigation district In the `del Fuerte' Valley Irrigation District, the project was initiated, lead by the IMTA in direct collaboration with the CNA and the `del Fuerte' Valley Irrigation District. Due to its great areal extent (220 000 ha) and the existence of many different micro-climate zones, a network of 14 AWS was installed with six radio-repeaters in strategic locations to improve data transfer from the stations to a centrally located radio base station, facilitating adequate spatial coverage of the district area with the weather stations. A computer connected to a modem and with access to a direct phone line makes the meteorological data available on a 24 h basis practically in real-time, as data are downloaded automatically every 15 min from all the stations in the network. At this time, data are being made available to the users in the main offices of the 13 sub-districts, as well as to several independent organizations and farmers. Data available for downloading over modem include air temperature, relative humidity, solar radiation, precipitation, wind speed and direction, leaf wetness, as well as reference-crop evapotranspiration calculated by the Penman-Monteith method (Allen et al., 1989; Smith, 1990). Station data are also periodically updated and made available in hypertext format on the systems' web page (http://www.chapingo.mx/RAN). In the summer 1997 agricultural season, parameter calibration was undertaken in three sub-districts, with work continuing into the Fall/Winter 1997±1998 season. Two sample plots were selected in each one of the sub-districts to determine the following crop parameters crop factor (Kc), phenological phases, dynamic rooting depth (Pr) and maximum permissible soil moisture deficit (f), using the methodology already established in previous field trails in the Carrizo Valley. For this calibration, the concept of `growing degree days' (GDD) (Snyder, 1985; Scherer et al., 1990; Slack et al., 1996) is being employed, using the number of GDD accumulated to date, rather than the number of days since seeding, to allow for easy transfer of calibration results to conditions different from those prevailing when and where the calibration was undertaken. 3. Results and discussion Tables 1 and Fig. 2 show results for wheat and maize crops, respectively, comparing plots managed under the new real-time irrigation forecasting system, to plots using traditional irrigation scheduling methods. For the Fall/Winter 1996±1997 season, the four wheat plots in the Carrizo Valley which participated in the new system, when compared to those under traditional irrigation management, showed 26% higher crop yields, a 21% lower irrigation water use, and a 59% higher water productivity which can most probably be attributed to the greater precision in the timing and volume of irrigation water applied,
338
P.H. QuinÄones et al. / Agricultural Water Management 40 (1999) 333±339
Table 1 Crop productivity and water consumption for winter wheat in four sample plots employing the new real-time irrigation scheduling system as compared to the average of five representative plots using conventional irrigation scheduling methods (1996±1997 season, Carrizo Valley Irrigation District, Mexico) Parameter
Total crop area (ha)
Average crop yield (kg/ha)
Average depth of Average water water applied (cm/ha) productivity (kg/m3)
Sample plots, real-time irrigation scheduling Reference plots, conventional irrigation scheduling method Percent difference
84
5502
47.4
1.16
41.5
4363
59.7
0.73
±
26.1a
ÿ20.6b
58.9
a
Derived from databases of depths of irrigation water applied in the irrigation sub-districts. From average of nine estimates Fall/Winter 1996±1997 (source: personal communication with SAGAR section heads, technicians and from samples of producers). b
which also resulted in a reduction in soil-water losses due to percolation. For the four maize plots which participated in the real-time irrigation scheduling system, average crop yields and water productivity during the Fall/Winter 1996±1997 season were greater by 12% and 18%, respectively, while the depth of water applied was 6% less than in the plots employing traditional irrigation scheduling methods (Table 2). It should be mentioned that during the above described agricultural cycle, the potential level of savings for the participating plots were not fully realized, since `participating' users irrigated at the correct time according to model predictions, but applied much higher volumes of water than what should have been sufficient according to system calculations, that is, the system predicted that the average depth of water applied should have been 42 and 55 cm/ha for what and maize, respectively. However, the depths of water actually applied to these crops were, on the average, 47.3 and 74.8 cm/ha, for wheat and maize, respectively (see Tables 1 and 2), effectively resulting in water applications 13% and 36% greater than predicted by the model. In both cases (for wheat and maize), the water productivity increased in the plots using the real-time forecasting system. While there were no significant irrigation water savings observed for the maize plots, yields still improved, which can be attributed to the fact that Table 2 Crop productivity and water consumption for four maize sample plots employing the new real-time irrigation scheduling system as compared to the average of five representative plots using conventional irrigation scheduling methods (1996±1997 season, Carrizo Valley Irrigation District, Mexico) Parameter
Total crop area (ha)
Average crop yield (kg/ha)
Average depth of Average water water applied (cm/ha) productivity (kg/m3)
Sample plots, real-time irrigation scheduling Reference plots, conventional irrigation scheduling method Percent difference
59
8758
74.8
1.17
43
7820
79.2
0.99
ÿ5.6b
18.18
a
±
11.99a
Derived from databases of depths of irrigation water applied in the irrigation sub-districts. From average of nine estimates Fall/Winter 1996±1997 (source: personal communication with SAGAR section heads, technicians and from samples of producers). b
P.H. QuinÄones et al. / Agricultural Water Management 40 (1999) 333±339
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the new system allows for more precise irrigation applications resulting the better plant development than what is possible using the traditional methods. 4. Conclusions The implementation of this real-time irrigation scheduling system in the Valley of Carrizo has resulted in a significant improvement in water use efficiency due to the careful field calibration of the model parameters. Validation plots proved to be an excellent tool to test the system efficiency during the process of transferring this technology to the irrigation districts of northern Sinaloa, Mexico. Study results show that water savings on the order of 20% can be expected without appreciable reduction in conventional yields. The use of computational models which manipulate databases to estimate plant water requirements, as employed in the real-time irrigation forecasting system described in this study, presents an effective method for determining the quantity and timing of irrigation water applications which should results in optimal crop yields and efficient water use as well as allowing for more efficient applications of agrochemicals. Due to the encouraging results in the Carrizo Valley Irrigation District, the Mexican government is supporting projects to expand this program by transferring this new technology to three other important irrigation districts in northern Mexico, specifically Altar-Pitiquito, Sonora; Santo Domingo Valley, Baja California Sur; and `del Fuerte' Valley, sinaloa ± the latter with a total cropped surface of more than 220 000 ha. References Allen, R.G., Jensen, M.E., Wright, J.L., Burman, R.D., 1989. Operational estimates of reference evapotranspiration. Agron. J. 81, 650±662. Campbell Scientific Inc. 1993. On-line measurement of potential evapotranspiration with the Campbell scientific automated weather station. Information pamphlet, Campbell Scientific Inc., 815W, 18000N, Logan, UT, USA, 23 pp. D'Urso, G.D., Santini, A., 1996. A remote sensing and modeling integrated approach for the management of irrigation distribution system. Evaporation and Irrigation Scheduling. Proc. Int. Conf. 3±6 November, San Antonio, TX, USA. Elliot, R.L., Brock, F.V., Stone, M.L., y Harp, S.L., 1994. Configuration decision for an automated weather station network. Appl. Eng. Agric. 10(1), 45±51. Jensen, M.E., Burman, R.D., Allen, R.G., 1990. Evapotranspiration and irrigation water requirements. ASCE manual no 171. Ojeda, W.H., Unland, O., Lemus, E., Fitz, Espinoza, T., Verdugo, L., 1997. La Red AgrometeoroloÂgica Nacional, VII Congreso Nacional de IrrigacioÂn, ANEI, Hermosillo, Sonora, 1±44 a 1±48. Scherer, T.F., Slack, D.F., y Clark, L.J., 1990. Near real time irrigation scheduling using heat unit based crop coefficients. Proc. National Conf. Irrigation and Drainage. ASCE, pp. 544±551. Slack, D.C., Martin, E.C., Sheta, A.E., Fox, F., Clark, L.J., Ashley, R.O.C., 1996. Crop coefficients for climatic variability with growing-degree days. In: Proc. Int. Conf. ASAE. Evapotranspiration and Irrigation Scheduling. pp. 892±898. Smith, M., 1990. Expert consultation on revision of FAO methodologies for crop water requirements. FAO Report, Land and Water Dev. Div., 55 pp. Snyder, R.L., 1985. Hand calculating degree days. Agric. Forest Meteorol. 35, 353±358.