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Terra Latinoamericana E-ISSN: 2395-8030 [email protected] Sociedad Mexicana de la Ciencia del Suelo, A.C. México Castellanos, J. Z.; Ortega Guerrero, A.; Grajeda, O. A.; Vázquez Alarcón, A.; Villalobos, S.; Muñoz Ramos, J. J.; Zamudio, B.; Martínez, J. G.; Hurtado, B.; Vargas, P.; Enríquez, S. A. Changes in the quality of groundwater for agricultural use in Guanajuato Terra Latinoamericana, vol. 20, núm. 2, abril-junio, 2002, pp. 161--170 Sociedad Mexicana de la Ciencia del Suelo, A.C. Chapingo, México Available in: http://www.redalyc.org/articulo.oa?id=57320209 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative CASTELLANOS ET AL. CHANGES IN THE QUALITY OF GROUNDWATER FOR AGRICULTURAL USE IN GUANAJUATO CHANGES IN THE QUALITY OF GROUNDWATER FOR AGRICULTURAL USE IN GUANAJUATO Cambios en la Calidad del Agua Subterránea para Uso Agrícola en Guanajuato J.Z. Castellanos1‡, A. Ortega-Guerrero2, O.A. Grajeda1, A. Vázquez-Alarcón3, S. Villalobos1, J.J. Muñoz-Ramos1, B. Zamudio1, J.G. Martínez4, B. Hurtado1, P. Vargas1, and S.A. Enríquez5 SUMMARY complicated problems in the management of soil fertility may arise in the near future. By the same To study changes in the quality of groundwater for token, it is necessary to carry out systematic studies agricultural use in the State of Guanajuato over the on groundwater that will allow us to identify the last 18 years, information from 1982 to 1998 geochemical processes that control increases of the produced in INIFAP’s Laboratorio de Suelos y Aguas water quality variables mentioned above, and so be del Campo Experimental Bajío (“Soil and Water able to take them into account in the planning the Laboratory of the Bajío Experimental Station”) was exploitation of the aquifer and agricultural activity in reviewed. The variables included in the analysis the region. were: CE, pH, Na, K, Ca and Mg, Cl, SO4, HCO3, CO3, SAR and CSR. Each one of these variables was Index words: Electrical conductivity, pH, sodium related to time, measured in years. These values were absorption ratio, residual sodium carbonate. then used to determine the regression equations, for which the SAS statistical package was used. This RESUMEN allowed us to analyze the tendencies of each water quality parameter over the evaluation period. It could Con el fin de estudiar los cambios que ha sufrido be observed that groundwater in Guanajuato is la calidad del agua subterránea para uso agrícola en el experiencing an increase in the concentration of estado de Guanajuato en los últimos 18 años, se revisó sodium, SAR, and pH through time, possibly as a la información generada en el Laboratorio de Suelos y result of incorrect use. On the other hand, the Aguas del Campo Experimental Bajío del Instituto concentrations of Ca, Mg, and K, that would Nacional de Investigaciones Forestales y constitute part of the cations that are beneficial to soil, Agropecuarias desde 1982 hasta 1998. Las variables have not been significantly modified in the period incluidas en el análisis fueron: CE, pH, cationes: Na, studied. The highest concentration of sodium was K, Ca y Mg, aniones: Cl, SO4, HCO3, CO3, RAS y found in water samples taken in the southeastern zone, CSR. Cada una de las variables antes mencionadas se where the negative effects on soil and on the nutrition relacionó con el tiempo en años y con esos valores se of crops, such as sorghum, have already been determinaron las ecuaciones de regresión, utilizando observed. If measures are not taken to avoid the el paquete estadístico SAS. Esto permitió analizar las indiscriminant management of the aquifer and, tendencias de cada parámetro de calidad del agua a consequently, the reduction of piezometric levels, then través del período de evaluación. Se pudo observar que las aguas subterráneas de Guanajuato están 1 Instituto Nacional de Investigaciones Forestales y incrementando significativamente la concentración de Agropecuarias. 38010 Celaya, Guanajuato, México. sodio, el RAS y el pH a través del tiempo, ‡ ([email protected]) 2 Instituto de Geología, Universidad Nacional Autónoma de posiblemente como resultado de la explotación México. Apartado Postal 70-296, Cd. Universitaria, inadecuada del agua subterránea. Por otro lado, las 04510 México, DF. concentraciones de Ca, Mg y K, que formarían parte 3 Departamento de Suelos, Universidad Autónoma Chapingo. de los cationes benéficos para el suelo, no se han Chapingo, Estado de México. modificado significativamente en dicho período. La 4 CENID-RASPA, Instituto Nacional de Investigaciones Forestales y Agropecuarias. Gómez Palacios, Durango. mayor concentración de sodio se observó en el agua 5 Instituto Tecnológico y de Estudios Superiores de Monterrey, extraída en la zona suroeste, donde ya se ven los Campus Querétaro. Querétaro, México. efectos negativos en el suelo y en las características nutricionales de los cultivos, como el sorgo. Si no se Recibido: Enero de 2001. Aceptado: Diciembre de 2001. Publicado en Terra 20: 161-170. toman las medidas para evitar el manejo 161 TERRA VOLUMEN 20 NUMERO 2, 2002 indiscriminado del acuífero con el consecuente “Adjusted SAR”) takes into account the precipitation abatimiento de los niveles piezométricos, pueden of calcium in the form of carbonates. In both cases, provocarse problemas de difícil manejo de la the cations in the equations are expressed in me/L, fertilidad del suelo en un futuro cercano. De igual while the units of SAR are adimensional. manera, es necesario realizar estudios sistemáticos del The residual sodium carbonate agua subterránea, que permitan identificar los [CSR = (CO3+HCO3)-(Ca+Mg)], expressed in me/L, procesos geoquímicos que controlan el incremento de is another indicator of the danger of the increase in the las mencionadas variables de la calidad del agua, con concentration of sodium in the soil, because it also el fin de considerarlos en la planeación del takes into account the precipitation of calcium and aprovechamiento del acuífero y de la actividad magnesium as carbonates and bicarbonates, once the agrícola regional. water comes into contact with the soil, and propitiates the reduction of the antagonistic effect of these two Palabras clave: Conductividad eléctrica, potencial divalent cations on the sodium. Aceves (1979) hidrógeno, relación de absorción de sodio, carbonato indicated that the ranges for classifying waters de sodio residual. according to this variable are < 1.25 me/L, good water; from 1.25 to 2.50 me/L, marginal water; and INTRODUCTION > 2.50 me/L, water with a great risk of causing higher concentrations of sodium in the soil. The development of a more high-tech agriculture During recent years, in the region known as “El in areas characterized by arid and semi-arid climates Bajío” in Guanajuato, the agricultural area detected as depends on the availability of water for irrigation that having problems of iron deficiencies related to crops is sufficient in terms of quantity and acceptable in such as sorghum, corn and even wheat has been terms of quality. This input is the basis for planning increasing steadily (J. Antonio González, pers. an intensive system of agricultural exploitation with comm.). Solving the nutrient problem has become sustainable characteristics. Water quality plays an more and more difficult. It has been suggested that the important role in the management of irrigation and cause of this problem is associated with an increase in leaching fraction (Ayers and Wescot, 1985), as well as the level of sodium in the soil, but this has not been in the treatment of the water itself, so as to achieve an sufficiently well documented. This possible increase optimal level of production in situations where drip in the level of sodium in the water would provoke a irrigation systems are used (Burt et al., 1995). natural increase in the sodium bicarbonate content and From an agricultural perspective, the principal in soil pH, that could cause a physiological deficiency variables to be evaluated in the classification of water of iron which —from a nutritional point of view— is quality are a) the concentration of dissolved solids and difficult to manage (Uvalle-Bueno et al., 1996). On salts (CE), b) the relative presence of sodium (SAR), the other hand, a severe decrease in the piezometric c) the carbonate and bicarbonate content (CSR), and levels of groundwater in the State of Guanajuato d) the concentration of other specific ions, such as (Chávez, 1998) has been observed as a consequence chlorine and boron (Aceves, 1979; Castellanos et al., of the irrational exploitation of the aquifer. Changes in 2000c). the quality of groundwater proportional to decreases In irrigation water, sodium propitiates the in piezometric levels have been reported for other dispersion of colloids or clays when it comes into areas of the world, such as southeastern Spain (Pulido, contact with the soil and displaces the divalent cations 2+ 2+ 1998), south Texas, and northern Chihuahua (Samani, Ca and Mg . This has a negative effect on the 1998). However, up to now no study has been structure of the soil and reduces its capacity to reported in Mexico that indicates changes in conduct water and air through its profile (Castellanos groundwater quality through time. et al., 2000b). This, in turn, damages soil fertility, The objective of our study was to examine the because in addition to affecting aeration it also increases pH and reduces the availability of Fe and changes that the quality of groundwater for Zn. The concentration of sodium is expressed as the agricultural use has been experiencing in the State of relative presence of Na+ compared to Ca2+ and Mg2+: Guanajuato over the past 18 years, on the basis of the 1/2 1/2 SAR = Na/[(Ca+Mg)/2] and SARaj = Na/[(Cax+Mg)/2] recompilation and evaluation of laboratory reports on (Suárez, 1981).