Agronomic quality of wastewater in Tula and Alfajayucan irrigation districts

Abstract

Wastewater provides nutrients for crops and increases the volume of water available for irrigation, but it represents risks such as salinization and sodification of soils, toxicity to plants, and risks to human health. With the objective of identifying the risks of salinization and sodification of soils in the irrigation districts Tula and Alfajayucan, the physical and chemical characterization of 70 water samples taken from canals, rivers, dams, and springs was carried out. The analysis of the parameters pH and electrical conductivity (EC) was carried out, and the concentration of the next ions was determined: Ca²⁺, Mg²⁺, Na⁺, K⁺, CO₃^2–, HCO₃^–, Cl^–, SO₄^2–, B and PO₄^3–. Only 5.7 % of the sampled sites have good agronomic water quality, according to the EC; Na⁺, HCO₃^– and Cl^– predominate in all the sampled sites, which give rise to the formation of NaHCO₃ and NaCl salts, which are toxic to most crops; there is a risk of infiltration reduction in 65.7 % of the sampled sites; in 87.1 % of the sites, boron is found in concentrations that can be toxic to crops, and in 48.6 % the concentration of 2 mg/L of orthophosphates is exceeded. With the parameters evaluated, it is concluded that the agronomic quality of the water used in Tula and Alfajayucan irrigation districts is deficient, due to the high risks of salinization and sodification of the soil, as well as toxicity to crops.