Effect of treated wastewater use on soil and forage crops of Chenopodium quinoa Willd and Zea mays L.

Abstract

Given the scarcity of water resources for agricultural use, it is necessary to promote the use of wastewater for agriculture. The towns of Capulálpam de Méndez and Ixtlán de Juárez in the State of Oaxaca have anaerobic wastewater treatment plants (WWTP). The morphological growth, biomass production and N and P content were evaluated in two forage species —Chenopodium quinoa Willd and Zea mays— irrigated with treated wastewater (TWW). A complete randomized design (CRD) was established in each municipality, given the homogeneity of the soil, using a 2 x 2 factorial arrangement, i.e., two forage crops (Quinoa and corn) and two types of irrigation (fresh water and treated wastewater), with 4 replicates per treatment. Analyses of variance and Tukey mean tests (P≤0.05) were performed for the studied variables. In the soils, the pH level was "moderately acid" to "neutral" (5.1 to 7.3); the EC indicated "negligible effects of salinity"; organic matter was found at intervals of "medium to high", and the texture was sandy clay loam in Ixtlán and clay loam in Capulálpam. Growth variables (plant height, stem diameter, and number of leaves) and biomass were significantly higher in plants irrigated with treated wastewater in both forage crops. Nitrogen and phosphorus contents were significantly higher in quinoa and corn plants receiving TWW. TWW could be an alternative that would help reduce the use of chemical fertilizers, as it is an important source of nutrients in forage crops.