Soil fertility and agro-physiological responses of maize (Zea mays) irrigated by treated domestic wastewater by hybrid multi-soil-layering technology

Abstract

The depletion of water resources has gained global attention, particularly in arid climates, where there is growing interest in reusing treated wastewater for irrigation. This study focuses on the impact of irrigating treated wastewater using a hybrid multi-soil-layering (MSL) technology on soil physicochemical properties and the agro-physiological characteristics of maize (Zea mays) cultivated in Morocco, a region characterized by arid conditions. To achieve this research goals, three plots were cultivated with Zea mays and subjected to irrigation with water of varying qualities: raw wastewater (RWW), treated wastewater (TWW), and well water (WW). This experiment ran for five months, covering one crop season. The physicochemical and microbiological parameters in the soil and water were investigated, and the agro-physiological characteristics of the maize crops were assessed. The findings revealed significant differences in physicochemical and microbial parameters within both water and soil, as well as in the physiological responses of the maize crop, among the three water treatments. TWW's quality met the permissible limits for direct wastewater discharge, as prescribed by Moroccan norms, making it suitable for potential irrigation reuse. Moreover, the higher content of key elements (Na, K, Ca, and Mg) in WW indicated that TWW was more suitable for irrigation. Zea mays irrigated with RWW and TWW exhibited a higher accumulation of protein and sugar content compared to WW irrigation. Furthermore, the biomass parameters, including root, aerial, and grain dry weight, showed a positive effect on Zea mays irrigated with RWW and TWW compared to WW. Total chlorophyll content, on the other hand, was highest in plants irrigated with WW, followed by TWW. Plants irrigated with RWW produced the highest amounts of nitrogen, phosphorus, and potassium. Conversely, plants irrigated with WW had a higher content of Ca, Na, and Mg. TWW yielded medium concentrations of N, P, K, Ca, Mg, and Na compared to RWW and WW, attributed to the nutrients provided by irrigation with TWW using the hybrid MSL technology. In conclusion, aside from their use as irrigation water, treated wastewater emerges as a valuable source of plant nutrients and soil fertilizers. They offer significant nutritive value, enhancing plant growth, reducing the need for additional fertilizer application, lowering mineral fertilization costs, and increasing the productivity of infertile soils. This highlights the potential of treated wastewater to improve agricultural sustainability in arid regions like Morocco.

Keywords: Agronomy; Irrigation; Processed wastewater; Raw wastewater; Well water; Zea mays.