Soil Chemistry after Irrigation with Treated Wastewater in Semiarid Climate

Abstract

Soil irrigation using treated wastewater in the Brazilian semiarid region is a promising practice as this area currently faces water scarcity and pollution of water resources by domestic sewage. The aim of this study was to evaluate the use of treated wastewater in drip irrigation and its effect on the chemistry of soil cultivated with squash (Cucurbita maxima Duch.) Coroa IAC and to verify whether there was an increase in soil salinity under a semiarid climate. The experiment was conducted for 123 days on a farm close to the sewage treatment plant, in a randomized block design with five treatments and four replications. The treatments consisted of two irrigation water depths (100 and 150 % of the evapotranspiration), two applications of gypsum to attenuate wastewater sodicity (0 and 5.51 g per plant), and a control treatment with no application of wastewater or gypsum. During the experiment, treated wastewater and soil gravitational water, at a depth of 0.40 m, were collected for measurement of Na Besides an increase in pH and a reduction in total N, the irrigation with wastewater reduces soil salinity of the naturally salt-rich soils of the semiarid climate. It also led to soil sodification, in spite of the added gypsum, which indicates that irrigation with wastewater might require the addition of greater quantities of gypsum to prevent physical degradation of the soil.

Soil Chemical Properties in Banana Crops Fertigated With Treated Wastewater

“…Similar result was found by Santos et al (2017) in successive maize, cotton, and common bean crops. SOM is usually altered by TTW after several years of use (XU et al, 2010); however, the use of high wastewater rates (150% of the maximum water demand) in semiarid regions can raise the SOM (OLIVEIRA et al, 2016). The results of the present study showed an increase in SOM when compared to that before the experiment implementation (Table 1), presenting averages of 20.8% (0.0-0.2 m layer) and 28.6% (0.2-0.4 m layer); this can be explained by the decomposition of plant residues, such as leaves and stems of banana trees in the experimental area.…”

Suitability of treated wastewater with respect to pH, electrical conductivity, selected cations and sodium adsorption ratio for irrigation in a semi-arid region

“…The observed high pH in August could have been due to the increase in temperature, which could have promoted higher rates of chemical reactions in water (Barron et al, 2006). In contrast the high values of pH could be beneficial in soils experiencing low pH, as it affects mobility of nutrients (Oliveira et al, 2016). Normally, the safe pH range in water is 6.5 to 8.4 (Jeong et al, 2016), but this could vary according to soil type.…”

Cultivation of sunflower irrigated with domestic sewage treated in Quartzarenic Neosol

“…Similar results regarding the accumulation of magnesium in the soil due to the use of wastewater were also observed by Bourazanis et al (2016), when they tested the application of domestic effluents in the hydraulic conductivity of the soil and by Abegunrin et al (2016), when they evaluated the use of different types of effluents in the chemical and physical properties of the soil in relation to the water supply, both concluded that the domestic effluent can be an alternative of Mg to the soil. On the other hand, opposing these results and working with Cucurbita maxima Duch, irrigated with wastewater, Oliveira et al (2016) verified a reduction of Mg levels in the soil. Thus, it can be concluded that the nutrient intake of the wastewater varies for each condition and it is necessary to pay attention to the requirement of the crop.…”