accumulation in the top layer (Christou et al. 2017). Guédron et al. (2014) conveyed
via application of untreated wastewater in irrigated land of Mezquital Valley,
Mexico City, the presence of high concentrations of metals such as methylmercury
and lead. Addition of non-reclaimed wastewater for 10 years in the agricultural land
of Harare, Zimbabwe, had exceeded the heavy metals more than acceptable limits
(Mapanda et al. 2005). Furthermore, increased soil salinization, alkalinization/acidification, and structural deterioration had observed reduced soil productivity (Klay
et al. 2010). Wastewater promotes a continuous supply of organic matter and
microorganisms with the help of information and stability of soil aggregates
(Durán–Álvarez and Jiménez–Cisneros et al. 2014). Saha et al. (2010) reported
that untreated sewage irrigation for 5 years has significantly increased the number
of fungi and actinomycete population in the surface soil by, respectively, about
125% and 75%. But ratios of bacteria to fungi and actinomycetes to fungi decreased
considerably in both the layers due to sewage irrigation for 5 years. This indicates
that an increase in the fungal population was more than the proportional increase in
bacteria and actinomycete population, which may be due to the influx of active C
through untreated sewage water.
Chaerun et al. (2011) have compared the CO2-C evolution between controlled
and industrial wastewater irrigated land. Even after, 31 years of irrigation, the
contaminated soil showed higher CO2-C evolution in waste water irrigated soils
and has consistent with the exceeded levels of extractable total DNA and higher
levels of microbial biomass. The high CO 2 respiration activity in polluted soil was
indicative of higher utilization of organic matters by the microbial community,
consistent with its high organic C availability (Yang et al. 2019).
To investigate the health of soil microorganisms in response to wastewater
application, different soil enzymes are analyzed such as dehydrogenase, urease,
alkaline phosphatase, catalase, and glucosidase. Among all the enzymes, dehydrogenase activity depicts the metabolic status of the soil and can act as an important
indicator of microbial activity (Nannipieri et al. 2003). The activity of the dehydrogenase enzyme is usually higher in wastewater-irrigated land and strongly depends
on concentrations of wastewater (Garcıa-Gil et al. 2000; Arif et al. 2016). Moreover,
activities of soil enzymes are very sensitive to the concentrations of toxic substances
such as salts and heavy metals. Xian et al. (2015) reported that higher concentrations
of heavy metals in wastewater inhibited the activities of soil enzyme and microbial
metabolism. Table 8.2 shows numerous studies that have reported positive or
negative effects of wastewater on soil properties and ultimately on soil health
(Rutkowski et al. 2007; Mosse et al. 2011; Morugán-Coronado et al. 2013).
8.4.2 On Plant Characteristics
Agricultural use of wastewater is a sustainable approach, but this technique is
followed up from ancient time, or we can say “old wine in a new bottle.” Wastewater
is a continuous and good source of nutrients and provides adequate moisture
8 Application of Wastewater in Irrigation and Its Regulation with Special. . .
183
via application of untreated wastewater in irrigated land of Mezquital Valley,
Mexico City, the presence of high concentrations of metals such as methylmercury
and lead. Addition of non-reclaimed wastewater for 10 years in the agricultural land
of Harare, Zimbabwe, had exceeded the heavy metals more than acceptable limits
(Mapanda et al. 2005). Furthermore, increased soil salinization, alkalinization/acidification, and structural deterioration had observed reduced soil productivity (Klay
et al. 2010). Wastewater promotes a continuous supply of organic matter and
microorganisms with the help of information and stability of soil aggregates
(Durán–Álvarez and Jiménez–Cisneros et al. 2014). Saha et al. (2010) reported
that untreated sewage irrigation for 5 years has significantly increased the number
of fungi and actinomycete population in the surface soil by, respectively, about
125% and 75%. But ratios of bacteria to fungi and actinomycetes to fungi decreased
considerably in both the layers due to sewage irrigation for 5 years. This indicates
that an increase in the fungal population was more than the proportional increase in
bacteria and actinomycete population, which may be due to the influx of active C
through untreated sewage water.
Chaerun et al. (2011) have compared the CO2-C evolution between controlled
and industrial wastewater irrigated land. Even after, 31 years of irrigation, the
contaminated soil showed higher CO2-C evolution in waste water irrigated soils
and has consistent with the exceeded levels of extractable total DNA and higher
levels of microbial biomass. The high CO 2 respiration activity in polluted soil was
indicative of higher utilization of organic matters by the microbial community,
consistent with its high organic C availability (Yang et al. 2019).
To investigate the health of soil microorganisms in response to wastewater
application, different soil enzymes are analyzed such as dehydrogenase, urease,
alkaline phosphatase, catalase, and glucosidase. Among all the enzymes, dehydrogenase activity depicts the metabolic status of the soil and can act as an important
indicator of microbial activity (Nannipieri et al. 2003). The activity of the dehydrogenase enzyme is usually higher in wastewater-irrigated land and strongly depends
on concentrations of wastewater (Garcıa-Gil et al. 2000; Arif et al. 2016). Moreover,
activities of soil enzymes are very sensitive to the concentrations of toxic substances
such as salts and heavy metals. Xian et al. (2015) reported that higher concentrations
of heavy metals in wastewater inhibited the activities of soil enzyme and microbial
metabolism. Table 8.2 shows numerous studies that have reported positive or
negative effects of wastewater on soil properties and ultimately on soil health
(Rutkowski et al. 2007; Mosse et al. 2011; Morugán-Coronado et al. 2013).
8.4.2 On Plant Characteristics
Agricultural use of wastewater is a sustainable approach, but this technique is
followed up from ancient time, or we can say “old wine in a new bottle.” Wastewater
is a continuous and good source of nutrients and provides adequate moisture
8 Application of Wastewater in Irrigation and Its Regulation with Special. . .
183