Microbial quantities and enzyme activity in soil irrigated with sewage for different lengths of time

Abstract

Sewage is widely used on agricultural soils in peri-urban areas of developing countries to meet shortages of water resource. Although sewage is a good source of plant nutrients, it also increases the heavy metals loads to soils. Microbial responses to these contaminants may serve as early warning indicators of adverse effects of sewage irrigation on soil quality. The purpose of this study was to assess the effect of time of sewage irrigation on soil microbial indicators. Soil samples were collected from seven soil sites (S1-S7) irrigated with 0 years, 16 years, 23 years, 25 years, 27 years, 32 years and 52 years, respectively in Shijiazhuang of China and analyzed. For each soil sample, we determined the quantities of bacteria, fungi and actinomycete, and enzyme activities of urease, sucrase, phosphatase, dehydrogenase and catalase. Our results showed that the soils of S2-S7 irrigated with sewage effluents for different times (ranged between 16 and 52 years) exhibited higher densities of bacteria, actinomycete, urease, sucrase and phosphatase but lower densities of fungi when compared with S1 irrigated with sewage effluents for 0 years. The soil S7 irrigated with sewage effluents for longest times (52 years) contained lowest activities of catalase when compared with the soils of S1-S6. The densities of bacteria (R = 0.877, p < 0.01), actinomycete (R = 0.875, p < 0.01), sucrase (R = 0.858, p < 0.01) and phosphatase (R = 0.804, p < 0.05) were significantly correlated in a positive manner with time of sewage irrigation. Soil fungi quantities and urease, dehydrogenase and catalase activities did not change significantly with irrigation time. This study confirms that sewage irrigation had negative effects on microbial properties including fungi, catalase and dehydrogenase in the long term, so there is a need for continuous monitoring for sustainable soil health.

Effect of Sewage Irrigation on the CT-Measured Soil Pore Characteristics of a Clay Farmland in Northern China

“…Several studies have showed that the time of sewage irrigation can significantly affect the physicochemical and microbial properties of soil [ 43 , 44 ]. Lucho-Constantino et al [ 43 ] reported that the relation between the contents of organic carbon, total boron, and total lead and time of sewage irrigation (6–41 years) was clearly positive.…”

“…Lucho-Constantino et al [ 43 ] reported that the relation between the contents of organic carbon, total boron, and total lead and time of sewage irrigation (6–41 years) was clearly positive. Guo et al [ 44 ] reported that the contents of bacteria numbers, actinomycete numbers, sucrase activity and phosphatase activity were significantly correlated in a positive manner with time of sewage irrigation (0–52 years). In this study, we discussed the effects of sewage irrigation time on soil pore.…”

Soil Microbial Communities and Enzyme Activity for Different Reclamation (Ecological Restoration) Patterns of Abandoned Farmlands in Shihezi, Xinjiang, China

“…However, the soil physical and chemical properties, vegetation composition, history of abandonment, climatic features and the plant types of reclamation (restoration) varied with the changes to abandoned farmlands; the effects of RRAF patterns on soil biochemical properties changed in different regions, and there were even some opposing conclusions. Some researches have reported that soil microbial communities and enzyme activity increases after land reclamation (ecological restoration) (Tan and Kang, 2009;Liu et al, 2013;Guo et al, 2014). Nevertheless, other studies have found that the decline in soil organic C results in a decrease in soil bacteria, fungi and actinomycetes (Yin et al, 2013), the catabolic diversity of soil microbial communities (Degens et al, 2000) and urease activity (Raiesi and Beheshti, 2014) after RRAF.…”