scholarly journals Impact of treated wastewater on growth, respiration and hydraulic conductivity of citrus root systems in light and heavy soils

2016 ◽  
Vol 36 (6) ◽  
pp. 770-785 ◽  
Author(s):  
Indira Paudel ◽  
Shabtai Cohen ◽  
Avi Shaviv ◽  
Asher Bar-Tal ◽  
Nirit Bernstein ◽  
...  
2015 ◽  
Vol 63 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Karsten Schacht ◽  
Bernd Marschner

Abstract The use of treated wastewater (TWW) for agricultural irrigation becomes increasingly important in water stressed regions like the Middle East for substituting fresh water (FW) resources. Due to elevated salt concentrations and organic compounds in TWW this practice has potential adverse effects on soil quality, such as the reduction of hydraulic conductivity (HC) and soil aggregate stability (SAS). To assess the impact of TWW irrigation in comparison to FW irrigation on HC, in-situ infiltration measurements using mini disk infiltrometer were deployed in four different long-term experimental orchard test sites in Israel. Topsoil samples (0-10 cm) were collected for analyzing SAS and determination of selected soil chemical and physical characteristics. The mean HC values decreased at all TWW sites by 42.9% up to 50.8% compared to FW sites. The SAS was 11.3% to 32.4% lower at all TWW sites. Soil electrical conductivity (EC) and exchangeable sodium percentage (ESP) were generally higher at TWW sites. These results indicate the use of TWW for irrigation is a viable, but potentially deleterious option, as it influences soil physical and chemical properties.


2021 ◽  
Author(s):  
Sare Asli ◽  
Nedal Massalha ◽  
Muhamad Hugerat

Abstract AimsTo determine the effects of treated wastewater (TWW) and dialyzed TWW (DTWW) through dialysis tube with a cut-off at 6000-8000 Da, on the water transport characteristics of maize seedlings (Zea mays L). MethodsLaboratory experiments were conducted to determine the effect of TWW on the hydraulic conductivity of excised roots. Moreover, the effect on transpiration, plant growth, root cell permeability and on the plant fresh and dry weight was determined. ResultsPressurized water flow through the excised primary roots was reduced by 25%-52%, within 90 min of exposure to TWW or DTWW. In hydroponics, DTWW affected root elongation severely by 58 %, while cell-wall pore sizes of same roots were little reduced (by 6%). Additionally, the exposure to TWW or DTWW caused inhibition of both leaf growth rate by (26%-70%) and transpiration by (14%-64%). While in soil growth, the plant fresh and dry weight was also significantly affected but not with secondary DTWW. Conclusions These impacts appeared simultaneously to involve phytotoxic and physical clogging impacts. First, the inhibition in hydraulic conductivity through live roots (phytotoxic and physical effects) after exposure to secondary DTWW was by 22%, while through killed roots accepted after hot alcohol disruption of cell membranes (physical effects only); was only by 14%. Second, although DTWW affected root elongation severely by 58%, cell-wall pore sizes of same roots were little reduced by 6%. We conclude that large molecules, such as polypeptides, remained after the dialysis process, may have produced hormone-like activity that affected root water permeability.


Soil Research ◽  
1999 ◽  
Vol 37 (2) ◽  
pp. 391 ◽  
Author(s):  
G. P. Sparling ◽  
J. C. Williamson ◽  
G. N. Magesan ◽  
L. A. Schipper ◽  
A. Rh. Lloyd-Jones

Application of wastewater can decrease the hydraulic conductivity of soils, and so reduce future loading rates. A possible mechanism for this decrease is blockage of soil pores by microbial growth and extracellular carbohydrate production. Our objective was to determine whether wastewater characteristics that increased microbial biomass and carbohydrate also decreased soil hydraulic conductivity. In field trials, irrigation of secondary-treated wastewater for 7 years onto a sandy soil increased carbohydrate, but had no effect on microbial C or unsaturated hydraulic conductivity, relative to non-irrigated soil. Irrigation of tertiary-treated wastewater for 5 years onto an allophanic soil had no significant effect on these soil characteristics. Effects on soil properties of wastewater with differing carbon : nitrogen (C : N) ratio were examined in the laboratory on repacked cores of the allophanic soil over 14 weeks. Unsaturated hydraulic conductivity decreased significantly in cores irrigated with the high C: N wastewater. These cores also exhibited an increase in soil carbohydrate content, microbial biomass, and respiration relative to cores irrigated with water. This study has demonstrated that the land treatment of industrial wastewaters of high C: N ratio and high biochemical oxygen demand could be problematic, even on freely draining soils.


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