Soil property changes after four decades of wastewater irrigation: A landscape perspective

ArticleinCatena 73(1):63-74 · March 2008with19 Reads
DOI: 10.1016/j.catena.2007.09.002
For over 40 years, The Pennsylvania State University (PSU) has irrigated its wastewater onto both cropped and forested lands. Despite local weather conditions, approximately 50 mm/week of wastewater have been spray-irrigated onto the land since 1962. This irrigation, combined with the natural precipitation, amounts to approximately 3550 mm of water per year. The objective of this study was to investigate the morphological and functional changes in soils of this area as a result of this significantly-increased water load. The research area has a karst geology and is dominated by rolling hills with many small depressions that act as sinks for water and sediments. Together with six soil trenches, 47 soil cores were taken across a 6.5-ha field. Previous studies conducted at this site provided a reference for interpreting the changes in soil properties over time. Soil morphological properties, including structure, horizonation, and redoximorphic features, were evaluated from the soil cores and in situ soil pits. In addition, soil functional parameters, including saturated hydraulic conductivity (Ksat), bulk density, organic matter content, and soil pH, were evaluated to determine the soil functional changes. Results indicate that the soils have experienced periods of local saturation and soil transport, which are reflected by the distribution of redoximorphic features and A-horizon thickness across the study area. Sample locations were grouped into three landscape positions (summit, midslope, and depression) that exhibited similar soil properties. The depth of the A-horizon was significantly greater in the depressions, while the midslope position had the highest manganese oxide coating percentage, and the summit position had the highest bulk density. This reflects the likely hydrologic path from the summit to the depression. The depression areas had the highest mean surface Ksat (10.2 cm/h), while the summit areas had the lowest mean surface Ksat (1.2 cm/h). Both organic matter content and soil pH have increased considerably since 1971. Overall, although soil properties have changed through the decades of irrigation, the wastewater spray irrigation system remains functional in this area and the soils are still performing reasonably well; however, some concerns about reduced soil functionality need to be addressed from a landscape perspective in order to sustain this system.
    • "Treated wastewater effluent is irrigated on both cropped and forested land for 12-h periods, with each irrigation event delivering roughly 54 mm. The average rate of irrigation is about 30 mm/week (1580 mm/year) (Walker and Lin, 2008). Irrigation at the Living Filter continues year-round, as allowed by its permit, even during frozen conditions and large precipitation events. "
    [Show abstract] [Hide abstract] ABSTRACT: To quantify the frequency of preferential flow (PF) occurrence and its controls, and to examine the interactions of soils and irrigation on water flow dynamics, soil moisture was monitored at six depths every two minutes at four sites in a wastewater spray irrigation field from 2009 to 2011. Two irrigated sites – one cropped and another forested – were compared with two corresponding non-irrigated sites. Activation of preferential flow pathways was determined from the sequences of soil moisture responses at various depths for a total of 633 water input events, including 82 irrigation events. The results showed that the overall averaged frequencies of PF at the non-irrigated sites were 24.9% at the cropped site and 24.7% at the forested site. By contrast, the averaged frequencies at the irrigated sites were 47.1% at the cropped site and 45.0% at the forested site. The temporal stability of PF frequency was evaluated, showing that the overall frequency of PF stabilized after 70 events at non-irrigated sites, while the irrigated sites took as many as 105 events (24 of which were irrigations). Associations between 20 possible controls related to water input, moisture response, and season were quantified using the Student’s t-test between each parameter and PF detection. The most influential factors were water inputs, especially the total input and peak input intensity. Antecedent soil moisture and response slope (maximum 2-min increase in moisture content during the response) were also significant in some but not all cases. Soil horizonation influenced soil water storage and dynamics by restricting flow and causing perched water tables. Irrigated sites experienced saturated conditions for as much as 38% of the monitoring time at some depths, compared to a maximum of 3% at non-irrigated sites. Preferential flow was not only more likely to occur during irrigation events, but also during natural events at the irrigated sites, suggesting that the irrigated soils have physically adapted to accommodate large volumes of water, after decades of spray irrigation. The results of this study have implications for understanding hydrology and contaminant fate in anthropogenically-altered landscapes as well as implementing sustainable management practices.
    Full-text · Article · Dec 2016
    • "In the U.S.A., soils have experienced periods of local saturation and soil transport, which are refl ected by the distribution of redoximorphic features and A-horizon thickness across the study area. Both organic matter content and soil pH have increased considerably (Walker and Lin 2008 ). In China, Chiou ( 2008 ) concluded that in terms of reuse impact in soil contamination, the most possible heavy metal caused accumulation was arsenic. "
    [Show abstract] [Hide abstract] ABSTRACT: The need for irrigated agriculture is growing day by day and the largest water withdrawals from renewable water resources are for irrigation. In addition, the available water resources are decreasing and we need to use non-conventional water resources for irrigation due to looming water crisis (Raschid-Sally and Jayakody, Drivers and characteristics of wastewater agriculture in developing countries: results from a global assessment. International Water Management Institute, Colombo, 35p, (IWMI Research Report 127), 2008). However, the volume of treating and using wastewater is limited due to the lack of adequate data and knowledge and/or negative effects of improper wastewater management (i.e. use of untreated wastewater). A comprehensive evaluation of what has been done is necessary in order to explore wastewater irrigation and to avoid trial-and-error policies. Although a study of wastewater irrigation from crops, soil, groundwater, health, irrigation equipments, modern technologies, and other environmental aspects is useful, management studies in comparison with other aspects can help lead to more reliable and more extensive findings and finally a better decision on using wastewater for irrigation. The chapter presents challenges and prospects that may help decision making for the use of wastewater in irrigation.
    Full-text · Chapter · Jan 2016 · Agricultural Water Management
    • "La utilización del agua regenerada en la agricultura aporta más nutrientes al suelo, pero también puede aumentar las concentraciones de metales pesados y la tasa de infección por patógenos (). Asimismo, en los terrenos agrícolas regados durante décadas con aguas regeneradas se han podido comprobar efectos desfavorables en el suelo relacionados con la acumulación de sales en los horizontes superficiales, especialmente en los climas más secos (Walker, 2008). Sin embargo, en un estudio reciente llevado a cabo en siete parques de Pekín se observó un aumento de la salinidad del suelo regado con agua regenerada frente a los regados con agua potable, aunque sin diferencias significativas y, además, se constató una mejoría en los nutrientes disponibles en el suelo para las plantas así como en la actividad de los microorganismos (Chen et al., 2015 y la vegetación a medio plazo, por lo que, a la vista de nuevos ensayos, deberían ser revisados los criterios de los autores citados anteriormente. "
    Full-text · Chapter · Nov 2015 · Agricultural Water Management
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