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This study was used to examine the possibility of microbial bioaugmentation of subsurface soil with the subsurface irrigation for use as a biofiltration/biocontrol technology for agricultural pollutants. The study is broken down into an introduction, a discussion of the experiment and a discussion of its results. Various tables and graphs accompany the article.

This paper describes the development of an artificial neural network (ANN) model to simulate fluctuations in midspan water-table depths and drain outflows, as influenced by daily rainfall and potential evapotranspiration rates. Unlike conventional models, ANN models do not require explicit relationships between inputs and outputs. Instead, ANNs map the implicit relationship between inputs and outputs through training by field observations. Compared with conventional models, the ANN model requires fewer input parameters since the inputs that remain constant are not considered by ANNs. Therefore ANNs can be executed quickly on a microcomputer. These benefits can be exploited in the real-time control of water-table management systems. The model was developed using field observations of water-table depths from 1991 to 1993 and drain outflows from 1991 to 1994 made at an agricultural field in Ottawa, Canada. The root mean squared errors and standard deviation of errors of simulated results were found to range from 46.5 to 161.1 mm and 46.6 to 139.2 mm, respectively, thus showing potential applications of ANNs in land drainage engineering.

CAT scans show how liquids flow through tiny tunnels in soil Worms and roots burrow into soil leaving trails that can quickly carry applied pesticides and other chemicals into ground [...]

Laboratory and field studies were conducted to evaluate the adsorption behavior of a biocharamended sandy soil for Escherichia coli (E. coli). Two types of biochars, produced respectively by either slow pyrolysis (SPB) or fast pyrolysis (FPB), were used. In the laboratory study, soil+SPB and soil+FPB treatments (99:1 soil:biochar by weight) resulted in a significantly higher adsorption after 24 hours as compared to soil alone (H0: p<0.05). After 7 days, the concentration of E. coli in solution phase were 0.87±0.08 x 106 , <1.00 x 103 , and 1.17±0.15 x 104 in soil alone, soil+SPB and soil+FPB treatments, respectively. The effectiveness of soil/biochar amendments was further tested on field lysimeters by studying the fate and transport of total and fecal (E. coli) coliforms from poultry manure. Four irrigation events were simulated. Periodic soil samples at three sampling depths as well as leachate samples were collected and analyzed. Total coliforms and E. coli were found to move through the soil profile (0.10 m, 0.31 m and 0.52 m), although their concentrations decreased with soil depth and time. In biochar-amended lysimeters, the concentration of total coliforms was significantly lower (H0: P< 0.05) than in control (soil alone) lysimeters, at most sampling times. The concentrations of E. coli in the biochar treatments, at the three soil sampling depths and in the leachate, were also significantly lower than in the control (H0: P < 0.05). Therefore, both biochar amendments were effective in reducing leaching of E. coli through the soil profile and in providing a fecal coliformfree leachate. This study shows that biochar can play an important role in improving drainage water quality and in addressing the concerns for pathogen leaching as a result of the use of poultry manure on agricultural land. Laboratory and field studies were conducted to evaluate the adsorption behavior of a biocharamended sandy soil for Escherichia coli (E. coli). Two types of biochars, produced respectively by either slow pyrolysis (SPB) or fast pyrolysis (FPB), were used. In the laboratory study, soil+SPB and soil+FPB treatments (99:1 soil:biochar by weight) resulted in a significantly higher adsorption after 24 hours as compared to soil alone (H0: p<0.05). After 7 days, the concentration of E. coli in solution phase were 0.87±0.08 x 106, <1.00 x 103, and 1.17±0.15 x 104 in soil alone, soil+SPB and soil+FPB treatments, respectively. The effectiveness of soil/biochar amendments was further tested on field lysimeters by studying the fate and transport of total and fecal (E. coli) coliforms from poultry manure. Four irrigation events were simulated. Periodic soil samples at three sampling depths as well as leachate samples were collected and analyzed. Total coliforms and E. coli were found to move through the soil profile (0.10 m, 0.31 m and 0.52 m), although their concentrations decreased with soil depth and time. In biochar-amended lysimeters, the concentration of total coliforms was significantly lower (H0: P< 0.05) than in control (soil alone) lysimeters, at most sampling times. The concentrations of E. coli in the biochar treatments, at the three soil sampling depths and in the leachate, were also significantly lower than in the control (H0: P < 0.05). Therefore, both biochar amendments were effective in reducing leaching of E. coli through the soil profile and in providing a fecal coliformfree leachate. This study shows that biochar can play an important role in improving drainage water quality and in addressing the concerns for pathogen leaching as a result of the use of poultry manure on agricultural land. [ABSTRACT FROM AUTHOR]