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The cost and time involved in frequent field observations pertaining to quantification of nitrate leaching below the crop root zone leads to the use of simulation models, which is a more plausible approach. Nitrate leaching below the root zone of a maize-wheat cropping system under surface irrigation was assessed. The model's predicted results pertaining to water percolation and nitrate leaching were in line with the observed data, with root mean square error (RMSE) values close to zero, and index of agreement values close to 1. The seasonal percolation of water below 120 cm soil depth in maize and wheat were 36.5 and 27.5% of applied water, respectively. Similarly, nitrate leaching below 120 cm soil depth was 18.1 and 14.3% of the applied nitrogenous fertilizer in maize and wheat, respectively. Under similar conditions, the nitrate leaching under a maize-wheat cropping system was 6.8 kg NO3 ha-1 less than in a rice-wheat cropping system. Furthermore, nitrate leaching below the crop root zone under different fertilizer application rates was estimated and best-fit second-order polynomial equations were developed. The equations can be used for estimation of nitrate leaching under different fertilizer input scenarios of maize-grown and wheat-grown areas under similar hydro-agro-climatic regions. [ABSTRACT FROM AUTHOR]

Treated hazardous material at the North Carolina State University (NCSU) Lot 86 National Priorities List (NPL) Site was evaluated using unconfined compressive strength (UCS) as a surrogate performance standard for the toxicity characteristic leaching procedure (TCLP). During a preconstruction treatability study, UCS test results were related to the TCLP performance standards as stipulated in the record of decision. During construction, 113 UCS samples were obtained and test results indicated that over 8,410 m3(11,000 yd3) of pre-RCRA (Resource Conservation and Recovery Act) chemical waste generated from the University’s educational and research laboratories had been successfully stabilized. Using a crane-mounted mixing unit for a portion of the stabilization operations, and a trackhoe unit for the remainder of the construction, 2.03 Gg(2,240 t) of cement and 2.81 ML(743,000 gal.) of water were mixed with impacted soil and waste material resulting in a 3 m(10 ft) thick encapsulated monolith half the size of a football field. [ABSTRACT FROM AUTHOR]

Presents information on a study which evaluated the performance and leaching of controlled low strength materials incorporating fly ash and foundry sand. Methodology of the study; Results and discussion on the study; Conclusions.