A computer simulation model for investigating the effect of land application of sludge on runoff water quality

CREAMS-NT, a modified version of the field-scale model for Chemicals, Runoff, and Erosion from Agricultural Management Systems (CREAMS) model, was developed to simulate the nitrogen (N) transformations and subsequent nutrient transport processes which occur in the soil following organic waste applications. CREAMS-NT accounts for nutrient addition through fertilization and rainfall and losses of N by volatilization, denitrification, plant uptake, leaching, and overland flow. Data required by CREAMS-NT includes runoff volume, sediment yield, percolation, and soil environmental conditions which is generated by the hydrologic and erosion components of the original CREAMS model. The mineralization, nitrification, denitrification, ar1d volatilization processes are simulated using firstâ order knetic equations adjusted for the effects of soil environmental conditions including temperature, moisture, pH, soil/sludge contact, and soil cation exchange capacity. Prior to a runoff event, soil ammnonium-N (NH4 â N) is partitioned between adsorbed and desorbed phases. CREAMS-NT predicts the transport of organic-N, NH4 â N, and sediment=bound phosphorus (P3b) in runoff using enrichment ratios. The transport of soluble nutrients, nitrate-N (NO3 â N), NH4 â N, and soluble P (PTF), is estimated using extraction coefficients.