Leaching and denitrification losses of nitrogen from corn fields as influenced by conventional- and no-till practices in soils of the Chesapeake Bay area

Research was conducted in soils of the Chesapeake Bay area primarily to determine the combined effects of tillage practice and N fertilizer application rates on N leaching and denitrification losses from corn fields. Three well known models--the NTRM, CERES-Maize, and VT-MAIZE--were also tested to determine their predictive ability of N distribution in soil and crop, the various components of the N cycle, and corn yields.; To accomplish the above objectives, two field sites were located (in 1986) for a 3 year study on agronomically important and representative soils that are used for corn production in the Chesapeake Bay drainage basin. The main plot treatment consisted of no-till and conventional-till. The subplot treatments consisted of 6 levels of N application rates with 4 inorganic and 2 organic (sewage sludge) N fertilizers. Denitrification experiments were also conducted on the Groseclose silt loam soil by applying the accetylene inhibition technique. Nitrogen leaching losses were determined by applying the principle of N mass balance.; Denitrification N loss during the corn growing season was less than 2% of the applied N fertilizer. The N loss from the two tillage systems was not significant at p {dollar}>{dollar} 0.10. Fick's law may be applied for predicting N loss subsequent to accetylene application, only if N sampling takes place following a minimum present critical time.; During the growing season, conventional tillage gained generally more N than no-till. During winter, however, N loss due to leaching was proportional to the amount of N retained at the end of the growing season. Thus, conventional tillage lost more N by leaching during the winter months.; Mineralization of N was higher in conventional till, while denitrification was higher in no-till. Split application has shown less N loss due to leaching than the preplant. Mineralization, denitrification, and leaching took place from the upper as well as the lower zones of the soil profile.; The model performances varied from year to year and from one tillage practice to another. The models did not make satisfactory predictions under the severe moisture stress conditions experienced during this study. Thus, they need a great deal of readjustment.