Date of this Version
Thesis (M.S.)—University of Nebraska—Lincoln, 1971. Department of Agronomy.
The distribution of organic carbon and several nitrogen fractions in virgin and cultivated Keith and Rosebud profiles were studied.The concentrations of organic C, total N, C:N ratio, HCl hydrolyzable N, nonhydrolyzable N, hydrolyzable NH4-N, hexosamine N, hydroxyamino acid N, alpha amino acid N, exchangeable NH4-N, and nitrate + nitrite N were highest in the surface and decreased with increasing depth in most of the profiles.The nonexchangeable NH4-N concentration decreased with increasing depth in the Rosebud profiles.In the Keith profiles the nonexhangeable NH4-N concentration increased with increasing depth through the B horizon and then decreased with increasing depth in the C horizon.
As a percentage of the total N, the hexosamine N and the hydroxyamino acid N decreased with increasing depth; the hydrolyzable N, nonhydrolyzable N alpha amino acid N, and nitrate + nitrite N remained constant with increasing depth; and the hydrolyzable NH4-N, nonexchangeable NH4-N, and exchangeable NH4-N increased with increasing depth.
The percentage of the total N as hexosamine N, hydroxyamino acid N, and alpha amino acid N was less in the cultivated profiles than in the virgin profiles indicating a rate of loss greater than total N loss as a whole.The percentage of the total N as hydrolyzable N and nonhydrolyzable N remained constant upon cultivation indicating a loss which was proportional to the total N loss.The percentage of the total N as hydrolyzable NH4-N and nonexchangeable NH4-N increased upon cultivation indicating a smaller loss than total N as a whole.
Advisor: G. A. Peterson