Nitrogen movement in two Manitoba soils
The movement of nitrogen from calcium nitrate, urea and ammonium sulphate surface-applied at the rate of 500 lb N per acre was studied in two Manitoba soils. During the 1971 experimental period which lasted from June until October, the greatest movement occurred from Ca(No3)2. There was some difference in the downward movement of nitrogren from urea and (NH4)2SO4 depending upon the soil. The rate of oxidation of ammonium to nitrate was more rapid, and the depth of penetration of nitrogen greater in the Portage loam than in the Red River clay. Migration of ammonium from the point of application was limited in both soils. The distribution of nitrogen in the Red River soil in spring and fall of the year following application showed an almost total disappearance of applied nitrogen from the (NH4)2SO4 plot, and a partial disappearance from the urea and Ca(NO3)2 plots. There was some upward movement of nitrogen in the spring. However, by the fall sampling there was further downward movement of nitrogen into the soils profile. A similar study was not carried out on the Portage loam... Dentrification was found to take place in the soil columns. The rate was more rapid in the Portage soil than in the Red River soil, and was related to the initial moisture content. A more rapid denitrification rate occurred at the higher moisture content. The substitution of Ca(NO3)2 with AgNO3 as a tracer resulted in a slower rate of denitrification, but there was also a difference in moisture and nitrate movement.