LONG-TERM ANNUAL MANURE APPLICATIONS INCREASE SOIL ORGANIC-MATTER AND NITROGEN, AND DECREASE CARBON TO NITROGEN RATIO

In 1973, a long-term experiment was initiated at Lethbridge, Alberta, Canada to determine the effects of repeated annual applications of cattle feedlot manure, applied at four rates and incorporated by three different tillage methods, on the soil and ground water. The objectives of this study were: (i) to determine the effects of annual applications of manure, with different levels and methods of incorporation, on the accumulation and decomposition (amounts and rates) of organic matter (OM) and N determined by Kjeldahl analysis (total N), and their distribution in the soil; (ii) to develop a model to predict the accumulation of OM and total N in the soil; and (iii) to determine the resulting C/N ratio of the soil.