Describes the fertilizer requirements of different soil types, with particular reference to Alberta. These two nutrients are most often responsible for limiting crop yields in Alberta. For crops grown on fallow, phosphorus may be the only nutrient limiting crop yield. Cropfallow rotations rely heavily on nitrogen released from the mineralization of soil organic matter. As a result of frequent fallowing, soil organic matter levels can decline to a point where nitrogen fertilization is required to maintain yields of crops grown on fallow. When the frequency of cropping is extended to cropcropfallow or approaches continuous cropping, nitrogen becomes an increasingly deficient nutrient. Therefore, when the frequency of cropping is increased, higher rates of nitrogen fertilizer, manure or frequent inclusion of legume crops in the rotation are required to maintain high crop yields. This greater need for nitrogen does not indicate that continuous cropping is more detrimental to the soil than cropfallow rotations. The additional nitrogen required to maintain yields in continuous cropping systems helps to maintain soil organic matter.

Address: 7000-113th Street, Edmonton, AB, T6H 5T6
Website: http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex3896