LONG-TERM EFFECTS OF CULTIVATION AND LAND USE ON SOIL QUALITY IN QUEBEC

The purpose of this work is to assess the effects of different land-use practices on the quality of agricultural soils in Quebec. Studies done on three dairy farms, using the traditional rotation of 1 yr of cereals and 4 yr of hay, showed that the conversion of forest soils into agricultural soils caused a drop in nitrogen of 8% for a clay loam soil, but 21 and 31% for the sandy and silty loam soils, while the loss of organic matter was near 33% for the three soils. The decrease in water-stable aggregate was 84% on the clay loam soil and 50% on the two lighter soils. Work done on continuous meadows of 5 yr or longer showed significant increases in organic matter content and water-aggregate stability. Conversion from typical dairy-farm rotations to continuous corn and cereal rotations reduced structural stability and soil organic matter, as well as soil productivity, even when nutrient levels were improved by use of fertilizers. Other preliminary data indicate that soil compaction by heavy farm machinery, and drainage of organic soils may further reduce soil quality.