Hills are great in the winter when you want to go tobogganing but they pose a real challenge to farming. Following a few years of cultivation in a conventional tillage system, steep hills tend to develop eroded knolls. With the loss of topsoil and a decreased ability to allow water infiltration on the knolls, a decrease in yield is most often the result. As less and less crop residue is produced, the greater the potential for even more erosion to occur. This cycle can go on and on. But with the adoption of direct seeding, many farmers cropping hills are noticing big differences in both their yields and erosion potential.
Ken Sapsford, Regional Soil Conservationist, who farms near Perdue, has been interested in some of the research currently being conducted in the area. "As a farmer who also contends with hills, I've seen for myself that the soils on the knolls change as the field is direct seeded and continuously cropped. It's good that now we will have some research that can put some numbers on those changes."
Allan Efetha, together with Darwin Anderson and Clint Hilliard of the Soil Science department at the University of Saskatchewan and Jane Elliott of the National Hydrology Research Institute, began a study on tillage and rotations in the Bear Hills ( south of Biggar) in the fall of 1995. The objective of their study was to compare the effects of conventional tillage (CT) and zero tillage (ZT) systems on soil properties at a landscape scale and their effect on potential runoff. The study is also being carried out at the Conservation Learning Centre near Prince Albert and is part of a bigger project investigating the effect of tillage systems on the transport of agricultural chemicals in surface run-off. The entire project is funded by the Canada- Saskatchewan Agricultural Green Plan Agreement.
The research group undertook their study on hills in two different fields. The zero tilled field has been continuously cropped for the past 10 years while the conventional tilled field is under a crop-summerfallow rotation. Looking at the knolls, midslopes and valleys of the hills, the group measured a number of things including organic carbon, aggregate stability, soil moisture and infiltration rates.
The organic carbon content of the soils was measured to a depth of 0 - 10 cm. The zero tilled field contained a significantly greater amount of organic carbon at all slope positions, including the knoll, than the conventional tilled field. In terms of soil aggregate stability, the knoll in the zero tilled field had larger and more stable soil aggregates than did the conventional tilled field.
Soil infiltration rates were measured in the fall of 1995 and again in the spring of 1996. In both seasons, the knolls in the zero tilled field allowed greater water infiltration than did those in the conventional tilled field.
While continuously cropping and zero tilling brought a number of benefits to all the slope positions, these benefits were more pronounced on the knolls. Sapsford says, "On our farm and some of the neighbour's farms where direct seeding and continuous cropping have occurred for a number of years, there's been an overall yield increase in each field. We think that's because the knolls are now producing like the rest of the field."
As tight profit margins continue to plague prairie agriculture, enhancing the productivity of every acre becomes increasingly important. Bare, eroded knolls are no longer standard features of hilly farms. Well planned crop rotations in a direct seeded system can ensure the knolls regain and retain their productivity.