Impact of tillage management and landscape on nitrogen availability in cereal-fallow cropping systems

he purpose of this study was to examine the long- and short-term effects of adopting no-till fallow management practices on soil nitrogen (N) dynamics in southern Saskatchewan. The hypothesis tested was that landscape and environmental conditions have a greater impact on N turnover and availability than elimination of tillage.;Assessment of the effect of small-plot long-term (12 yr) zero-till, minimum tillage and conventional tillage practices established on a level landscape in the Dark Brown soil zone near Saskatoon, revealed no significant differences in organic C and N and available N in the top 15 cm. Nutrient uptake and yield of spring wheat was not significantly different among tillage treatments compared. These findings indicate that reduced and no-till fallow have relatively little impact on soil N availability and yield where soil erosion is not a factor.;Across the landscape, lack of incorporation of crop residue into the soil appeared to contribute to the same or slightly higher amounts and supply rates of nitrate in the no-till compared to conventional fallow. Lack of soil disturbance in chemical fallow does not appear to result in reduced N mineralization from soil organic matter and crop residue. At the landform scale, footslope (FS) and level (LE) positions exhibited greater fluctuations coupled with higher ;In 1995, the effects of chemical fallow management on N availability to the subsequent cereal crop were assessed by (i) crop N uptake and yield and (ii)...