Adverse Effects of Cropping Systems in Saskatchewan on lentil Yield.

No-tillage (NT) systems are well adapted to the western Canada farming systems. Legumes are replacing the summer fallow to improve the sustainability of cropping system by maximizing water and nutrient use efficiency, N fixation and weed control. However, a trend of reduced in lentil yield during the past few years is … in Saskatchewan. Later maturity in the presence of readily available N in the NT systems, especially in the Black soil zones and in wet years, is the most widely explanation for yield reduction in lentil. We compared, plant growth, N accumulation and yield of lentil in two fields subjected to long (>20 yrs) and short-term (<10 yrs) NT along with a history of legumes in their rotations.  Despite the higher amount of available N in the long-term NT field, plants grown in the short-term site accumulated more biomass and N and, as a result, produced more yield in both years (2006 and 2007). Harvest index and nodes per plant were statistically similar for both short and long-term NT sites. Lentil was then grown in a growth chamber on soil taken from the same fields with canola stubble in fall. Soils had been previously treated with the herbicide Lontrel in spring.  Seedlings germinated in both soils showed herbicide injury symptoms, but the injury was more obvious in plants grown in long-term NT than short-term. Plants from short-term NT had significantly higher N and P content, more nodules and greater nodule mass.  Although part of the yield reduction related to the residual effects of herbicides in both soils, long-term presence of lentil in rotation could negatively impact plant production. In comparison of several soils with and without background of legume in the same study, lentil had better performances in the soils with no history of legume.