Yield, water use, and protein content of spring wheat grown after six years of alfalfa, crested wheatgrass, or spring wheat in semiarid southwestern Saskatchewan

Abstract

In the semiarid prairie of western Canada, there is renewed interest for including short durations (≤3 yr) of perennial forage in rotations with annual crops. However, there are producers who want to grow longer durations (≥4 yr) of perennial forages in rotational systems. Therefore, we assessed spring wheat (Triticum aestivum L.) yield, grain protein, and water use efficiency following 6 yr of either crested wheatgrass [Agropyron cristatum (L.) Gaertn.], or alfalfa (Medicago sativa L.), or wheat, and then 1 yr of fallow. Yield, water use, and water use efficiency were significantly lower in the first year of spring wheat production (2000) when the prior crop was crested wheatgrass or alfalfa than when it was wheat. In the second year (2001), which was a near record drought year, wheat yield and water use were significantly lower when the prior crop was alfalfa than when it was grass or wheat. From 2002 to 2005, there were no consistent differences in water use, water use efficiency, or yield of wheat due to the prior perennial crop. Wheat grain protein concentration was significantly higher following alfalfa compared with following crested wheatgrass or continuous spring wheat from 2000 to 2005. This effect was attributed to the higher N-supplying power of the soil following alfalfa. Soil water content below the rooting depth of most annual crops (≥120 cm depth) was reduced by the prior alfalfa crop, and there was no evidence from 2000 to 2005 that soil water recharge was occurring below the 150-cm depth. Key words: Semiarid prairie, alfalfa, grass, spring wheat, yield, protein, water use