Steppuhn, H., Acharya, S. N., Iwaasa, A. D., Gruber, M. and Miller, D. R. 2012. Inherent responses to root-zone salinity in nine alfalfa populations. Can. J. Plant Sci. 92: 235–248. Alfalfa productivity can be enhanced by growing crops from cultivars tolerant of root-zone salinity. Rangelander, Keho, Bridgeview, Halo, CW054038, CW064027, Rugged, Bullseye and TS4002 alfalfa plants (respectively designated Ra, Ke, Br, Ha, C8, C7, Ru, Bu and T4) were grown in sand tanks irrigated with nutrient-sulphate solutions averaging 1.53 (nutrients only), 8.03 and 15.61 dS m−1 in electrical conductivity. Except for Br and C7, seedlings emerged equally under the 1.5 and 8.0 dS m−1 treatments, but decreased in the 15.6 dS m−1 treatment by percentages ranging from 3.1 through 29.5. Average shoot biomass among the populations respectively decreased by 49.6, 43.6 and 37.6% in the 1st, 1st+2nd, and 1st+2nd+3rd harvest-cuts as salinity increased from 1.5 to 8.0 dS m−1 and by 80.1, 73.2 and 67.1% from 1.5 to 15.6 dS m−1. At 1.5 dS m−1, the C7 plants consistently produced more shoot biomass than the T4, Bu, Ha, Ru, Ra, or Ke plants. At 8 dS m−1, the relative yields of the Ha plants (scaled by their 1.5 dS m−1 production) exceeded those from the other populations, although the Ha plants produced no greater actual shoot biomass than the C7 or the C8 plants.

Kröbel, R., Lemke, R., Campbell, C. A., Zentner, R., McConkey, B., Steppuhn, H., De Jong, R. and Wang, H. 2014. Water use efficiency of spring wheat in the semi-arid Canadian prairies: Effect of legume green manure, type of spring wheat, and cropping frequency. Can. J. Soil Sci. 94: 223–235. In the semi-arid Canadian prairie, water is the main determinant of crop production; thus its efficient use is of major agronomic interest. Previous research in this region has demonstrated that the most meaningful way to measure water use efficiency (WUE) is to use either precipitation use efficiency (PUE) or a modified WUE that accounts for the inefficient use of water in cropping systems that include summer fallow. In this paper, we use these efficiency measures to determine how cropping frequency, inclusion of a legume green manure, and the type of spring wheat [high-yielding Canada Prairie Spring (CPS) vs. Canada Western Red Spring (CWRS)] influence WUE using 25 yr of data (1987–2011) from the “New Rotation” experiment conducted at Swift Current, Saskatchewan. This is a well-fertilized study that uses minimum and no-tillage techniques and snow management to enhance soil water capture. We compare these results to those from a 39-yr “Old Rotation” experiment, also at Swift Current, which uses conventional tillage management. Our results confirmed the positive effect on WUE of cropping intensity, and of CPS wheat compared with CWRS wheat, while demonstrating the negative effect on WUE of a green manure crop in wheat-based rotations in semiarid conditions. Furthermore, we identified a likely advantage of using reduced tillage coupled with water conserving snow management techniques for enhancing the efficiency of water use.

Kröbel, R., Campbell, C. A., Zentner, R. P., Lemke, R., Steppuhn, H., Desjardins, R. L. and De Jong, R. 2012. Nitrogen and phosphorus effects on water use efficiency of spring wheat grown in a semi-arid region of the Canadian prairies. Can. J. Soil Sci. 92: 573–587. Water use efficiency (WUE) has often been analyzed for semiarid environments, but fallow-containing cropping systems were assessed inappropriately. Further, these short-term studies are unlikely to correctly assess weather variability impacts in such environments. We assessed the impact of fertilizer N and P on water use efficiency (WUE) and precipitation use efficiency (PUE) of spring wheat (Triticum aestivum L.) from a 39-yr long-term crop rotation study in semi-arid southwestern Saskatchewan. In the rotation experiment, continuous wheat (Cont W) with N+P or P fertilizer only, and fallow-wheat-wheat (F-W-W) with N+P, P only, or N only were studied. We calculated WUE using: (i) Yield (Y)/[water use (WU)/potential water use (PET)]; (ii) Y/WU; (iii) Y/WU with a fallow phase element added; and (iv) Y/harvest-to-harvest precipitation (PUE). The WUEs in the rotation experiment were generally greater for treatments with N+P fertilizer, and greatest after an increase of N application coupled with favourable soil water conditions in the final decades of this study. In cases (i) and (ii), WUE for F-W-W was greater than for the Cont W-treatment. In case (iii), the WUEs were 5.7, 4.5, 3.9, 3.6, and 3.6 kg ha−1 mm−1 water for Cont W (N+P), Cont W (P), F-W-W (N+P), F-W-W (P), and F-W-W (N), respectively. For PUE [case (iv)] the values were 4.0, 3.1, 3.4, 3.0, and 2.9, respectively. We concluded that case (ii) was most appropriate for continuous cropping and case (iii) for systems including fallow, while case (iv) was usable in general.