The adaptation of seven broadleaf crops to the dry semiarid prairie

To develop diversified cropping systems for the dry semiarid prairie, the adaptation of alternative crops must be known. This experiment compared the adaptation of seven pulse and oilseed crops—desi chickpea (Cicer arietinum L.), dry bean (Phaseolus vulgaris L.), dry pea (Pisum sativum L.), lentil (Lens culinaris L.), mustard (Brassica juncea L.), safflower (Carthamus tinctorius L.), and sunflower (Helianthus annuus L.) — with spring wheat (Triticum aestivum L.), using two tillage practices — no-till and minimum tillage, including both fallow and wheat stubble-field phases. It was conducted near Swift Current, SK 1992–1996, and on a commercial farm near Congress, SK 1994–1995. Tillage system had no consistent effect on plant densities, which were generally adequate. Mustard, desi chickpea, dry pea and lentil required fewer degree days (5°C base) to reach anthesis, compared with wheat, while safflower and sunflower required more than wheat. Dry pea generally matured sooner than wheat, while lentil and mustard matured earlier than wheat only in years when near normal climatic conditions occurred. All other crops generally matured later than wheat. Safflower required an additional 400 degree-days and as a result presents considerable production risk in the semi arid prairies. Dry pea grain yields averaged 103% of wheat when grown on fallow and 135% of wheat when grown on stubble. Chickpea, lentil and dry pea yielded 76%, 77% and 90%, respectively, of their fallow-field yields when grown on stubble, indicating that the pulse crops have excellent potential for intensifying cropping systems in the dry semiarid prairie by replacing summerfallow in crop rotations. In contrast, wheat and mustard grown on stubble yielded only 66 and 61%, respectively, of fallow-field yields, suggesting they are not as well suited for stubble-cropping as the pulse crops. Low and highly variable yields were observed for safflower, dry bean and sunflower in both field-phases, although the yields from dwarf hybrid sunflower in the latter 2 yr of the study appeared promising. Low seed N concentration in wheat indicated yields were limited by soil-available N in most years, due to the generally wetter than normal growing seasons encountered during this study. The mean N yield (seed N concentrat ion × grain yield) of dry pea was double that for chickpea and lentil, indicating that dry pea fixed the greatest amount of atmospheric N2. Water-use efficiency for dry pea averaged 9.4 kg ha–1 mm–1 compared with 7.4 kg ha–1 mm–1 for wheat. Dry pea, chickpea, lentil, mustard and sunflower have good potential for diversifying cropping systems in the dry semiarid prairie. Key words: Oilseeds, pulses, adaptation, semiarid prairie, tillage systems, water-use efficiency