Fig. 1.

Estimated summer fallow area for (a) the prairie provinces of Canada and (b) Montana and North Dakota.

 


Fig. 2.

Illustration of (a) heavy tine harrow and (b) rotary harrow.

 


Fig. 3.

Emergence patterns of wheat stem sawfly Cephus cinctus collected from experimental plots near Lethbridge, AB, Canada, 2004–2006. Emergence over time is illustrated in Fig. 3a and emergence vs. growing degree days accumulated from 1 May is summarized in Fig. 3b. Growing degree day information was acquired from the Agriculture and Agri-Food Canada meteorological weather site, Lethbridge, AB, Canada.

 


Fig. 4.

Biplot (mean vs. CV) of harrow by seeder combinations for data collected at a study site near Coalhurst, AB, Canada, 2004–2006. The first letter of the labels indicates harrow (T = tine harrow, R = rotary harrow, and con = control– no harrowing), the following number indicates the tension for the tine harrow (5° or 20°) or the angle for the rotary harrow (25° or 45°), and the last letter indicates the seed drill configuration (D = disc drill, K23 = knife opener spaced 23 cm apart, K30 = knife opener spaced 30 cm apart, and Sw = sweep opener spaced 23 cm apart). Grouping categories: Group I: high mean, low variability (optimal); Group II: high mean, high variability; Group III: Low mean, high variability (poor); Group IV: Low mean, low variability.