**2.3 Statistical analysis**

56 Oilseeds

automated combustion LECO carbon analyzer. Soil available P and K were extracted by modified Kelowna method (Qian et al., 1994). Soil available N was calculated as the sum of NO3-N + NH4-N. Both forms of inorganic N were extracted with 2 M KCl (Keeney and Nelson, 1982) and measured by automated colorimetry. Soil available S was extracted with 0.001 M CaCl2 solution and measured by automated colormetry (Qian et al., 1992). The fertilizer phosphorus source used was conventional commercial fertilizer grade granular monoammonium phosphate MAP (12-51-0). The sulfate source used was fertilizer grade prilled ammonium sulfate (NH4)2SO4 (21-0-0-24). The *Brassica* species/cultivars selected for this study are listed in Table 2. Among the 12 selected cultivars, four different categories of canola were included: open pollinated (OP) and hybrid *napus* (also termed "Argentine" canola) (HYB), *rapa* (also termed "Polish" canola), and *juncea* (sometimes termed "mustard canola"). Although not currently grown on a large commercial scale, *B. carinata* and *C. sativa* are currently under development as new oilseed crops with similar attributes to canola and

Plants were grown in plastic trays (52cm x 26cm x 6cm) containing 5.4 kg of uniformly mixed, air-dried soil at 20 degrees C. The soil in each tray was levelled to a height of 5cm over the individual rows and packed. Six 20cm x 2.50cm x 1.25cm seed-rows were created in the trays using a seeding tool. The crops were seeded using a seed quantity per unit area in the row that is equivalent to a seeding rate of approximately 10 kg ha¯¹. The seeding tool used creates a seed bed utilization of approximately 15%, in which 15% of the total seed bed area is used for placement of seed and fertilizer in rows. This seed bed utilization is typical of the wide row spacing, narrow opener seeding tool configurations commonly used for seeding oilseeds in the northern Great Plains today. Sixteen seeds were seeded in each row

The fertilizer was passed through a 2mm sieve to provide uniform granule size and then spread uniformly down the seed-row with the seed. During germination, trays were kept under constant light and regularly watered to maintain soil moisture at 100% water holding capacity for the first two days and ensure germination, and then reduced to 80% of field capacity to maintain soil moisture for seedling growth. Emergence counts were taken every two days after seeding until 14 days after seeding (DAS) when plant counts were constant and no additional emergence was observed. Plants were harvested 14 DAS. Plant biomass samples were washed in deionized water after cutting at the soil surface and oven-dried at

Six treatments consisting of an unfertilized control and five rates of seed-placed S (10, 20, 30, 40 and 50 kg S ha-1), applied as ammonium sulfate (AS 21-0-0-24) were applied in combination with three rates of seed-placed P205 (0, 15 and 30 kg P2O5 ha-1), applied as

The *B*. species/cultivars were designated as main plots, S rates as subplots and P rates as sub-subplots within the trays and were arranged in a randomized complete block design with four replications. Nitrogen was applied at 10, 20, 30, 40, 50 kg N ha-1with the ammonium sulfate alone, and with 15 kg P2O5 ha-1 as well as 30 kg P2O5 ha-1 in the seed-row.

were therefore included in the study as well.

**2.2 Laboratory study** 

at a uniform depth of 1.25cm.

45°C for 3 d to a constant weight.

monoammonium phosphate (MAP 12-51-0).

Main and interaction effects of *Brassica* cultivars and ammonium sulfate, alone and in combination with monoammonium phosphate, were determined from analysis of variance (ANOVA) using the GLM procedure in SAS (SAS Institute, 2008). Least significant difference (LSD 0.05) was used to determine significant differences between treatment means.
