Embedded Files
Experimental Location
Figure 4: Image4 showing the location of the experiments in this study. These experiments were conducted in Alberta at Barrhead (2019), Beaverlodge (2021-23), Edmonton (2019-2023), Lethbridge Dry (2020-23) and Irrigated (2019-23), and Vermillion (2020-2023). In Saskatchewan they were located at Scott and Indian Head (2019-2023).
Experimental set up
Experiment I consisted of side/mid-row banding six N forms at four different rates. Experiment II consisted of applying five N forms at three different timings, using two CWRS wheat cultivars. Both experiments had one control plot per cultivar per replicate and were arranged in a random complete block design with four replicates.
Overview of Experiment I
(Two Factors)
•N forms
•Agrotain (urease inhibitor)
•SuperU (nitrification and urease inhibitor)
•Instinct impregnated urea (nitrification inhibitor)
•Polymer-coated urea (ESN)
•NBPT-DMPSA (urease and nitrification inhibitor)
•Untreated Urea
•N rates
•60 kg N ha-1 all side or mid-row banded at planting
•120 kg N ha-1 all side or mid-row banded at planting
•180 kg N ha-1 all side or mid-row banded at planting
•240 kg N ha-1 all side or mid-row banded at planting
Overview of Experiment II
(Three Factors)
CWRS Cultivar
•AC Stettler
•AAC Viewfield
N form
•Agrotain (urease inhibitor)
•Instinct impregnated urea (nitrification inhibitor)
•SuperU (nitrification and urease inhibitor)
•Polymer-coated urea (ESN)
•Untreated Urea
Timing and Placement
•All N banded at planting
•30 % banded at planting: 35% @ Feekes GS4 (BBCH 30); 35% @ Feekes GS10 (BBCH 45)
•65 % banded at planting: 35% @ Feekes GS10 (BBCH 45).
Table 1: Diagram of the experimental design layout for experiment I. Colour codes are representative of the combination of factors 1 and 2 per individual plot. There are 25 plots per replicate.
Table 2: Diagram of the experimental design layout for experiment II. Colour codes are representative of the combination of factors 1, 2 and 3 per individual plot. There are 32 plots per replicate.
The timing and placement factor of experiment II involves broadcasting fertilizer at certain growth stages. Figure 5 below, illustrates the sequential Feekes and Zadoks growth stages that wheat will go through and what stage fertilizer will be applied. For the timing and placement factor of experiment II, N fertilizers are broadcast at Feekes 4 and 10 stages (Zadoks 30 and 45).
Figure 5:Image5 of sequential cereal growth based on Feekes (GS) and Zadoks (BBCH) scales.
Figure 6: Image of a John Deere 5075M tractor seeding experiment II at the Lethbridge dry-land site with a no-till air drill using Conserva pak openers at 9" row spacing (Tripper: R. Dyck; Driver: W. Taylor).
Plots
Plot size varied by location and were grown with conventional agronomic practices. In Lethbridge, 10m plots were sown with a no-till air drill using Conserva pak openers at 0.2413m (9") row spacing to achieve 400seeds/m2. A mixture of tebuconazole, prothioconazole and metalaxyl (Raxil Pro) was used for seed treatment at a rate of 325ml/100kg of seed prior to planting. Appropriate herbicide and fungicide applications were made as needed with recommendations from the Alberta Crop Protection Guide. A blanket application of the plant growth regulator chlormequat-chloride (Manipulator) was applied to all plots at BBCH 30-32. Experiment II used a plot sized Valmar air delivered broadcaster for the two in-crop N applications. Plots were combined with a Wintersteiger Delta plot combine at harvest maturity. Yield was determined by weighing harvested grain based on the harvested area. Grain protein content was measured using a Foss Grainspec (NIR) grain analyser.
Figure 7: Image of a plot sized Valmar air delivered fertilizer broadcaster towed behind an All-Terrain-Vehichle (ATV).
Figure 8: Image of a Wintersteiger Delta plot combine combining experiment I at the Lethbridge dry-land site (Bagger: K. Van Staalduine; Driver: S. Simmill).
Statistical Analysis
Data for each experiment were analyzed separately using R (R Core Team, 2021). Since we're dealing with multi factored experiments, multi factor ANOVA (analysis of variance) tests were used to determine the significance of main effects (factors) and interactions. Multi factor ANOVA's are used to to determine if more than one numeric or categorical predictor variable explains variation in a numeric outcome. Multi factor ANOVA's assume normality in their data distribution and homogeneity of variance. R's contrast function was also used when significant interactions were present to further elaborate ANOVA results. The compact letter design (CLD) function was also used to visually distinguish significant groups in certain graphs. Effect size statistics were completed to determine pre-determined yield gains based on probabilities. Significance was declared at p=0.05.
Page updated
Report abuse