Bly A., H.J. Woodard, and D. Winther
Methods:
An experiment was conducted at Aurora SD on the Crop Improvement Farm to investigate the effect of applied N on fifteen hard red spring wheat varieties. The fertilizer N treatments consisted of either a control N treatment in which no fertilizer N was applied (check) or a recommended N rate (100 lbs/a) as UAN (liquid 28-0-0) broadcast on the surface prior to planting to support a yield goal of 50 bu/a. Chloride was broadcast applied to all plots prior to planting at 55 lbs Cl-/a as liquid tire fill. The varieties were no-till seeded on April 21, 1998 into soybean residue and 30 lbs P2O5/a was applied with the seed as 0-46-0. Plots were 5' wide and 32.5' long and all varieties were seeded at 1.2 million pure live seeds/a. Varieties and the N treatments were randomized and replicated four times in a factorial design. A tank mix combination of Hoelon (2.66 pts/a), Buctril (1 pt/a), and MCP-Ester (1.25 oz/a) was sprayed on May 26, 1998 to control grasses and broadleaf weeds. Lorsban was sprayed on July 2, 1998 at 1 pt/a for grasshopper control. Folicur was applied at 4 oz/a on June 19, 1998 for plant and head disease control. Early growth samples were harvested on May 23, 1998 from one meter of row at early jointing stage (Feeke’s stage 5-6) and soft dough stage (Feeke’s stage 11.3) on July 23, 1998. Plant material was dried, weighed, culms counted, and stored for nutrient analysis. Plots were harvested with a plot combine on August 11, 1998. Grain yield and moisture was determined from on-board scale and moisture blade. Grain test weight and protein was determined with standard measuring techniques and NIR spectroscopy. Statistical analysis were made by using SAS.
Results and Discussion:
Grain test weight, protein, and yield were all influenced by variety and N treatment (Table 1). The Variety by N treatment interaction had a significant effect on grain test weight but not on grain protein or yield (Table 1). Varietal differences of the dependent variables were expected since each variety has an unique set of growth characteristics and yield capabilities. Varietal grain protein ranged from 10.3 percent with Nordic to 12.4 percent with Vance. Varietal grain yield ranged from 35.9 bu/a with Prospect to 43.6 bu/a with Krona. The recommended N rate gave significantly higher grain test weight, protein and yield (Table 1). All 15 varieties had significant N treatment responses with grain protein and yield (Table 2). The recommended N rate always gave higher grain protein and yield (Table 2). The greatest grain protein response to applied soil N was from Butte-86 at 3 %. The greatest grain yield response to applied soil N was from Russ at 13.7 bu/a. Grain yields were considered to be lower than normal due to dry growing conditions . However; the reduction in crop growth potential from reduced precipitation did not overshadow the soil N treatment effect.
Conclusions:
Application of recommended soil N significantly increased grain test weight, protein and yield. All 15 varieties tested had significantly higher grain protein and yield due to application of recommended soil applied N.
Acknowledgment:
This project was partially funded by the SD Wheat Commission and the SD Ag. Experiment Station.
