Location: This farm is located near Sutherland in O'Brien County, Iowa
Figure 1: Site map
Description: The total area is approximately 32 acres of which 26 acres are used as experimental plots and the remainder as border and buffer. A total of 32 experimental plots are available which are 160 ft x 225 ft.
Drainage design: Subsurface drainage lines were installed in 2013 parallel to the long dimension through the center of each plot and on the borders between plots (80 ft. spacing). See Figures 2 and 3.
Figure 2: Drainage design
Figure 3: Example of subsurface drainage layout for four plots.
Treatments:
|
Treatment Number |
Tillage |
Nitrogen Application Time |
Nitrogen Application Rate (lb N/acre)* |
|---|---|---|---|
|
1 |
Conventional tillage** |
Fall (Anhydrous Ammonia with nitrapyrin) |
135 |
|
2 |
Conventional tillage |
Spring (Anhydrous Ammonia) |
135 |
|
3 |
Conventional tillage |
Split with variable N at sidedress (40 lb/acre of UAN at planting plus in-season adjusted rate no later than mid-vegetative growth stage) |
Yearly variable based on in-season adjusted rate |
|
4 |
Conventional tillage |
None |
0 |
* For corn plots only. The 135 lb N/acre rate is based on the Corn Nitrogen Rate Calculator output for corn following soybean in Iowa at a 0.10 price ratio.
** Fall chisel corn stalks with spring disk/field cultivate, and spring disk/field cultivate soybean stubble.