A University of Nebraska study says that banding nitrogen with strip-till has little effect on sugarbeets vs. broadcasting it.
Researchers for the 2006-07 study wanted to measure the impact of strip-tilled application of nitrogen vs. broadcasting to determine the effect on stand, yield, sugar, SLM and nitrogen-use efficiency.
They also wanted to see if there was an effect on soil-sampling recovery of residual nitrate.
Because of the root architecture of sugarbeets, the question many producers have is whether strip-till placement of nitrogen might be more efficient than conventional broadcast application of nitrogen.
Improved efficiency could mean less nitrogen or improved quality. However, limited data is available comparing conventional nitrogen placement vs. deeper-placed nitrogen in strip-till.
A lack of nitrogen results in sugarbeet productions results in reduced root yield while excess nitrogen causes a decrease in sucrose content and an increase in SLM (sugar loss to molasses).
All Plots Strip-Tilled
In this study, nitrogen rates for sugarbeets were 0, 35, 70, 105, 140, and 175 pounds in 2006. In 2007, a nitrogen rate of 210 pounds per acre was added. Researchers used a Schlagel Mfg. strip-till rig for application. To avoid confounding tillage or ripping effects with nitrogen-application methods, all plots were strip-tilled.
The strip-till nitrogen treatments for sugar beets were applied 1 to 2 days before planting (late April or early May) using UAN (32-0-0). The shanks were set to a depth of 11 inches and two injection points were at 4 inches and 10 inches below the soil surface with half of the nitrogen being applied at each depth.
The broadcast-nitrogen treatments received 35 pounds of nitrogen per acre before planting (except the check) with remaining nitrogen applied in late June as urea (46-0-0) followed by a light irrigation.
Nitrogen rates for sugarbeets were set so the highest rate would be sufficiently high to provide excess nitrogen to determine effects on sugar and SLM.
With the planting and replanting delays, inclusion of the lower rates turned out to be important as researchers fully expected a much lower yield level (nearer 20 tons per acre) due to the late replanting.
Seedling counts a week after planting (2006 and 2007) showed stands as low as 30,000 to 40,000 plants per acre (seeding rate 56,000 per acre). Plant stands 2 weeks after replanting ranged from 47,000 to 50,000 plants per acre each year and there were no nitrogen rate or method treatment effects.
Nitrogen Rate Differences
The only significant treatment effect both years was nitrogen rate. Nitrogen application methods had no significant effect on any parameter measured. There was a tendency for tare and SLM to be somewhat lower with strip-till applied nitrogen versus broadcast both years.
Because there was not a significant method effect, nitrogen rate effects were averaged across application methods. Nitrogen rate increased yield up to a nitrogen rate of 105 pounds per acre in 2006 and 70 pounds per acre in 2007.
Sugar content showed the usual decline with increasing nitrogen rate, but sucrose amount was maximized near the 105-pound-per-acre rate in 2006 and 70 pounds per acre in 2007. Increasing nitrogen rate significantly increased sugar loss to molasses (SLM) and decreased sugar content.
There is some evidence that strip-till may have an advantage over broadcasting nitrogen (somewhat lower SLM, tare, higher sucrose in 2007), but more site years and locations will be required to determine if that difference is truly significant.
For now, strip-till is a good option for sugarbeet production requiring less energy than plowing.
Without a tillage effect, however, there has not been a significant difference in nitrogen application method, which suggests that those still using conventional broadcast aren't affecting yield or quality as long as they have a correct nitrogen rate.