Nitrogen considerations for sugarbeets following manure

Starter nitrogen and pre-sidedress soil nitrate testing are important when planting sugarbeets in fall manure-applied fields.

Research conducted by both Michigan Sugar Company and Michigan State University Sugarbeet Advancement program (SBA), has shown the importance of early season nitrogen availability on improving beet growth and yield. This research has been conducted in fields with no recent history of manure. In 2010, research was conducted by SBA in a fall applied manure field that showed similar results.

In the fall of 2009, dairy manure was applied at 10,000 to 12,000 gallons per acre to a field after corn silage harvest. Sugarbeets were planted in the spring of 2010. Trial treatments included no additional fertilizer, the addition of approximately 41 pounds of nitrogen by 2x2 starter only, the addition of 45 pounds of nitrogen by sidedress only, the combination of both treatments for 86 pounds additional N, and the growers normal practice of 25 pounds by starter and 60 pounds by sidedress. The trial averaged 29 tons per acre and 19.1 percent sugar.

The results showed that the check treatment of no additional nitrogen provided a net return of $1,541 per acre. The highest net return of $1,642 was the treatment that had only 41 pounds of nitrogen per acre in the 2x2 starter. When nitrogen was applied as 2x2 and sidedress, for a total of 86 pounds, the net return was $1,596 per acre. The treatment of 45 pounds nitrogen by sidedress had a net return of $1,543 per acre. The grower’s normal practice provided the lowest return of $1,501.

In this trial, the largest influence on the net return was the difference in beet quality, not tonnage. The starter only treatment provided the highest tonnage, but only the check was significantly lower. Beet quality was negatively affected by the sidedress applications. This was probably primarily due to a fairly late sidedress application date of June 16.

Beet growers that apply manure have a dilemma when it comes to sidedress applications. There are large differences in manure nutrient content, nutrient loss and release of nitrogen from organic matter breakdown. Therefore, sidedress applications should be based on pre-sidedress nitrate testing. If a grower waits for soils to warm up enough to provide accurate levels of the soils available nitrogen, they may be already sidedressing later than nitrogen should be applied to beets. To avoid a negative effect on quality, sidedress applications to beets should be made early after emergence. This application would preferably be when beets are somewhere between 2 to 6 leaf stage, which is likely between mid and late May.

The results of this trial would indicate that fall manure applications could supply a large part of the sugarbeet nitrogen needs. It would also indicate that early season nitrogen from fall applied manure may not be readily available and 40 pounds of nitrogen in the 2x2 starter could supply that early need. It is recommended that growers should then utilize a pre-sidedress nitrate test to help determine the need for additional nitrogen. This test should be done as early as soil temperatures would provide accurate results.

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