Nitrogen rates for sugarbeets vary depending on previous crops
Optimum nitrogen recommendations for Michigan sugarbeets will range from 70 to 150 pounds per acre based on previous crops.
Nitrogen is one of the most important nutrients in sugarbeet production. Over applications of nitrogen will result in low quality beets by lowering sugar content and increasing impurities. Not applying enough nitrogen will reduce tonnage and recoverable white sugar per acre. Optimum recommended rates will vary depending on both the amount of residue and type of previous crop. If manure has been applied, soil nitrate testing is highly recommended to predict nitrogen availability and recommendations.
Nitrogen research conducted by Sugarbeet Advancement and Michigan Sugar Company has produced some general recommendations that growers can follow to optimize yield and quality. The highest rates of nitrogen are generally used when following high residue crops such as corn or wheat with no legume cover crop. Residues in these crops can actually tie up nitrogen and leave it unavailable until residue is broken down. Nitrogen application rates of 120 to 150 pounds per acre rates generally are optimum. It is very important in high residue situations that a significant portion of nitrogen be applied up front by either pre-plant, 2-by-2 starter or a combination.
When following low residue legume crops such as dry beans or soybeans, nitrogen rates can be reduced. Generally, rates of 90 to 120 pounds per acre work well. Sugarbeets planted following a wheat or clover plow down can further reduce nitrogen rates. Clover is a legume that can supply some additional nitrogen and is excellent in improving soil health. Rates of 80 to 100 pounds nitrogen should be adequate.
Nitrogen applications should be applied so that the majority, if not all, of the nitrogen is available early to the plant. If some of the nitrogen is applied by sidedress, these applications should be made relatively early as well. Normally, sidedress applications should be made by late May or early June.
Ideally, when we get into September the sugarbeet plant should be running out of soil nitrogen and redistributing nitrogen from the leaves to the roots. It is desirable at harvest time to have the leaves a lighter green or off-color for best quality. Sugarbeet fields slated for early harvest or fields with thin stands should have lower nitrogen rates compared to full season good population beets.