Optimum sugar beet production in Minnesota and North Dakota is built on a sound fertility program. There is a financial reward for delivering a high quality product to the factories. The quality of the harvested sugar beet is affected by the fertilizer that is supplied.
Nitrogen is the most important nutrient when planning a fertilizer program for sugar beet production. Nitrogen fertilization promotes vigorous early-season growth thereby reducing the number of days to canopy closure. Early closure allows the sugar beet to make better use of sunlight and more sugar is produced. Excess nitrogen at or near the end of the growing season reduces sugar beet quality by reducing sucrose concentration. The highest quality sugar beet is produced when nitrogen deficiency occurs late in the growing season (about 6 weeks prior to harvest).
The amount of nitrogen fertilizer suggested should be adjusted for the amount of NO3 --N measured in the soil profile to a depth of 4 ft. The nitrogen fertilizer guideline will depend on the location that the sugarbeet is grown. For the Minn-Dak and American Crystal growing areas, a total of 130 lbs per acre as soil test NO3 --N in the surface 4 ft. plus fertilizer N is needed. If a grower is unable to get a soil sample to 4 ft and if there are small amounts of NO3 --N at a depth of 2 to 4 feet are suspected, a soil test to a depth of 2 ft. can be used. The total N would be 110 lb per acre soil test NO3 --N plus fertilizer N. In the Southern Minnesota Beet Sugar Cooperative growing area, the amount of NO3 --N for a 4 ft soil test and fertilizer should be 100 lbs per acre and for a 2 ft. soil test, the total should be 80 lbs per acre.
Results of various field research projects have shown that all nitrogen fertilizers will have an equal effect on production if applied in a way that loss of any nitrogen is minimized. Fall application of liquid nitrogen (28-0-0) and ammonium nitrate (33-0-0) is discouraged. Split applications of nitrogen may be wise for sugar beets grown on sandy soils. The applications should be scheduled so that the last application takes place before July 1. For soils that are not sandy, the split applications have not been superior to a single pre-plant application and have caused a decrease in the quality of the crop.
Phosphate fertilizer, when needed, has increased production without a significant effect on quality. The guidelines for phosphate use are summarized in Table 1. The suggested rates are for a broadcast application. Minnesota research has shown that banded applications on the seed are very efficient. If this seed placement is used, the suggested rate is 15 lb P2O5 per acre. This can be supplied as 3 gallons ammonium polyphosphate (10-34-0).
Table 1. Phosphate guidelines for sugar beet production.
|Phosphorus (P) Soil Test|
|Bray||Olsen||Phosphate to Apply|
|— ppm —||— lb P2O5/acre —|
|21 +||16 +||0|
Suggestions for potash use are based on the results of a soil test and are summarized in Table 2. This nutrient is not a major concern in sugar beet production because a large majority of the soils supporting this crop are natively high in potassium. Potash fertilizer can have a negative effect on germination if placed on or too close to the seed. Therefore, broadcast applications of potash are suggested.
Table 2. Potash guidelines for sugar beet production.
|Potassium (K) Soil Test||Potash to Apply|
|— ppm —||— lb K2O/acre —|
In Minnesota and North Dakota growing areas, the use of sulfur, zinc, magnesium, calcium, boron, iron, copper, and manganese has had no effect on either the yield or the quality of the sugar beet crop. Therefore, the use of these nutrients is not needed.
Those who choose to place fertilizer with the seed should use caution. Applying more than 5 lb. per acre of N + K2O in contact with the seed can reduce emergence and subsequent stands. The use of 10-34-0 at rates less than 4 gallons per acre in 22 inch rows has not been harmful. The potential for reduced stand resulting from fertilizer placed with the seed increases as the moisture content of the soil decreases.