ISSUE #367

367 - Crop Rotation Nitrogen Management Options For Sugarbeets

8-1-1999

Shareholders have known for a long time that nitrogen management is vitally important to producing a high yielding, better quality, and highly profitable crop. In the past 5-7 years new technology tools for achieving a higher yielding top quality crop have been developed. These tools include grid soil testing, soil sampling based on topography or color of sugarbeet canopies. More recently development of crop management zones based on crop canopy development during the rotation have proven very successful. Depending on the situation one or more of these tools have a place in sugarbeet grower fertility management. Lets look at an example of the uses of these management options in a three-year crop rotation.

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Year 1 - Sugarbeets: When yield and quality data are received after harvest from the factory, the current nitrogen management practices on the field should be evaluated. If the sugar percentage of the field was in the top 25% with good yield, the nitrogen management plan you are following is doing the job. If the field was below factory average for sugar percentage, with variable yield across the field, the current nitrogen practices need to be improved, starting with the very next crop. A photo or satellite image of the sugarbeet canopy in late August or September should be obtained from your agriculturist. The dark green areas of the field have large amounts of nitrogen stored in the sugarbeet canopy that won’t be measured by any soil test right after harvest. The sugarbeet tops in these dark green areas will break down and provide large amounts of nitrogen for the next several crop years. University research has shown that lower rates of nitrogen fertilizer can be applied to the areas of the field that had dark green sugarbeet tops with no yield loss in the next crop. A full rate of nitrogen fertilizer should be applied to the areas of the field that had a yellow sugarbeet canopy. Research from North Dakota State University can be used to determine the amount of nitrogen required for various areas of the field. The goal is to prevent areas of the field which already have too much nitrogen from being over fertilized, while applying enough on the rest of the field to produce optimum yields. Soil testing for %OM, P,K,Zn, S etc. for the next years crop is still recommended. Your agriculturist will have satellite imagery and zone maps available for your use.

Year 2 - Wheat/Corn/Beans: (One year after beets) Following the harvest of wheat or corn, separate nitrogen soil tests should be conducted in the areas/zones established in the sugarbeet canopy the previous year. University research has shown that areas of the field that had dark green sugarbeet tops two years earlier, often have high soil nitrogen levels for many years. By soil testing these zones separately, each zone can be fertilized with the correct amount of nitrogen fertilizer for the next crop. It is especially important to prevent areas in the field, which already have too much nitrogen from being over fertilized in the years between sugarbeet production. If soybeans are grown the year after sugarbeets, a soil test will not be as useful in determining how much nitrogen will be available to the next crop. Zone testing will help to not over fertilize dry beans and cause white mold.

Year 3 - Wheat/Barley: (Two years after beets) Following harvest of the wheat or barley. One option is to get separate nitrogen soil tests from each zone established in the sugarbeet canopy from two years earlier. Many times the areas with dark green sugarbeet leaves will still have high soil nitrogen levels. Another option for gathering more detailed evaluation would be to grid test the field in 2-5 acre areas (fields should be screened for high soil nitrate levels before grid soil sampling begins). A third option is to collect 3-5 separate soil samples in the field based on a very accurate topography map of the field. Research has shown there can be a strong relationship between topography and soil nitrogen levels. The information gathered from one of these soil testing methods will provide a base of information for variable rate application of nitrogen fertilizer prior to planting sugarbeets. Satellite images from the two previous crops or all three years can often serve as the best guide to soil sample and fertilize beets in year 4.

Other Uses of Satellite Imagery

Field Drainage - Many farmers have experienced serious yield losses due to standing water in their fields. Excess standing water causes problems like delayed field operations, root rots, denitrification losses of fertilizer and ultimately yield losses. Correcting field drainage problems improves productivity of land far beyond the year drainage is improved. The Figure 1 is a satellite image of a field with serious areas of crop drownout and water damage. Jack Call, East Grand Forks Agriculturist and the grower used this image to pinpoint the most effective way to eliminate drainage problems in this field.

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Spray Drift - Satellite images can help pinpoint the extent of crop damage to sugarbeets in a field. This may lead to more equitable insurance settlements for crop loss.

Soil Sampling Zones - Using satellite images will refine ability to define soil-sampling zones. Fields too wet to plant this spring have had differential leaching and denitrification after heavy rains. Use satellite images of previous crops on these fields to pinpoint sampling zones to best fertilize them for the 2000 crop.

Grower Idea Contest Entries Needed

Contact your agriculturist to get assistance in documenting new ideas suitable for entry in the 1999 contest. Take pictures and make notes now. Share your ideas with fellow growers so everyone benefits.

“Remember The 120 Or Less”