Allan Cattanach -
Sugarbeet Specialist, NDSU/U of MN., Fargo, ND
Dave Franzen - Extension Soil Specialist, NDSU, Fargo, ND
Dan Bernhardson - Agriculturist, American Crystal Sugar Co., Moorhead, MN
Dave Braaten - Agriculturist, American Crystal Sugar Co., Moorhead, MN
Recent development in new technologies have given growers the potential to increase accuracy of nitrogen management and sugarbeet profitability. About 25 percent of all sugarbeet acreage in Minnesota and North Dakota was grid sampled and variable rate fertilized in 1996. Past experiences have indicated about 70 percent of the fields grid sampled are likely to give profitable responses to variable rate fertilization. Experience in 1995-1996 has shown about 30 percent of those fields are not likely to give profitable responses to variable rate fertilization.
The purpose of these studies was to compare yield, quality and profitability of sugarbeet production using site-specific versus conventional soil sampling and fertilizer application techniques. An additional objective was to determine if nitrogen recommendations could be further refined by increasing or decreasing nitrogen application rates based on individual grid organic matter levels.
Two studies were established in grower fields at Felton and Foxhome, Minnesota. Fields were grid sampled on about a 4.4 acre grid size to determine nitrogen status at both locations and organic matter content at Felton. Headlands were not included in the studies. The conventional sampling consisted of about 30 probes in a random pattern across the field. Twelve 4.4 acre grids were sampled at each location. Six or eight soil samples per grid were taken. Soil samples were taken from 0-6", 6-24", and 24-48" depths at Felton. Samples at Foxhome were taken only from the 0-6" and 6-24" depths. Soil analysis was performed on Foxhome samples at Agvise laboratories and by Minnesota Valley Testing Labs for Felton samples.
|72 Rows Conventional Management|
At Felton 12 grids across a field were grid sampled then split into thirds (a) one-third grided and variable rate fertilization; (b) one-third grided and variable rate fertilized with organic matter adjustment; and (c) one-third conventionally fertilized.
|Organic Matter Soilection|
|Organic Matter Soilection|
Based on soil tests the Foxhome site was fertilized to a level of 150 lb/A available soil test plus residual nitrate-nitrogen. The Felton site was fertilized to a level of 120 lb/A available nitrate-nitrogen with adjustments made when 2-4' nitrogen is more or less than the 30 lb/A level. The studies were designed only to look at variable rate nitrogen application.
The field at Felton had very uniform plant populations of about 160 beets/100' of row. Plant population at Foxhome was about 150 beets/100' of row on the conventional strips as sampled by North Dakota State University scientists and 120 beets/100' of row for grid sampled and fertilized. This plant population difference probably skewed North Dakota State University sample results.
At each location North Dakota State University/University of Minnesota scientists took six ten foot long hand dug samples per grid for yield, quality, and plant population data. A total of 144 samples were taken at Foxhome and 216 samples taken at Felton. Harvest was completed the same day in the first week of October that the grower harvested the field strips at Foxhome. Harvest was completed by North Dakota State University/University of Minnesota scientists at Felton on September 30 and grower harvest completed on October 14. Quality analysis on all samples was done at the American Crystal Sugar Co. lab at East Grand Forks, Minnesota. All grower loads were delivered to the same outlying piling ground at Foxhome to reduce chances for errors.
Grid sampling gave a far more accurate estimation of total nitrogen in the 0-4' soil profile at Felton than conventional sampling, Table 1. The field conventional soil test level was 62 lb/A, 0-4'. Table 2 shows levels of available nitrate-nitrogen at Foxhome.
|Table 1. Total Soil NO3-N and OM by Grid, Felton, MN., 1996|
|Conventional field soil test = 62 lb/A, 0-4' nitrogen|
|Table 2. Available Total NO3-N lb/A (0-2') for 1996 Sugarbeet Crop by Grid, Foxhome, MN.|
|Conventional field soil test was 53 lb/A nitrogen, 0-2'|
Nitrogen recommendations by grid for Felton is shown in Table 3 and for Foxhome in Table 4. Wide variations in amounts of fertilizer nitrogen applied per grid occurred based on soil sampling method. Nitrogen applied based on organic matter adjustment ranged from 0 to 120 lbs/A. Nitrogen applied range from 14 to 108 lbs/A based on normal grid sampling while the conventional nitrogen application was 80 lbs/A. At Foxhome, nitrogen fertilization based on grid sampling varied from 58 to 106 lbs/A versus a 97 lb/A nitrogen rate based on conventional sampling. However, only 3 of 12 grids varied more than 15 lbs/A from the conventional fertilization rate. Percent of fields over or under fertilized based on soil sampling method are shown in Table 5.
|Table 3. Nitrogen Recommendation (lbs/A) by Grid, Felton, MN., 1996|
|Table 4. Nitrogen Recommendation (lbs/A) by Grid for Foxhome, MN., 1996|
|Table 5. Percent of Fields Over or Under Fertilized Based on Soil Sampling Method versus Conventional Soil Sampling and Fertilization.|
|GRID||GRID + OM|
|Table 6. Effect of Soil Sampling Method on Sugarbeet Yield & Quality, NDSU/U of MN., Felton, MN., 1996|
|Sugar||Yield||Rec Sugar||Gross Return|
1 & 2
1 & 2
1 & 2
|(Plant population 160 beets/100 ft. row)|
The effects of grid sampling and variable rate spreading on sugarbeet yield and quality compared to the conventional method for Felton from the University data is shown in Table 6. The soilection grid sampling increased gross return by $36.00 per acre over conventional soil sampling. The organic matter fertilization adjustment increased gross return per acre by $31.00. A baseline organic matter content of four percent was used for this field and soil type. Nitrogen fertilization was increased by 3.0 lb/A for each 0.1 percent decrease in organic matter below 4.0 percent. Conversely nitrogen fertilization was decreased 3 lb/A for each 0.1 percent increase in organic matter above the four percent baseline.
The cooperating grower at Felton harvested each of the six treatment grids as an individual grower contract. The grower harvest resulted in $54.00/A more gross return from variable rate fertilization adjusted by organic matter content, Table 7. Standard variable rate fertilization by Soilection increased gross return by only $13.00/A compared to conventional methods.
The effects of grid sampling (0-2' deep only) and variable rate nitrogen application at Foxhome, MN. is shown in Table 8. North Dakota State University and University of Minnesota researchers data showed a major reduction of nearly 1600 lbs/A recoverable sugar and $244.00 lower return per acre from grid sampling and variable rate fertilization. They also observed a consistent reduction in plant population of 30 plants/100' of row in the variable rate fertilized grids. Not knowing the residual nitrate-nitrogen content in the 2-4' depth soil profile may contribute to these large unexpected differences. In contract to the university findings the grower results determined an increase of 207 and 111 lbs. recoverable sugar per acre from the variable rate fertilized grids, Table 9. Increased value of the recoverable sugar per acre was $38.00/A and $16.00/A, respectively.
|Table 7. Sugarbeet Yield & Quality as Determined by Grower Harvest at Felton, MN., 1996.|
|Sugar||SLM||Yield||Rec. Sugar||Gross Return*|
|Org. Matter||18.60||1.33||20.9||7219||1086 (+54)|
|* Basis - 1996 American Crystal Sugar Co. estimated 1996 payment formula|
|Table 8. Effect of Variable Rate N Management on Sugarbeet Yield & Quality, North Dakota State Univ./ Univ. of Minnesota, Foxhome, MN., 1996.|
|Pl Pop||Sugar||Yield||Rec. Sugar||Gross Return*|
|*Basis - American Crystal Sugar Co. 1996 estimated payment formula|
|Table 9. Sugarbeet Yield & Quality as Determined by Grower Harvest at Felton, MN., 1996.|
|Sugar||Yield||Rec. Sugar||Gross Return*|
|* Basis - American Crystal Sugar Co. 1996 estimated payment formula|
I. Concerns with North Dakota State University/University of Minnesota and grower data at Foxhome, MN. include:
II. Conclusions/Foxhome, 1966
III. Conclusion/Felton, 1996
Tim Amble -
Randy Larson -
Centrol, Inc. -
Foxhome - Bernie/Kevin Etzler
Felton - Ray Johnson
Dan Bernhardson/Dave Braaten, American Crystal Sugar Co., Moorhead, MN
Bob Skelton, Minn-Dak, Wahpeton, ND
C. Hotvedt, American Crystal
Sugarbeet Research and Education Board of Minnesota and North Dakota
1996 Sugarbeet Research and Extension Reports. Volume 27, pages 92-97.