POSTER PRESENT A T/ONS CAN THE ILLINOIS N TEST IMPROVE NITROGEN MANAGEMENT IN SUGAR BEET? C.A.M. LABOSKI ( 1 ), J.A. LAMB (2), A.L.SIMS ( 3 ) 11! Department of Crop and Soil Sciences. Michigan State University 286 Plant & Soil Sciences Building, East Lansing, Ml 48824 USA 12! Department of Soil, Water, and Climate. University of Minnesota 1991 Upper Buford Circle, Saint Paul, MN 55108 USA 13! Northwest Outreach and Research Center, University of Minnesota 2900 University Ave. Crookston, MN 56716 USA ABSTRACT Managing soil nitrogen is essential to optimize sugar beet quality. Nitrogen fertilizer recommendations for sugar beet in the North Central States varies by growing region. Regional differences in methods of determining nitrogen fertilizer recommendations can be attributed to differences in climate, soil organic matter, soil texture. and payment formulas The Illinois soil N test (ISNT) measures a fraction of organic nitrogen (amino sugar-n, AS-N) that may mineralize during the growing season The ISNT has not been previously used in sugar beet production Nitrogen fertilizer rate studies were conducted in Michigan and Minnesota. The concentration of nitrate and AS-N in the soil was measured prior to planting AS-N was correlated to the response of recoverable white sugar per hectare () to N fertilization For the Michigan sites, there was a distinct separation in AS-N concentrations between responsive and nonresponsive sites. From this very preliminary data set, it appears that the ISNT may be useful in helping to predict sites where sugar beet will not benefit from additional fertilizer N, and perhaps may be used to fine tune N fertilizer recommendations for individual fields. More research is needed to better understand the performance of the ISNT under the environmental conditions of Michigan and Minnesota. INTRODUCTION Managing soil nitrogen (N) is essential to optimize sugar beet quality. Nitrogen fertilizer recommendations for sugar beet in the North Central States varies by growing region In Michigan the recommended rate is 5 kg N ha 1 for each Mg of expected yield In Minnesota and North Dakota, 112 kg N ha-0.6m- 1 or 146 kg N ha-1 2m- 1 soil nitrate-n plus fertilizer N is recommended. Regional differences in methods of determining nitrogen fertilizer recommendations can be attributed to differences in climate, soil organic matter, soil texture, and payment formulas. The Illinois soil N test (ISNT) is a new soil nitrogen test that measures the amino sugar fraction of organic nitrogen that may mineralize during the growing season (Mulvaney, R.L. eta/., 2001). Potentially the ISNT can account for differences in climate, organic matter, and texture. The ISNT has been able to predict sites where no additional fertilizer nitrogen was needed and has been correlated to 1st joint 1/RB-ASSBT Congress, 26th Feb.-1st March 2003, San Antonio (USA) 717
the optimum nitrogen rate for corn in Illinois; it has not been tested on other field crops. The objective, of this first year of research, is to determine whether or not the ISNT can improve nitrogen fertilizer recommendations by taking into consideration mineralizable organic nitrogen METHODS AND MATERIALS Five locations in Michigan and four in Minnesota were selected to assess sugar beet response to N fertilization. Site characteristics are provided in Table 1 Soil was sampled in the spring prior to planting at sites 1-7. Sites 8 and 9 were sampled in the fall prior to planting. Soil N03- -N was analyzed to a depth of 12 m, except at the Michigan sites (1-5) where soil was only sampled to 0.9 m (Table 2). Amino sugar-nitrogen (AS-N) was measured (Khan, SA eta!, 2001) on soil from the 0-0 15 m and 0-0 3 m depths (Table2) Organic matter was measured on the 0-0 15 m samples for the Michigan sites. At sites 1-5, urea fertilizer was knifed in at sidedress at the following rates 0, 34, 67, 101, 134, 168, 202, and 235 kg N ha 1 Urea was applied preplant and incorporated at sites 6-9. The N rates were as follows 0, 45, 90, 134, and 179 kg N ha 1 at site 6: 0, 56, 112, 168, and 224 kg N ha- 1 at site 7: and 0, 34, 67, 101, 134, and 168 kg N ha- 1 at sites 8 and 9 Treatments were replicated four times at sites 1-5, 8, and 9; and five times at sites 6 and 7 Sugar beet was planted in plots which varied in size from 4.56 x 15 2 m to 13.38 x 13.38 m. Row spacing was 0.76 m at sites 1-5 and 0 56 m at sites 6-9. Sugar beets were planted in April and May 2002 Roots were harvested in October and November 2002 /o/1/t' I. Si f1' cilomclcn~tic. ;, Site State Previous Crop Soil Type 1 Michigan Zea mays L. Misteguay 2 Michigan Phaseolis vulgaris Misteguay 3 Michigan Phaseolis vulgaris Parkhill loam 4 Michigan Glycine max L. Sloan 5 Michigan Zea mays L. Sloan 6 Minnesota Zea mays L. Crooksford silt loam 7 Minnesota Zea mays L. Seaforth loam 8 Minnesota Zea mays L. Wheatville loam 9 Minnesota Triticum vulgare Wheatville loam Soil Taxonomic name Fine, mixed, calcareous, mesic Aerie Enuoaquepts Fine, mixed, calcareous, mesic Aerie Endoaquepts Fine-loamy, mixed, semiactive, nonacid, mesic Mollie Endoaquepts Fine-loamy, mixed, superactive, mesic Fluvaquentic Endoaquolls Fine-loamy, mixed, superactive, mesic Fluvaquentic Endoaquolls Fine-silty,mixed, mesic, Calcic, Hapludolls Fine-loamy, mixed, mesic, Aquic, Calciudolls Silty over clayey, mixed over smetitic, superactive, Aerie Calciaquoll Silty over clayey, mixed over smetitic, superactive, Aerie Calciaquoll 718 1 51 joint 1/RB-ASSBT Congress. 26 1 h Feb.-1 51 March 2003, San Antonio (USA)
Recoverable white sugar per hectare () was calculated on a fresh beet basis for sites 1-7, by using the formula 1000 kg Mg- 1 * %sucrose * %clear juice purity * yield Mg ha- 1. Clear juice purity data was not available for sites 8 and 9. was calculated as 1000 kg Mg- 1 * (% sucrose - % loss to molasses) * yield Mg ha- 1. was regressed on rate of N fertilizer applied using a quadratic plateau model and nonlinear regression. The optimum N rate and were calculated from the quadratic plateau model as the join point and plateau, respectively. Data from sites 3 and 4 did not fit a quadratic plateau model. A linear model with zero slope best described these sites. Thus, the optimum was the intercept and the optimum N rate was 0 kg ha- 1. The response of ton fertilization was calculated as 100*((optimum check plot )/check plot )). Table 2 contains optimum N rate and, as well as, response ton fertilization. RESULTS AND DISCUSS! ON In order to determine relationships between response, optimum, optimum N rate and soil nitrogen concentrations, correlations between these parameters were calculated (Table 3) When all sites were considered, response was related (P < 0.1) to soil N03- -N at 0-0 6 m and soil AS-N at 0-0 15 m. However, when sites were separated by state, response in Michigan was better correlated ( P < 0 05) to N03 -N at 0-0.9 m and AS-N at 0-0 3 m: while response in Minnesota was unrelated to any soil N parameter Figure 1 shows the relationship between response to N fertilization and AS-N at 0-0 3 m and N03 -N at 0-1 2 m for all sites. Optimum N rate was correlated to AS-N at 0-0 3 m for both states (Table 3 and Figure 1 ). For the Michigan sites, soil organic matter was significantly (P < 0.01) correlated to AS-N at 0-0 3 m and the optimum N rate. It is currently being proposed for corn (Zea mays L ) production in Illinois, that yield will not be responsive to N fertilization on soils with AS-N concentrations, above 250 mg kg 1 in the 0-0 6 m of soil (Mulvaney, R.L et at, 2001 ). The data for sugar beet production in Michigan appear to line up with this threshold value. However, in Minnesota, there was a wide range in concentrations of AS-N that produced minimal response to N fertilization In conclusion, from this very preliminary data set, it appears that the ISNT may be useful in helping to predict sites where sugar beet will not benefit from additional fertilizer N, and perhaps may be used to fine tune N fertilizer recommendations for individual fields The strong correlation of AS-N with organic matter suggests that organic matter may be as useful when making field specific nitrogen recommendations. More research is needed to better understand the performance of the ISNT under the environmental conditions of Michigan and Minnesota. 1st joint 1/RB-ASSBT Congress, 26th Feb.-1st March 2003, San Antonio (USA) 719
Table 2. Response of R~VSA ton fertilizer, quadratic plateau model results, mzd soil N CO/ICC/I tra ti011 S. Site response 64 2 41 3 4 5 6 7 8 9 40 2 16 64 5 Optimum Optimum No3- -N No3- -N N rate 0-0.6 m 0-1.2 m -------------------- kg ha- -------------------- 9748 169 28.3 38.6 12963 9900 12748 9955 10072 9594 6506 6791 138 0 0 127 26 40 129 136 37.9 38.9 41.2 39.1 35.8 53.8 11.2 32.0 48.9 58.4 65.4 57.5 54.9 88.5 16.5 35.4 AS-N AS-N 0-0.15 m 0-0.3 m ----- mg kg- ----- 210 194 250 230 278 269 285 185 272 314 172 179 279 188 236 277 140 132 Organic Matter % 2.73 2.85 3.90 4.10 2.60 Table 3. Correlation of response to Nfertili:ation and optinu1111 N rate wit it inorganic and organic nitrogen in t!tc soil profilef(jr all sites and sites diz>idcd by state. Optimum N03- -N N rate 0-0.6 m All sites Response 0. 787** -0.593* N03 -N 0-0.6 m N03 -N 0-1.2 m Michigan sites Response 0.986*** -0.515-0.787 No3- -N 0-0.6 m N03 -N 0-1.2 m AS-N 0-0.3 m Minnesota sites Response 0.482-0.681-0.713 N03 -N 0-0.6 m No3- -N 0-1.2 m -0.695 AS-N AS-N 0-0.15 m 0-0.3 m -0.552-0.587* -0.508-0.635* -0.797** -0. 784** 0.962*** 0.754** 0.755** 0.829*** 0.838*** 0.955*** Organic Matter -0.932** -0.881 ** -0.808* -0.908** -0.830* -0.813* -0.912** -0.962*** 0.929** 0.471 0.595 0.530 0.507 0.664 0.698 0.978*** 0.903** 0.960*** -0.556-0.795 0.968** -0.475-0.935* 0.865 0.952** -0.405-0.943* 0.820 0.927* 0.996*** *, '-*. ***Significant at t!te 0.10, (J.OS, muf 0.01 probability levels, respectively. Figure 1. Relations/tip hetwcen R~VSA respmzse to Nfertilization and 11111i11o sugar-n (A) and nitratc-n (B) for all sites. 720 1st joint 1/RB-ASSBT Congress, 26th Feb.-1st March 2003, San Antonio (USA)
REFERENCES POSTER PRESENTATIONS 1. Khan, S.A., Mulvaney, R.L., & Hoeft, R.G. (2001). A Simple Soil Test For Detecting Sites that are Nonresponsive to Nitrogen Fertilization. Soil Sci. Soc. Am. J. 651751-1760. 2. Mulvaney, R.L., Khan, S.A., Hoeft, R.G., and Brown, H.M. (2001 ). A Soil Organic Nitrogen Fraction that Reduces the Need for Nitrogen Fertilization. Soil Soc. Sci. Am. J. 65:1164-1172. 1st joint 1/RB-ASSBT Congress, 26th Feb.-1st March 2003, San Antonio (USA) 721