Illinois
Fertilizer Conference Proceedings
January 24-26, 2000
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R.J. Lambert, R.W. Esgar, and D.K. Joos1
Management of fertilizer nitrogen (N) in Illinois is of economic and environmental concern to corn producers and the urban population. The response of corn hybrids to fertilizer-N is affected by time of application, rates, plant densities, soil type, previous fertilizer-N applications, and hybrid (Russell, 1986; Jokela and Randall, 1989; Schepers and Below, 1987; Krone and Lambert, 1995). The N-rate maximizing grain yields can vary from 70 to 136 lbs of N acre-1 depending on hybrid and past management practices (Vanotti and Bundy, 1994). Corn hybrids vary in their requirements for fertilizer-N, but the soil and environment play an equally important role (Gardner et al. 1990).
Data reported in 1998 at this conference (Lambert et al. 1998) using six fertilizer-N rates (0, 40, 80, 120, 160, 200, 240) and four locations in Champaign County and one hybrid showed that as N-rates increased, grain protein content increased from 7.9%o at 0-N to 10% at 240 lbs of N with grain yields increasing from 98 to 181 bushels/acre in a curvilinear fashion. Nitrogen removal in the grain increased from 70 lbs of N/acre at 0-N to 173 lbs of N/acre at 240 lbs of N. At the 160 lbs N-rate, the N-removal was equal to the applied N. Yields above the 160 lbs N rate removed less N than applied, and yields below this rate removed more N than applied.
There is a need to develop a rapid, inexpensive method for estimating N-use of corn hybrids for on-farm use. Several near-infrared reflectance or transmittance instruments are available that could be used for this purpose. They estimate the total amount of protein in whole kernels that can be converted to percent nitrogen. This value could then be used to estimate N removal from the soil. Once information is available on factors that cause variation in the estimates of this procedure, the method could be adapted for on-farm use.
The objective of this study was to determine the environmental effects and hybrid (genotype) on nitrogen removal in the grain of commercial corn hybrids grown at three locations in Illinois in 1999.
The varietal testing program of the Department of Crop Sciences of the University of Illinois offers a unique opportunity to grow a large number of commercial corn hybrids at a location and under varying environmental conditions. The three locations used in this study were Brownstown, Dwight, and Urbana, IL,. The environmental characteristics of the three locations are presented in Table 1. Nitrogen was fall applied as anhydrous ammonia at Dwight and spring applied as ammonium nitrate at Brownstown and 28% UAN at Urbana.
All plots were machine planted and harvested. Herbicides were used at the three locations for weed control. All plots were over planted and thinned to a perfect stand (Table 1). Plot sizes varied in length, but each plot was four 30-inch rows wide. The center two rows were harvested for grain yield. A sample of shelled grain was saved from each plot at each location for protein analysis. All grain samples were dried to a moisture content ranging from 8.9 to 10%. Total protein concentration was estimated using Near-infrared transmittance (NIT) which also gave the concentration of oil and extractable starch in a sample (Itynre, 1992). The protein values were converted to percent-N by dividing by 0.0625. Grain yields were determined for each plot as No. 2 yellow corn. The pounds acre-1 of corn was multiplied by the percent-N for each plot to obtain an estimate of the nitrogen removed in the grain. The nitrogen removed by a hybrid was estimated by averaging the values from the three replications.
Because of the large number of hybrids tested at each location, each replicate was large, so to control variation within a replicate, a designs were used at each location. This type of design adjusts for the environmental variation within a replicate. Each trial was replicated three times. Analysis of variance procedures were used to analyze the data at each location. The Dwight and Urbana locations had the same 190 hybrids, and 43 of the 126 hybrids at Brownstown were also grown at Dwight and Urbana.
An increase in yield and/or protein increases N removal from soil (Figure 1). At a yield of 180 bu/acre, N removal in grain will increase from 129 lb N/acre at 8% protein to 161 and 194 lb N/acre at protein concentrations of 10 and 12%, respectively.
Data in Table 2 shows the average yields, protein concentration, percent N, pounds of N/acre, percent oil, and percent starch for the three locations, with Brownstown having the lowest yield and highest grain protein (10.8%) but having removed the lowest amount of N in the grain (115). The Urbana location had the highest yields (211) and the lowest grain protein (9.6%) and removed 181 pounds of N/acre in the grain, which was about equal to the fertilizer N applied (180). Table 3 gives the range in values for yield, percent protein, pounds N/acre, and percent oil and starch plus the coefficient of variation (CV). When a large number of commercial corn hybrids (126 to 190) are evaluated, one expects to find considerable variation as a result due to a number of environmental variables. However, the CVs for N removed were about equal for the three locations, with the range for Urbana being the largest (74) and Dwight the smallest (57).
The large number of hybrids tested makes it somewhat difficult to evaluate individual hybrid response. However, Table 4 compares the four highest-yielding commercial corn hybrids at the three locations. For the Brownstown and Dwight locations, the four highest-yielding hybrids removed less nitrogen in the grain than was applied as fertilizer-N (150 pounds at Brownstown and 180 pounds at Dwight). The Urbana location had a negative N balance or removed more N in the grain than was applied as fertilizer-N (180 pounds). Within a location, there is variation in the amount of N an individual hybrid removes. At Brownstown, two hybrids had the same yields (139), but one removed only 112 pounds of N/acre and the other 124 pounds of N/acre. Additional examples can be observed at Dwight and Urbana (Table 4).
Another comparison is the performance of a hybrid at the three locations. Table 5 gives the yields and N removal for 10 commercial hybrids that were grown at all three locations. The data in Table 5 shows that yields of a hybrid at the three locations varies considerably. Also, there are considerable differences in the amount of N removal at the different locations. Hybrid 5 removed 115 pounds N/acre at Brownstown, 134 pounds at Dwight, and 180 pounds at Urbana. Differences in N-removal within a location also were observed, with the largest difference at Brownstown being 29 pounds/acre, at Dwight 42 pounds/acre, and at Urbana 49 pounds/acre.
Based on a single year's results, using grain protein concentration to estimate N-removal by commercial corn hybrids appears to be a viable procedure. Data obtained in 1999 from three locations of the Illinois Corn Performance tests showed that location had the largest effect on N-removal in the grain, and hybrid also had an effect, with some hybrids removing less N than others at the same yield levels. Plans are to obtain an additional year's data and to analyze the data in greater detail.
Table 5. Grain yields and nitrogen removal in the grain for 10 hybrids grown at the three locations.
Figure 1. Effect of grain protein and yield on nitrogen removal by corn hybrids.
1 R.J. Lambert is Professor, R.W. Esgar is Agronomist, and D.K. Joos is Research Specialist in Agriculture, Dept. of Crop Sciences, Univ. Of Illinois, Urbana, IL.
Gardner, C.A., P.L. Bax, D.J. Bailey, A.J. Cavaleri, C.R. Clausen, G.A. Luce, J.M. Meece, P.A. Murphy, T.E. Piper, R.L. Segebart, O.S. Smith, C.W. Tiffany, M.W. Trimble, B.N. Wilson. 1990. Response of corn hybrids to nitrogen fertilizer. Journal of Production Agriculture, 3:39-43.
Itynre, R.L. 1992. Evaluation of single kernel pedigree selection for developing improved high oil corn inbreds. M.S. Thesis, Dept. of Agronomy, University of Illinois.
Jokela, W.E. and G.W. Randall. 1989. Corn yield and residual soil nitrate as affected by time and rated of nitrogen application. Agron. J. 81:720-726.
Krone, T.L., and R.J. Lambert. 1995. Maize genotypes developed at three soil nitrogen levels B. Hybrid evaluation. Maydica 40:217-222.
Lambert, R.1., R.G. Hoeft, L.C. Gonzini, and LL Warren. 1998. Monitoring nitrogen use of corn hybrids using grain protein concentration. In: 1998 Illinois Fertilizer Conference Proceedings (R.G. Hoeft, ed.) pp 97-104.
Russell, W.A. 1986. Contribution of breeding to maize improvement in the United States, 1920's-1980's. Iowa State J. of Res. 61:5-34.
Schepers, LIZ., and F.E. Below. 1987. Influence of corn hybrids on nitrogen uptake and utilization efficiency. Proc. 42nd Annual Corn and Sorghum Res. Cent. Amer. Seed Trade Assoc. Washington D.C. 42:172-186.
Schepers, J.R., K.D. Frank, and C. Bourg. 1986. Effect of yield goal and residual soil nitrogen concentration on fertilizer recommendation for irrigated maize in Nebraska. J. Fert. Issues 3:133-139.
Vanotti, M.B., and G. Bundy. 1994. Corn nitrogen recommendations based on yield response data. Prod. Agric. 7:249-256.
