Nitrogen Fertility Effects on Grain Yield, Protein, and Oil of Corn Hybrids with Enhanced Grain Quality Traits

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Peter R. Thomison, and Allen B. Geyer, Department of Horticulture and Crop Science, Ohio State University, 2021 Coffey Road, Columbus 43210; Bert L. Bishop, Computing and Statistical Services, Ohio Agricultural Research and Development Center, Wooster 44691; John R. Young, Dow AgroSciences L.L.C., Indianapolis, IN 46268-1054; and Edwin Lentz, Ohio State University Extension, Findlay 45840

Abstract

Grain of corn (Zea mays L.) hybrids containing nutritionally enhanced genetics may exhibit higher oil and crude protein profiles than normal field corn. However, the impact of N management on these traits is not well understood. Field experiments were conducted at Hoytville, OH from 2000 to 2002 to determine effects of different timings of nitrogen application (at planting versus split) and N rates (0, 60, 120, and 180 lb/acre) on the grain yield, protein, and oil of two corn hybrids containing Supercede genetics. Grain protein concentration showed more consistent response to increasing N rates than did yield. Protein exhibited a linear response to increasing N rates each year. Yield responded positively to increasing N rates in 2001 and 2002 but showed no additional response above 60 lb of N per acre in 2000. Split applications of N increased grain protein concentration in two of the three years, but had little or no effect on yield. Grain oil concentration was not influenced by the timing of N application and responded to N rate only in 2001. Results of the study demonstrate that N management will be an important factor in maximizing the grain protein of nutritionally enhanced hybrids, but producing grain with consistently high protein concentration may be difficult given the variation in growing conditions and environments characteristic of this part of the Corn Belt.

Introduction

In recent years, several new types of specialty corn have been developed with improved nutritional traits to better meet the needs of livestock producers (17). For example, grain from corn hybrids containing ‘Supercede’ genetics, licensed by Dow AgroSciences, has been reported to contain higher oil, crude protein, and amino acid profiles than normal yellow corn. Because of the greater concentration of nutrients on a dry weight basis, feeding nutritionally enhanced grain may be a viable method to improve feed efficiency and reduce expensive fat and protein inputs for livestock producers (8,13). This approach might allow livestock producers to manage the cost/benefit ratio of feed ingredients more economically. Contract production of Supercede corn might also provide growers with higher profits through premiums based on protein or oil concentration (17).

A major consideration in successful high-quality grain production will be the effective use of N fertilizer to ensure high yields and optimize grain protein. While the effects of N fertilization on the yield and grain composition of conventional corn hybrids have been investigated extensively, effects of N application on the performance of nutritionally enhanced corn hybrids, including those that contain Supercede genetics, have received little attention.

In the eastern Corn Belt, excessive rainfall after planting often results in N loss through denitrification and leaching (12,20). This problem is exacerbated when corn is produced on imperfectly drained soils that are common in parts of Ohio and neighboring states. Under such conditions, splitting the application of N, with some N applied at planting and the remainder sidedressed during early vegetative growth, may result in grain yields comparable to or higher than those obtained by applying all N at or before planting (3,12,14,21). However, little is known concerning the timing of N application on grain composition.

Many studies have shown that increasing N rates results in a higher crude protein concentration in conventional corn grain (11). Results from experiments evaluating timing of N on grain protein have been mixed, and most research has focused on fall versus spring applications. Jellum et al. (6) reported no difference with fall versus spring applications on grain N composition, whereas Warren et al. (18) found that N concentration was higher in grain produced with spring applied N than fall applied N, and that a nitrification inhibitor increased grain protein. In contrast to grain protein, research has generally indicated that N fertility level has little effect on grain oil concentration of conventional corn hybrids (11).

Unlike commodity grain production, profitability in nutritionally enhanced corn production is based not only on grain yield but also on the protein and oil concentration of the grain. Higher grain protein and oil concentrations command higher premiums, but if grain protein or oil concentrations fall below a specified level (about 6.0% for oil and 10.0% for crude protein on a dry matter basis) no premium is offered (17). A better understanding of the response of nutritionally enhanced corn to N fertilization across varying growing conditions is needed to help growers make more profitable management decisions for optimizing grain yield, protein, and oil. Growers may be able to produce grain with more consistent composition by adjusting their N management practices.

The major objective of this study was to measure the impact of varying N rates and timings of N application on the grain yield, and protein and oil composition of corn hybrids containing Supercede genetics. Results of this research could help define N management practices best suited for nutritionally-enhanced corn grain production on soils conducive to denitrification and N leaching during periods of prolonged saturation in the spring.

Field Experiments

Field experiments were conducted on a drained Hoytville silty clay loam (fine, illitic, mesic, Mollic Epiaqualf) at The Ohio State University (OSU) - Ohio Agricultural Research and Development Center (OARDC) Northwest Branch Research Farm (NWBRF) near Hoytville, OH, from 2000 through 2002. The planting dates were 6 May in 2000, 9 May in 2001, and 31 May 2002. The previous crop each year was wheat (Triticum aestivum L. em Thell.). Plots were planted using conventional tillage. Soil test results indicated that levels for pH, P, and K were within the optimal range for corn production. Insect and weed management strategies for minimizing crop stress were followed each year. Plant population at harvest averaged 30,800 to 32,500 plants per acre.

A randomized complete block design in a split-plot arrangement replicated four times was used in each experiment. Main plot treatments consisted of two Mycogen brand corn hybrids containing Supercede genetics: M2654 and M2655 in 2000, and M2654 and M2660 in 2001-2002. The relative maturity and growing degree day (GDD) ratings from VE to R6 (15) of the hybrids was approximately 107 days and 2665 GDDs, respectively. M2654 contains a modified Bacillus thuringensis (Bt) gene (event 176) for protection against European corn borer [Ostrinia nubilalis (Hubner)]. Subplot treatments consisted of a zero-N check and three N fertilizer rates applied either at planting or in a split application (seven N treatments). At planting, N at 40 lb/acre was applied as urea (2 inches to the side and 2 inches below the seed) to each N treatment plot. Urea-ammonium nitrate solution (UAN; 28%) was applied at three rates for total N applications of 60, 120, 180 lb/acre, either at planting or sidedressed at corn growth stage V4 -V5 (approximately 25 to 30 days after planting). The UAN treatments were applied with a solid stream injector behind a no-till coulter approximately 7 inches away from each row. Subplot size for an individual hybrid and N treatment was 10 feet wide (four 30-inch rows) and 80 feet long. In each experiment, a 60-foot border was planted with M2654 to separate the hybrids with Supercede genetics from any neighboring conventional corn. This border minimized foreign pollen contamination of the Supercede corn.

Final plant stand and numbers of stalk lodged (stalk breakage below the ear) were recorded at maturity prior to harvest. The center two rows of each four-row plot were harvested by combine and grain yields were adjusted to 15.5% moisture. Following physiological maturity but prior to harvest, 10 ears were selected from plants in the center two rows of each plot. These ears were shelled and grain samples from each plot were measured for oil and protein concentration using near infrared transmission (NIT) spectroscopy analysis (5). Analyses of oil and protein concentration are presented on a dry-weight basis.

Analyses of variance and correlation coefficients for the data were calculated using the mixed and correlation procedures of SAS (16). For the analyses of variance, the fitted models were 2 × 7 factorials arranged in randomized complete blocks. Contrasts were generated from the ANOVA results to test N rates, timing of application, linear and quadratic effects of N rate, and the interaction of the linear effect of N rates with timing of application. Since the zero-N treatment was independent of the timing treatments, the interaction of the linear effect of N with timing of application was tested using only those treatments where N was actually applied, either at planting or in a split application.

Grain Yield Response to Nitrogen

Grain yields, averaged across hybrids and N treatments, were 130, 127 and 81 bu/acre in 2000, 2001, and 2002, respectively. Yields in 2002 were reduced by late planting caused by excessive precipitation in May, and hotter and drier than normal conditions in June and July (Fig. 1). Yields were affected by hybrid in 2000 and 2001, and by N treatment each year, but no hybrid × N treatment interactions were present. Because some European corn borer injury was detected in plots each year, the Bt gene in M2654 may have contributed to a yield advantage over the non-Bt hybrids, M2655 and M2660, in 2000 (136 versus 128 bu/acre) and 2001 (131 versus 123 bu/acre), respectively.

Fig. 1. Growing season precipitation and mean air temperatures for Hoytville, OH, 2000-2002.

The response to N rate was similar for both timing of application methods as indicated by the absence of a rate linear × timing interaction. Much of the N treatment effect on yield could be attributed to significant differences between the zero-N check and all other N treatments each year (Fig. 2). Yield was not affected by timing of N application. This result is consistent with previous research at this location involving the same soil type, which indicated no differences in yield response to timing of N application (3). Significant linear responses to N application rate occurred each year and quadratic responses to N rate were significant in 2000 and 2001. The N rates required to optimize yield varied each year (Fig. 2). In 2000, yield showed no response to increasing N rates above the application of N at 60 lb/acre. Although growing conditions (Fig. 1) and site yield levels were considerably different in 2001 and 2002, yield response to increasing N rates was similar with yields increasing through the 180-lb/acre rate both years (Fig. 2).

Fig. 2. Effect of nitrogen rate and timing on corn grain yield, averaged across hybrids, Hoytville, OH, 2000-2002. Vertical bars represent ± standard error of the mean.

Nitrogen treatment significantly affected lodging in 2000. This was primarily due to a difference between the zero-N check (28% lodged) and the rest of the N treatments (18% lodged). Hybrid effects and hybrid × N treatment interactions in 2000 were not significant (data not shown). Lodging was negligible in 2001 and 2002, and averaged less than 7% (data not shown).

Grain Protein Concentration

Grain protein concentration, averaged across hybrids and N treatments, were 9.2, 7.5, and 9.4% in 2000, 2001, and 2002, respectively. The relatively low percent grain protein in 2001 (Fig. 3) may be attributed to protracted wet soil conditions during the spring (Fig. 1), which favored loss of N through denitrification and leaching. Drier and warmer than normal conditions during late vegetative development and grain fill (Fig. 1) may have contributed to the higher grain protein composition in 2002 (Fig. 3). In conventional hybrids, drought stress during grain fill generally increases grain protein (4) whereas optimum soil moisture, whether from rain or irrigation, reduces protein concentration (11).

Fig. 3. Effect of nitrogen rate and timing on corn grain protein concentration, Hoytville, OH, 2000-2002. Vertical bars represent ± standard error of the mean.

Hybrid and N treatment affected grain protein each year, but no hybrid × N treatment interaction was present. Effects of timing of N application on grain protein were significant in 2000 and 2001 with higher protein concentration associated with the split-N application (Fig. 3). Grain protein was not affected by timing of N application in 2002. Jung et al. (7) evaluated the effects of N applied on conventional hybrids at six times (from 5 to 12 weeks) after planting and found that yields declined with N applied after the 8th week, but that grain N concentration increased with later N applications. In this study, sidedress N applications were made within 4 to 4 weeks of planting, which may have limited potential effects of N on grain protein. Grain protein increased in response to increasing N rates through the 180 lb/acre rate each year (Fig. 3), which is similar to previous studies (11). Quadratic responses were evident in 2000 and 2002. Grain protein showed a more consistent response to increasing N rate than grain yield (Fig. 3). In 2000, grain protein was more responsive to increasing N rate than grain yield, which showed no response to N above the rate of 60 lb/acre (Fig. 2 and 3). Nitrogen rates required to maximize grain protein are often greater than the N required to optimize yields (11).

Grain Oil Concentration

Averaged across hybrid and N treatment, grain oil concentration were 6.0, 6.5 and 6.4% in 2000, 2001, and 2002, respectively. Hybrid × N treatment interactions were not significant. However, in 2001, the grain oil concentration of the two hybrids exhibited different responses to N rate as indicated by a significant linear N rate × hybrid interaction. The grain oil concentration of the zero-N check of hybrid 2654 was higher than that of the same hybrid with the N treatments, but for 2660 there was no difference in oil concentration between the zero-N check and the N treatments (data not shown). Oil concentration was affected by hybrid in 2001 and 2002, with hybrid 2654 slightly higher than that of 2660 (6.7% vesus 6.3% in 2001; 6.5% versus 6.3% in 2002). Grain oil concentration was affected by N treatment only in 2001 with most of this effect attributable to significant differences in oil concentration between the zero-N check and all other N rates (Fig. 4). Grain oil concentration was not influenced by the timing of N application (Fig. 4). A recent Illinois study of high oil TC Blends (Nafziger, 1998, unpublished) concluded that grain oil concentration was not influenced by N rates. In conventional corn, Welch (19) reported that N applications increased grain oil slightly, but most research has shown that increasing N rates have little or no effect on grain oil concentration (11).

Fig. 4. Effect of nitrogen rate and timing on corn grain oil concentration, Hoytville, OH, 2000-2002. Vertical bars represent ± standard error of the mean.

Correlations

Grain protein was positively correlated with yield in 2000 (r = 0.22; P < 0.04), 2001 (r = 0.81; P < 0.0001), and 2002 (r = 0.47; P < 0.0003). Some studies have observed a negative relationship between yield and protein concentration when soil moisture is limiting (4). Despite high temperatures and dry conditions, a positive correlation existed between yield and protein concentration in the 2002 experiment, which could be attributed to positive responses of both yield and protein to increasing N rates. Cromwell et al. (2) and Kniep and Mason (9) found that grain yield and protein concentration were negatively correlated in high lysine corn hybrids, but no such association was observed in conventional hybrids.

Grain oil concentration was not significantly correlated with protein concentration or yield in 2000 or 2002 (data not shown). However in 2001, there were small negative correlations between oil concentration and yield (r = -0.43; P < 0.002) and oil and protein (r = -0.35; P < 0.009 ) which may be accounted for by the higher oil concentration of grain from the zero-N checks compared with that of the N treatments. Negative correlations between grain yield and oil concentration have been observed in high oil hybrids (10). However, in an evaluation of conventional corn hybrids grown with and without irrigation, Bullock et al. (1) found no evidence that oil concentration was significantly correlated to protein or grain yield.

Conclusions

The impact of timing of N application on grain protein was relatively small compared to effects of N rate and year-to-year variability in growing conditions. For all N treatments, including the zero-N check, oil consistently exceeded the grain specification of 6.0%; however grain protein was usually below 10.0% (except for the split-N treatment of 180 lb/acre in 2000). Results of the study demonstrate that N management will be an important factor in maximizing the protein of high oil hybrids but that it may be difficult to produce grain with consistently high protein given the variation in growing conditions and environments characteristic of this part of the Corn Belt.

Acknowledgments

We thank Dow AgroSciences for financial support and numerous grain quality analyses. An Ohio State University and Ohio Agricultural Research and Development Center Industry Small Grant also funded this investigation. Salaries and research support provided in part by State and Federal funds appropriated to the Ohio Agricultural Research and Development Center, The Ohio State University.

Literature Cited

1. Bullock, D. G., Raymer, P. L., and Savage, S. 1989. Variation of protein and fat concentration among commercial corn hybrids grown in the southeastern USA. J. Prod. Agric. 2:157-161.

2. Cromwell, G. L., Bitzer, M. J., Stahly, T. S., and Johnson,T. H. 1983. Effects of soil nitrogen fertility on the protein and lysine content and nutritional value of normal and opaque-2 corn. J. Anim. Sci. 57:1345-1351.

3. Eckert, D. J., and Martin, V. L. 1994. Yield and nitrogen requirement of no-tillage corn as influenced by cultural practices. Agron. J. 86: 1119-1123.

4. Genter, C. F., Eheart, J. F., and Linkous, W. N. 1956. Effects of location, hybrid, fertilizer, and rate of planting on the oil and protein content of corn grain. Agron. J. 48:63-67.

5. Itnyre, R. 1992. Evaluation of single kernel pedigree selection for developing improved high oil corn inbreds. M.S. thesis. University of Illinois, Urbana.

6. Jellum, M. D., Boswell, F. C., and Young, C. T. 1973. Nitrogen and boron effects on protein and oil of corn grain. Agron. J. 65:330-331.

7. Jung, P. E., Peterson, L. A., and Schrader, L. E. 1972. Response of irrigated corn to time, rate and source of applied N on sandy soils. Agron. J.64:668-670.

8. Kim, S. H., Park, S. Y., Choi, C. H., Kim, S. J., and Ryu, K. S. 2002. Feeding evaluation of Supercede corn on the performance, nutrients digestibility, and fatty acid composition of broiler chicks. Page 77 in: Poultry Sci. Assoc. 91st Annual Meeting Abstracts. August 11-14, 2002, Newark, Delaware.

9. Kniep, K. R., and Mason, S. C. 1991. Lysine and protein content of normal and opaque-2 maize grain as influenced by irrigation and nitrogen. Crop Sci. 31:177-181.

10. Lambert, R. J. 2001. High-oil hybrids. Pages 131-154 in: Specialty Corns. A. R. Hallauer, ed. CRC Press, Boca Raton, FL.

11. Mason, S. C., and D’Croz-Mason, N. E. 2002. Agronomic practices influence maize grain quality. J. Crop Prod. 5:75-91.

12. Miller, F. H., Kavanaugh, J., and Thomas, G. W. 1975. Time of N application and yields of corn in wet, alluvial soils. Agron. J. 67:401-404.

13. Owens, F., Soderlund, S., and Hind, M. 2001. Developing new specialty grains for ruminants. Pages 48-69 in: Proc. 13th Annual Florida Ruminant Nutrition Symposium, 11 Jan. 2002, Gainesville, FL.

14. Randall, G. W. 1984. Efficiency of fertilizer nitrogen use as related to application methods. Pages 521-533 in: Nitrogen in Crop Production. R. D.Hauck, ed. ASA, CSSA, and SSSA, Madison, WI.

15. Ritchie, S. W., Hanway, J. J., and Benson, G. O. 1992. How a corn plant develops. Spec. Rep. 48. Iowa State Univ. Coop. Ext.

16. SAS Institute. 1995. SAS user’s guide: Statistics. 6th ed. SAS Inst., Cary, NC.

17. U.S. Grains Council. 2002. 2001-2002 value-enhanced grain quality report. U.S. Grains Council, Washington, D.C.

18. Warren, H. L., Huber, D. M., Tsai, C. Y., and Nelson, D. W. 1980. Effect of nitrapyrin and N fertilizer on yield and mineral composition of corn. Agron. J. 72:729-732.

19. Welch, L. F. 1969. Effect of N, P, and K on the percent and yield of oil in corn. Agron. J. 61:890-891.

20. Welch, L. F. 1984. Nitrogen management for the East North Central States. Pages 707-719 in: Nitrogen in Crop Production. R. D. Hauck, ed. ASA, CSSA, and SSSA, Madison, WI.

21. Welch, L. F., Mulvaney, D. L., Oldham, M. G., Boone, L. V., and Pendleton, J. W. 1971. Corn yields with fall, spring, and sidedress nitrogen. Agron. J. 63:119-123.