Influence of Late-Season Foliar Nitrogen Applications on Yield and Grain Nitrogen in Winter Wheat

Transcription

1 Influence of Late-Season Foliar Nitrogen Applications on Yield and Nitrogen in Winter Wheat Curt W. Woolfolk, William R. Raun,* Gordon V. Johnson, Wade E. Thomason, Robert W. Mullen, Kathie J. Wynn, and Kyle W. Freeman ABSTRACT Wheat producers in the Great Plains typically use two Increasing grain protein in new higher-yielding cereal grains has options for applying N fertilizer: (i) all N fall-applied recently received added attention due to protein premiums paid to before planting or (ii) a small amount of N fall-applied, farmers. Hard red winter wheat (Triticum aestivum L.) studies were followed by a late-winter or early spring topdressing conducted at two locations in Oklahoma in , , (Kelley, 1995). Cooper (1974) demonstrated that dryand to evaluate the effects of late-season foliar N applica- land wheat receiving N at planting or before head emertions on grain yield, total grain N, straw yield, and total straw N. gence may respond with increases in grain yield but Foliar applications of N were made at two different times (pre- and may show little or no effect in grain protein content. postflowering) using urea ammonium nitrate (UAN) at rates of 0, 11, 22, 34, and 45 kg N ha Although preplant fertilizer applications decrease the 1. Ammonium sulfate [(NH 4 ) 2 SO 4 ] was also applied at a single rate of 22 kg N ha 1 both pre- and postflowering. potential for nutrient deficiencies in early stages of A significant linear increase in total grain N was observed for postflowering applications using UAN in five of six site-years. In four out mineral N from the previous season) may pose a risk growth, presence of residual soil NO 3 N (plant-available of the six site-years, a significant linear increase was observed for to the environment. Many researchers have found that preflowering applications of UAN. No consistent increases or de- preplant applications may lead to losses or immobilizacreases from foliar N applications were observed for grain yield, straw tion before plant uptake, thus greatly affecting N use yield, or straw N. Over years and locations, UAN applied preflowering efficiency (NUE) (Welch et al., 1966; Olson and Swaland postflowering at 34 kg N ha 1 increased total grain N over that of the check (no foliar N applied) by 2.7 and 2.4 g kg low, 1984; Lutcher and Mahler, 1988; Fowler and Bry- 1, respectively. Late-season foliar N applications before or immediately following don, 1989; Wuest and Cassman, 1992). The common pracflowering may significantly enhance grain N content and, thus, percent tice of using surface soil testing for adjusting fertilizer protein in winter wheat. N before planting is not suited for detecting late-season deficiencies. Mascagni and Sabbe (1991) and Boman et al. (1995) found that split applications are extremely protein is an important factor in determining important to maximize crop utilization of applied fertilmilling and baking quality of wheat. Market adplied N provides increased management flexibility by izer N throughout the growing season. Late-season ap- justments for wheat have been established worldwide based on protein content, with premiums commonly allowing farmers to adjust N rates according to crop paid for increases above baseline levels. In irrigated growth. Late-season N applications may also reduce hard red winter wheat, grain protein contents frequently potential N losses from leaching or denitrification over are 11.4% and often do not attract protein premiums the winter. Plant availability of N late in the season, (Strong, 1982). The desired protein of wheat depends on when soil moisture content is low and root uptake is the type and/or use of the wheat. High protein content is slowed, is particularly necessary for increasing grain pro- desirable in varieties of hard red winter wheat. Bread tein content and, many times, yield (Ellen and Spiertz, flour, certain foods (i.e., macaroni and egg noodles), 1980). Increasing grain protein by applying higher fertilizer and animal feeds require a high protein content (12 N rates is relatively inefficient (NUE decreases with 16%) while low protein content (8 11%) is preferred increasing N level), especially under dry soil conditions in many varieties of soft red winter wheat (Hunter and (Gauer et al., 1992). In-season N applied with point Stanford, 1973). Early research concluded that climate injection or topdressing can maintain or increase NUE was an influential factor for grain protein, but as soil N compared with preplant N in wheat (Sowers et al., 1994). became more limiting, it became apparent that grain Spiertz (1983) found that with a regular N supply, wheat protein levels in the High Plains region of the USA would usually attain 65 to 80% of its grain N from the were affected by N deficiencies (Daigger et al., 1976). vegetative parts, with the remainder originating from Nitrogen, which is a primary constituent of proteins, root uptake after flowering. Bhatia and Rabson (1976) is extremely susceptible to loss when considering that found that cereals with a typical protein concentration average recovery rates fall in the range of 20 to 50% would require an additional 6 to 11% fertilizer N for a for grain production systems in winter wheat (Raun 1% increase in grain protein, depending on the crop and Johnson, 1999). Cassman et al. (1992) noted the variety and the initial N concentration within the plant. importance of both preplant and in-season N fertilizer Wuest and Cassman (1992) found that while the availmanagement for optimizing both yield and protein in ability of soil N and water may often constrain postflowwheat. ering N uptake, applications of N near flowering increased postflowering N uptake, grain protein content, Dep. of Plant and Soil Sci., Oklahoma State Univ., Stillwater, OK and grain protein concentrations. Work by Dhugga and Contrib. from the Oklahoma Agric. Exp. Stn. Received 22 May *Corresponding author (wrr@mail.pss.okstate.edu). Abbreviations: AS, ammonium sulfate; NUE, nitrogen use efficiency; Published in Agron. J. 94: (2002). UAN, urea ammonium nitrate. 429

2 430 AGRONOMY JOURNAL, VOL. 94, MAY JUNE 2002 Table 1. Initial surface (0 15 cm) soil test characteristics and soil classification at Perkins and Stillwater, OK, Location ph NH 4 N NO 3 N P K Total N Organic C mg kg 1 gkg 1 Perkins Stillwater :1 soil/water. 2 M KCl extraction. Mehlich 3. Dry combustion. Waines (1989) showed that the N uptake capacity of year after year. A randomized complete block experimental grain is a determining factor for postflowering N uptake. design was used at both locations with four replications. At Applications of N near flowering increased postflowdata from samples collected before treatment application are both sites, plot size was 3.05 by 2.44 m. Results of soil test ering N uptake, grain protein content, and grain protein reported in Table 1. Nitrogen and P fertilizers were applied concentration (Bänziger et al., 1994; Bulman and Smith, and incorporated before planting under a conventional tillage 1993). system (two to three disk incorporations of wheat straw resi- Yield increases from foliar applications vary greatly. dues following harvest) at both locations. Nitrogen was broad- Finney et al. (1957) found that N applied preplant will cast preplant as ammonium nitrate (34 0 0) at a rate of 67 normally give a response equal to that of N applied up kg N ha 1 in the first year and 45 kg N ha 1 in the second to tillering in wheat. Nitrogen applied after tillering and and third year. These rates were based on soil test N and up to heading will normally give progressively smaller moderate to high yield goals. Phosphorus, as triple super phosyield increases. These authors also found that N applied phate (0 46 0), was applied with the N in 1997 at both loca- tions at a rate of 45 kg P ha 1, and an additional 45 kg P ha after heading usually did not result in yield increases in 1 was applied in Hard red winter wheat ( Tonkawa ) was most years unless N deficiency was severe. Similar work planted in 19-cm rows at a seeding rate of 78.5 kg ha 1 at by Below et al. (1985) reported no increases in corn both sites in mid-october of all 3 yr. (Zea mays L.) grain yield when foliar N was applied 7 d Foliar applications of N were applied at preflowering before and 7 d after anthesis at a total N rate of 22.3 (Feekes 10.5) and postflowering (Feekes ) stages of kgnha 1. Finney et al. (1957) indicated that the greatest growth (Large, 1954). The treatment structure employed at grain protein increases occurred when foliar N applicafor both sites is reported in Table 2. Dates of foliar N application each experiment were determined by collecting 20 random tions were applied at anthesis (flowering) and that rewheat heads from each experimental area and examining them sponses declined rapidly before or after that time. In under a 10 hand lens to assess maturity. Two N sources some cases, they noted that N applied during the fruiting commonly available in the central Great Plains were evaluated period could increase wheat protein from 10.8 to 21.0%. in the study. Liquid UAN (28 0 0) was foliar-applied with Foliar N applications are often associated with leaf no dilution at rates of 0, 11, 22, 34, and 45 kg N ha 1 (32.3, burn when applications are made early morning and 63.3, 94.2, and L ha 1, respectively). These rates corredew is still on the crop. Gooding and Davies (1992) sponded to volumes of 24, 47, 70, and 93 ml applied to each found higher levels of leaf burn with ammonium nitrate 7.43-m 2 plot. For the AS solution, 700 g of material (21% N) (NH 4 NO 3 ) and ammonium sulfate (AS) compared with was dissolved in 1000 ml of water, resulting in a total volume urea [(NH of 1300 ml. The AS solution was 8.6% N by weight and 11.4% 2 ) 2 CO]. It should be noted that their work and that of several others reported here has not included N on a weight/volume basis; therefore, this solution required a higher volume (114 ml) than UAN to achieve the single urea ammonium nitrate (UAN), which is now a common rate of 22.4 kg N ha 1. Both N sources were applied using foliar N source. 175 ml of mechanically pressurized spray bottles (No. 413, Fertilizer applications containing S may lead to in- Marianna Research Labs, Omaha, NE) to simulate an aerial creased grain quality due to beneficial N/S ratios within application. Because of the small plot size and application the plant. Gooding and Davies (1992) indicated that improvements method, spray patterns were simulated on paper to ensure in bread-making quality might be achieved if S nutrition was improved to maintain this ratio in the Table 2. Treatment structure employed that included N source, grain. Sulfur is an important constituent of wheat flour N rate, and time of application, Perkins and Stillwater, OK ( , , and ). gluten, and if S supply to wheat plants is inadequate, bread-making quality of the flour is reduced (Griffiths Treatment N source N rate Time of application and Kettlewell, 1990). kg ha 1 The objective of this experiment was to determine 1 0 Check the effects of late-season applications of varying rates 2 UAN 11 Preflowering 3 UAN 22 Preflowering of two N fertilizer sources (UAN vs. AS) at two times 4 UAN 34 Preflowering of application (pre- vs. postflowering) on grain yield, 5 UAN 45 Preflowering total grain N, straw yield, and total straw N. 6 AS 22 Preflowering 7 UAN 11 Postflowering 8 UAN 22 Postflowering MATERIALS AND METHODS 9 UAN 34 Postflowering 10 UAN 45 Postflowering In October 1997, two studies were initiated at Perkins, OK, 11 AS 22 Postflowering on a Teller sandy loam (fine-mixed, thermic, Udic Argiustoll) and at Stillwater, OK, on a Easpur loam (fine-loamy, mixed, Preflowering: foliar N applied just before flowering (late April, Feekes thermic, Fluventic Haplustoll). Studies were repeated for 3 yr 10.5); and postflowering: foliar N applied immediately following flowering (early May, Feekes ( , , and ) on the same plots, ).

3 WOOLFOLK ET AL.: INFLUENCE OF LATE-SEASON FOLIAR N APPLICATIONS ON WINTER WHEAT 431 Table 3. Treatment means for grain yield, grain N uptake, grain N, straw yield, straw N uptake, and straw N, Perkins, OK, Source Timing N rate Yield N uptake N Yield N uptake N Check Check UAN Pre UAN Pre UAN Pre UAN Pre AS Pre UAN Post UAN Post UAN Post UAN Post AS Post SED CV, % UAN pre lin NS NS ** NS NS NS UAN pre quad NS NS * NS NS NS UAN post lin NS NS ** NS NS * AS pre vs. UAN pre NS NS * NS ** ** AS post vs. UAN post NS NS ** NS * NS UAN pre vs. UAN post NS NS NS * * NS AS pre vs. AS post NS NS ** NS * NS AS pre vs. check NS NS ** NS ** ** AS post vs. check NS NS ** NS NS * uniform coverage. Sufficient leaf surface, good plant density, effects on grain yield, grain N uptake, grain total N (protein), and small spray volumes allowed for interception of UAN straw yield, and straw N uptake were evaluated using single and AS spray with minimal, if any, runoff from the foliage. degree-of-freedom, nonorthogonal contrasts (SAS, 1988). Treated plots were visually monitored for variation in leaf burn following the applications. At maturity, wheat was harvested using a Massey Ferguson RESULTS AND DISCUSSION 8XP combine from a 2.0- by 3.05-m area in each plot. Means and single degree-of-freedom contrasts for samples from the entire plot were also collected from the grain yield, grain N uptake, grain N, straw yield, straw harvested area in each plot. and straw samples were N uptake, and straw N are reported in Tables 3 through dried and ground to pass a 100- m sieve and analyzed for 8 for Perkins and Stillwater (1998, 1999, and 2000). Amtotal N content utilizing a Carlo-Erba NA 1500 Series II dry monia volatilization losses from UAN were not excombustion analyzer (Schepers et al., 1989). N uptake and straw N uptake were calculated by multiplying yield by pected to be significant because N was applied during total N concentration within the respective plant part. Wheat early morning hours when temperatures were cool and grain protein can be determined by the following: total grain wind velocity was low. N(gkg 1 )/ (Martin del Molino, 1991). Treatment Limited ( 10% surface damage) foliar burn was ob- Table 4. Treatment means for grain yield, grain N uptake, grain N, straw yield, straw N uptake, and straw N, Perkins, OK, Source Timing N rate Yield N uptake N Yield N uptake N Check Check UAN Pre UAN Pre UAN Pre UAN Pre AS Pre UAN Post UAN Post UAN Post UAN Post AS Post SED CV, % UAN pre lin NS NS ** NS NS * UAN post lin NS NS ** NS NS NS

4 432 AGRONOMY JOURNAL, VOL. 94, MAY JUNE 2002 Table 5. Treatment means for grain yield, grain N uptake, grain N, straw yield, straw N uptake, and straw N, Perkins, OK, Source Timing N rate Yield N uptake N Yield N uptake N Check Check UAN Pre UAN Pre UAN Pre UAN Pre AS Pre UAN Post UAN Post UAN Post UAN Post AS Post SED CV, % UAN pre lin NS NS ** NS NS * UAN post lin NS NS ** NS NS NS UAN post quad 0.13 NS NS NS NS NS AS pre vs. check NS NS ** NS NS NS served at either site in all years. However, a tendency was applied postflowering at the 22 kg N ha 1 rate (Ta- for increased foliar burn was observed with AS comand/or ble 5). At Stillwater in 1999, UAN applied preflowering pared with UAN applications. Foliar burn from AS at postflowering tended to decrease yields at the a rate of 22 kg N ha 1 was similar to that for UAN low N rates (Table 7), but that was likely a random applications at 45 kg N ha 1. Increased awn burn was effect. Preflowering application of AS at Stillwater sigobserved with increasing rates of UAN, but even at 45 nificantly increased yields above the check in 2000 (Ta- kg N ha 1, there was little visual effect on spikelet or ble 8). Maximum grain yields were generally observed leaf color. Differences between UAN and AS applied when N, as UAN, was applied postflowering at rates either pre- or post flowering at the 22 kg N ha 1 rate between 22 and 34 kg N ha 1 although differences were were not consistent for any of the dependent variables small. analyzed. Nitrogen Uptake Yield Similar to grain yield data, only limited differences yield increases due to foliar applications of N in grain N uptake were observed in any year at both were not consistent over years and locations. sites. At Stillwater in 1999, N applied as UAN preflowering yields at Perkins in 2000 were increased by 940 kg ha 1 resulted in lower grain N uptake at the low N over that of the check (no N at flowering) when UAN rates and trends for increases at the higher 34 and 45 Table 6. Treatment means for grain yield, grain N uptake, grain N, straw yield, straw N uptake, and straw N, Stillwater, OK, Source Timing N rate Yield N uptake N Yield N uptake N Check Check UAN Pre UAN Pre UAN Pre UAN Pre AS Pre UAN Post UAN Post UAN Post UAN Post AS Post SED CV, % UAN pre quad NS NS NS * ** NS UAN post lin NS NS * NS NS NS AS pre vs. UAN pre NS NS NS * * NS UAN pre vs. UAN post NS NS NS ** ** *

5 WOOLFOLK ET AL.: INFLUENCE OF LATE-SEASON FOLIAR N APPLICATIONS ON WINTER WHEAT 433 Table 7. Treatment means for grain yield, grain N uptake, grain N, straw yield, straw N uptake, and straw N, Stillwater, OK, Source Timing N rate Yield N uptake N Yield N uptake N Check Check UAN Pre UAN Pre UAN Pre UAN Pre AS Pre UAN Post UAN Post UAN Post UAN Post AS Post SED CV, % UAN pre lin NS NS * NS NS NS UAN pre quad * * NS NS NS NS UAN post lin * NS ** NS NS NS AS pre vs. UAN pre NS NS * NS NS NS AS pre vs. check NS * NS NS NS NS kgnha 1 rates (Table 7). In 2000 at Stillwater, grain 6 8). Preflowering AS treatments at Stillwater resulted N uptake increased significantly when UAN was applied in decreased grain N below that of UAN applications pre- and postflowering (increase of 21 kg N ha 1 when in 1999 and Conversely, at Perkins in 1998, pre- UAN was applied preflowering at a rate of 34 kg N flowering AS increased total grain N above UAN while ha 1 ; Table 8). In this case, NUE (N uptake treated postflowering AS decreased grain N below UAN treatminus N uptake check divided by the rate applied) was ments. It was important to find significant increases in 62% for a preflowering UAN application. total grain N from foliar applications of N under moderate Total Nitrogen in the to high soil fertility levels (Table 1) and where N was applied before planting at all sites. In all 3 yr at Perkins, total grain N showed a linear response to foliar UAN for both pre- and postflowering Yield treatments (Tables 3 5). At Stillwater in 1998 and 1999, yield responses to pre- and postflowering N a linear increase in total grain N was observed for postflowering-applied applications were variable at both sites. yield UAN while preflowering applications means were highest for postflowering treatments at of UAN increased total grain N in 1999 and 2000 (Tables rates of 11 and 22 kg N ha 1 for Perkins in 1998 and 1999, Table 8. Treatment means for grain yield, grain N uptake, grain N, straw yield, straw N uptake, and straw N, Stillwater, OK, Source Timing N rate Yield N uptake N Yield N uptake N Check Check UAN Pre UAN Pre UAN Pre UAN Pre AS Pre UAN Post UAN Post UAN Post UAN Post AS Post SED CV, % UAN pre lin NS * 0.06 NS NS NS UAN post quad NS 0.11 NS NS NS NS AS pre vs. UAN pre NS NS ** NS NS NS AS pre vs. check * NS NS NS NS NS

6 434 AGRONOMY JOURNAL, VOL. 94, MAY JUNE 2002 respectively. At Stillwater, straw yields were highest for Time of nitrogen application: Effects on winter wheat and residual soil nitrate. Soil Sci. Soc. Am. J. 59: the check in yields were quite variable over Bulman, P., and D.L. Smith protein response of spring locations and were not necessarily correlated with grain barley to high rates and post-anthesis application of fertilizer nitroyield levels. In 1999, grain and straw yield levels were gen. Agron. J. 85: similar at both sites while in 2000, straw dry matter Cassman, K.G., D.C. Bryant, A.E. Fulton, and L.F. Jackson yields were nearly double those of grain. Nitrogen supply effects on partitioning of dry matter and nitrogen to grain of irrigated wheat. Crop Sci. 32: Cooper, J.E Effects of post-planting applications of nitrogenous Nitrogen Uptake fertilizers on grain yield, grain protein content, and mottling of wheat. Queensl. J. Agric. Anim. Sci. 31: Differences in straw N uptake due to treatment were Daigger, L.A., D.H. Sander, and G.A. Peterson Nitrogen congenerally small, excluding Stillwater in At Stillwa- tent of winter wheat during growth and maturation. Agron. J. ter in 1998 (Table 6), straw N uptake ranged from 31 68: to 67 kg N ha 1, far greater than that observed in other Dhugga, K.S., and J.G. Waines Analysis of nitrogen accumula- tion and use in bread and durum wheat. Crop Sci. 29: site-years. In 1999 at Stillwater, straw N uptake was Ellen, J., and J.H.J. Spiertz Effects of rate and timing of nitrogen greatest when foliar N was applied preflowering as UAN dressings on grain yield formation of winter wheat (T. aestivum at a rate of 45 kg N ha 1 (Table 7). Similar to grain L.). Fert. Res. 1: yield and grain N uptake data, only limited differences Finney, K.F., J.W. Meyer, F.W. Smith, and H.C. Fryer Effect in straw N uptake were observed over the 3-yr period of foliar spraying on Pawnee wheat with urea solutions on yield, protein content, and protein quality. Agron. J. 49: at both sites. Fowler, D.B., and J. Brydon No-till winter wheat production on the Canadian Prairies: Timing of nitrogen fertilization. Agron. Total Nitrogen J. 81: Gauer, L.E., C.A. Grant, D.T. Gehl, and L.D. Bailey Effects Total straw N results were highly variable. At Perkins, of nitrogen fertilization on grain protein content, nitrogen uptake, significant linear trends were observed with postflow- and nitrogen use efficiency of six spring wheat (Triticum aestivum ering UAN applications in 1998 and preflowering UAN L.) cultivars, in relation to estimated moisture supply. Can. J. Plant Sci. 72: applications in 1999 and In 1998, preflowering Gooding, M.J., and W.P. Davies Foliar urea fertilization of AS treatments resulted in higher total straw N than cereals: A review. Fert. Res. 32: preflowering UAN applications at Perkins (Table 3). At Griffiths, M.W., and P.S. Kettlewell Late-season foliar-applied Stillwater in 1998, postflowering applications of UAN sulfur and breadmaking quality of winter wheat. Aspects Appl. Biol. 25: increased total straw N over UAN applied preflowering Hunter, A.S., and G. Stanford Protein content of winter wheat (Table 6). in relation to rate and time of nitrogen fertilizer application. Agron. J. 65: Kelley, K.W Rate and time of nitrogen applications for wheat CONCLUSIONS following different crops. J. Prod. Agric. 8: Large, E.C Growth stages in cereals. Plant Pathol. 3: Foliar burn as a result of applying UAN pre- and/ Lutcher, L.K., and R.L. Mahler Sources and timing of spring or postflowering was generally not observed. Limited topdress nitrogen on winter wheat in Idaho. Agron. J. 80: tissue damage with AS was seen compared with UAN. Martin del Molino, I.M Relationship between wheat grain protein yield and grain yield, plant growth, and nutrition at anthesis. Averaged over years and locations, grain N increased when UAN was applied either post- or preflowering. J. Plant Nutr. 14: Mascagni, H.J., Jr., and W.E. Sabbe Late spring nitrogen appli- No consistent increases or decreases from foliar N applications on wheat on a poorly drained soil. J. Plant Nutr. 14: cations (pre- or postflowering) were observed for grain yield, straw yield, or straw N. Averaged over years and Olson, R.V., and C.W. Swallow Fate of labeled nitrogen fertilizer applied to winter wheat for five years. Soil Sci. Soc. Am. locations, UAN applied preflowering and postflowering at 34 kg N ha 1 increased grain N content by 2.7 and J. 48: Raun, W.R., and G.V. Johnson Improving nitrogen use effi- 2.4gkg 1, respectively. protein averaged over ciency for cereal production. Agron. J. 91: years and locations in control plots was 14.9% compared SAS Institute The GLM procedure. p In SAS/STAT with 16.5 and 16.3%, respectively, for preflowering and user s guide ed. SAS Inst., Cary, NC. postflowering UAN applied at 34 kg N ha 1. Foliar Schepers, J.S., D.D. Francis, and M.T. Thompson Simultaneous N applications just before and following flowering can determination of total C, total N, and 15 N on soil and plant material. Commun. Soil Sci. Plant Anal. 20: significantly enhance grain N content and, thus, percent Sowers, K.E., W.L. Pan, B.C. Miller, and J.L. Smith Nitrogen protein in winter wheat. use efficiency of split nitrogen applications in soft white winter wheat. Agron. J. 86: REFERENCES Spiertz, J.H.J Agronomical and physiological aspects of the role of nitrogen in yield formation of cereals. Plant Soil 75: Bänziger, M., B. Feil, J.E. Schmid, and P. 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