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Production Papers

Planting Date Effects on Winter Triticale Dry Matter and Nitrogen Accumulation

^a Dep. of Agron., Iowa State Univ., Ames, IA 50011
^b USDA-ARS Natl. Soil Tilth Lab., Ames, IA 50011

^* Corresponding author (lgibson{at}iastate.edu)

Received for publication January 7, 2005.

	ABSTRACT

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION REFERENCES

 
Addition of triticale (xTriticosecale Wittmack) into more diversified cropping systems could provide valuable economic and environmental benefits to producers in the U.S. Corn and Soybean Belt. To maximize triticale value, research was conducted to identify planting dates that allowed maximum dry matter production and N capture. Winter triticale was planted at 10-d intervals from 15 September to 15 October at three Iowa locations: central, northeast, and southwest for two growing seasons: 2002–2003 and 2003–2004. Aboveground dry matter production, N concentration, and N removal were greater at southwest Iowa than central and northeast Iowa. Dry matter production decreased as planting was delayed from late September to late October. Nitrogen accumulation at any time during the spring and summer was greater for September- than October-planted triticale in 2002–2003. At the end of the 2002–2003 season, mid-September-planted triticale had accumulated 37% more N than mid-October-planted triticale. In 2003–2004, total N capture occurring by early May was less for late-October-planted triticale than the other three planting dates, but there were no differences in N capture among the four planting dates from late May until maturity. Dry matter production was greatest when at least 300 growing degree days (GDDs) (base 4°C) accumulated between planting and 31 December. These results suggest that triticale should be planted in September to maximize spring forage yield and N accumulation although later planting dates would provide a higher quality forage if harvest was not delayed into late spring and summer.

Abbreviations: GDD, growing degree day

	INTRODUCTION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION REFERENCES

 
ADDITION OF TRITICALE into more diversified cropping systems for the U.S. Corn and Soybean Belt could reduce soil erosion (Dabney, 1998; Kaspar et al., 2001), capture residual soil N (Meisinger et al., 1991; Meisinger and Delgado, 2002), provide high quality forage for extended grazing periods (Baron et al., 1999; Lyon et al., 2001), and provide an additional grain crop. Soils are generally fallow during late fall and early spring in the corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] cropping system used on most of the row crop acres in this region. This increases the potential for erosion, mineralization of N, and leaching of residual nitrate. Successful utilization of the late-fall and early-spring periods requires that a crop be able to establish rapidly and grow vigorously under the cool conditions that occur after harvest of summer crops (Dinnes et al., 2002). Rapid crop establishment would protect against soil erosion that becomes problematic following crops that leave the soil with little residue cover, such as corn silage, soybean, and vegetable crops. Ample growth could also capture excess plant available N left after primary crops and decrease the potential of NO₃ leaching into ground water. In studies done with rye (Secale cereale L.) cover crops, reductions in the mass of leached N ranged from 59 to 77% compared with no cover crop (Meisinger et al., 1991). Production of winter triticale could provide fall and spring forage supplies when other sources are unavailable (Lyon et al., 2001) and allow grain to be harvested and used as a high quality swine feed (Bruckner et al., 1998). To capture these potential benefits from triticale, proper agronomic production practices must be determined.

Planting date is one of the most important management factors involved in producing high-yielding small grains (McLeod et al., 1992; Dahlke et al., 1993). However, growers may have to delay seeding of winter small grains until after the optimal date to accommodate harvest of preceding full-season summer crops. Numerous studies show that delayed planting of winter wheat (Triticum aestivum L.) decreased forage yields in the subsequent spring and summer (Corns, 1959; Thill et al., 1978; Baron et al., 1999). When seeding of winter wheat in Alberta was delayed from late August to late September, forage yield at the dough stage was reduced by 30% (Corns, 1959). Winter wheat planted in early September in Washington had shoot weights at anthesis that were 13 Mg ha^–1 greater than wheat planted one month later (Thill et al., 1978). Baron et al. (1999) concluded that early fall seeding of winter wheat, triticale, and rye in Alberta resulted in earlier forage availability and spring dry matter yield was closely related to GDDs from seeding to freeze-up in the fall.

When harvesting small grains for forage, a compromise must be made between quality and quantity since yield and nutrient levels are greatly influenced by plant maturity. As small grains mature, fiber concentration increases while crude protein concentration decreases (Bolsen, 1984), resulting in reduced feeding value. Wheat N concentration has been shown to decrease with time during the growing season because of slower N assimilation rates relative to C (Knowles and Watkin, 1931; Daigger et al., 1976). Crude protein concentration in winter wheat forage grown in Nebraska averaged 310 g kg^–1 (49.6 g N kg^–1) at fall harvest and spring jointing but dropped to 170 g kg^–1 (29.8 g N kg^–1) when harvested at boot stage (Lyon et al., 2001). Date of planting has a significant effect on crude protein levels in wheat forage. Winter wheat planted early (23 to 28 August) had lower crude protein at all harvest stages than subsequent planting dates (3 to 9, 10 to 19, and 21 to 30 September), which tended to have similar crude protein levels (Lyon et al., 2001).

Winter triticale has potential to be a valuable grain, forage, and/or cover crop in the U.S. Corn and Soybean Belt because it contains valuable traits from its parent species, wheat and rye, that allow for production of quality forage and grain while limiting soil erosion and N leaching. However, there are few established agronomic guidelines for growing winter triticale in this region. Proper planting date may be one of the most important factors determining the success of winter triticale because of the rapid temperature decline following harvest of full-season summer annuals. The objectives of this study were to determine adaptation of winter triticale in Iowa and optimum planting dates for dry matter production and total seasonal N accumulation.

	MATERIALS AND METHODS

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION REFERENCES

 
Winter triticale was grown during the 2002–2003 and 2003–2004 seasons at three Iowa locations. Trials were conducted in central Iowa at the Iowa State University (ISU) Bruner Farm near Ames (42° N, 93°36' W), the ISU Northeast Research and Demonstration Farm near Nashua (43° N, 92°30' W), and in southwest Iowa at the USDA Deep Loess Research Station near Treynor (41°12' N, 95°36' W) in 2002–2003 or at the ISU Armstrong Research and Demonstration Farm near Lewis (41°18' N, 95°6' W) in 2003–2004. Predominate soil types were Nicollet loam (fine-loamy, mixed, mesic Aquic Hapludolls) at the Bruner Farm, Kenyon loam (fine-loamy, mixed, mesic Aquic Hapludolls) at Nashua, Monona silt loam (fine-silty, mixed, mesic Typic Hapludolls) at Treynor, and Marshall silty clay loam (fine-silty, mixed, mesic Typic Hapludolls) at Lewis.

Triticale was seeded using a no-till drill (Tye model 2007, AGCO Corp., Lockney, TX) with 10 rows spaced 20.3 cm apart. Soybean was the previous crop at all locations. No tillage was performed unless previous production practices left the soil surface unsuitable for planting. Minimum tillage (field cultivation) was performed at Treynor in 2002–2003 and Lewis in 2003–2004. The seeding rate was 330 seeds m^–2 for all years and locations. Plot size was 5.9 by 15.2 m. Targeted planting dates were 15 September, 25 September, 5 October, and 15 October. Actual planting dates are listed in Table 1. Due to late soybean harvest at Nashua in 2002, only the latter three dates could be planted. In 2002–2003, cultivars Trical 815 and DANKO Presto were planted at Ames and Nashua while only Trical 815 was planted at Treynor. For 2003–2004, Trical 815 and DANKO Presto were planted at Ames, Nashua, and Lewis. Nitrogen fertilizer, in the form of urea, was applied at 56 kg ha^–1 at all locations during the spring 2002 before initial green-up of the triticale. In spring 2004, 39 kg ha^–1 of ammonium nitrate was applied at Lewis because soybean residue was removed before planting.

Data Collection
Spring dry matter samples were taken starting the first week of May and every 3 wk thereafter (Table 1). Two 0.203-m² samples cut 2.5 cm above the soil surface were taken from each plot, combined, dried at 60°C for 48 h, and weighed to determine dry matter production of each plot. Plots were staged according to Zadoks et al. (1974) at each dry matter sampling date.

Grain was harvested with combines, equipped with on-board electronic weighing systems, from areas ranging from 3.66 to 4.57 m wide by 15.24 m long, depending on the combine platform size. Grain subsamples (approximately 2000 g) were taken during the combine harvest to determine moisture concentration. Moisture concentration was determined using a grain analysis computer (Model GAC2100, Dickey-John, Auburn, IL). Final grain yields were adjusted to 135 g kg^–1 moisture. Straw samples were collected from the swath created by the combine.

Subsamples (100 g) from spring dry matter samples were analyzed for N and C concentration. Straw (100 g) and grain (20 g) samples were analyzed for N and C. Dry matter and straw samples were ground first in a Wiley mill (Arthur Thomas Co., Philadelphia, PA) fitted with a 3.0-mm screen. The dry matter and straw samples were further ground using a UDY cyclone sample mill (Model 3010-030, UDY Corp., Fort Collins, CO) fitted with a 1.0-mm screen. Grain samples were ground once using the UDY cyclone sample mill. Nitrogen and C concentration of the samples were determined by combusting 200 mg at 950°C in a LECO (Model CHN-2000, LECO Corp., St. Joseph, MI) analyzer (AOAC Int., 2000, p. 26–27).

Statistical Design and Analysis
The experimental layout was a randomized complete block with four replications. Data was analyzed within years using SAS (SAS Inst., Inc., Cary, NC). Two- and three-way interactions of location, planting date, and cultivar were analyzed for 2003–2004. Interactions were not analyzed for 2002–2003 because of missing data for Trical 815 at the southwest location and mid-September planting at the northeast location. Statistically significant interactions were subjected to further ANOVA using the slice command of Proc Mixed.

Repeated measurements of dry matter, N concentration, and N accumulation for individual experimental units were used to predict response to thermal time in 200-GDD increments using Proc Mixed (Littell et al., 1996). A second-order polynomial line was fit to dry matter and N accumulation responses to thermal time. A Type III exponential function (Sit and Poulin-Costello, 1994) was used to fit N concentration response to thermal time. Predicted experimental unit values at each 200-GDD increment were compared for statistical significance using an F test. Proc Mixed was also used to compute F tests for main effects of location, planting date, and cultivar on grain yield, grain N concentration, grain N accumulated, and straw N concentration. Tukey's test was used to make mean comparisons for significant main effects (Steel and Torrie, 1980).

Relative dry matter yields for both seasons of the study were calculated as a percentage relative to the mean of the highest-yielding planting date within a location and growing season. The critical amount of GDDs needed to obtain maximum relative dry matter production was determined by the procedure described by Cate and Nelson (1971). Proc Reg of SAS was used to fit lines to the populations on each side of the critical level of GDDs obtained from the Cate–Nelson test. Significance level for all statistical tests was P = 0.05.

	RESULTS AND DISCUSSION

TOP ABSTRACT INTRODUCTION MATERIALS AND METHODS RESULTS AND DISCUSSION REFERENCES

 
Weather Conditions
Climatic conditions (Tables 2 and 3) were more favorable for high triticale forage and grain yields during 2002–2003 than 2003–2004. The 2003–2004 growing season was predominated by cool and moist conditions that increased the presence of Septoria leaf blotch (Septoria spp.) at all locations. Mean fall temperatures were slightly below normal, and fall precipitation was near normal in both 2002 and 2003. Early growing conditions were near normal in the spring of each year. Temperatures during grain fill (June to mid-July) were normal in 2003 and below normal in 2004. Precipitation during the period of May to mid-July was above normal both seasons. However, the bulk of the precipitation for this period occurred in early May for 2003 while it came in mid-May and continued to be above normal through June in 2004.

View larger version (37K): [in this window] [in a new window]   Fig. 1. Location effects on spring and summer dry matter accumulation, N concentration, and N removal of winter triticale in Iowa during two growing seasons. Growing degree days were calculated from 1 March using a base temperature of 4°C.

View larger version (40K): [in this window] [in a new window]   Fig. 2. Planting date effects on spring and summer dry matter accumulation, N concentration, and N removal of winter triticale in Iowa during two growing seasons. Growing degree days were calculated from 1 March using a base temperature of 4°C.

View larger version (19K): [in this window] [in a new window]   Fig. 3. Effect of planting date on relative dry matter yield of winter triticale grown over two growing seasons at three Iowa locations. Relative yields are based on mean final dry matter yield of the highest-yielding planting date within each location and growing season. Growing degree days were calculated beginning at planting. Critical level was obtained using the Cate–Nelson test to separate the data into two populations. Regression then fitted lines to the two populations.

There was no difference in total N removal between mid-September- and late-September-planted triticale at any time in 2002–2003. Mid-September planting resulted in greater N removal than early- and late-October planting throughout the spring and summer growth period. Nitrogen removal for late-September-planted triticale was greater than early-October-planted triticale from 400 to 800 GDDs and mid-October-planted triticale from 400 to 1200 GDDs. There were no differences in total N removal between early- and mid-October-planted triticale. At the end of the 2002–2003 season, mid-September-planted triticale had accumulated 37% more N than mid-October-planted triticale. In 2003–2004, total N removal was less for late-October-planted triticale than the other three planting dates at 400 GDDs after 1 March. There were no differences in N removal among the four planting dates from 600 to 1400 GDDs.

Grain N concentration increased by 1.0 g kg^–1 when planting was delayed from late-September to mid-October in 2002–2003 (Table 5). Planting date did not significantly affect grain N concentration in 2003–2004 or straw N concentration in 2002–2003. However, straw N concentration increased with delayed planting in 2003–2004. September planting resulted in 18 and 17% greater N removal in the grain than mid-October planting in 2002–2003 and 2003–2004, respectively. Lower grain yield for mid-October- compared with September-planted triticale was a more important determinant of lower N removal than grain N concentration.

It is well known that as plants mature, N concentration, and thus protein, decreases (Daigger et al., 1976; Karlen and Whitney, 1980). This response was well represented with winter triticale in our study. Seasonal N accumulation was about 50% complete at 400 GDDs (Stage 30); however, dry matter accumulation was less than 20% complete. The continued dry matter accumulation that occurred after the majority of N uptake resulted in a dilution of plant N concentration. Nitrogen concentration decreased rapidly with each GDD increase from 400 to 800 GDDs. Nitrogen concentration declined much less with each GDD increase after 800 GDDs. Early-season N concentration was greater for late-planted triticale. Nitrogen concentration became equal for all planting dates at 800 GDDs after 1 March (Stage 65) in 2002–2003. However, differences in N concentration between mid-September- and mid-October-planted triticale occurred throughout the entire growing season in 2003–2004. The low straw N concentrations as compared with grain N were due to remobilization of N into grain that occurs during grain filling of small grains (McNeal et al., 1966; Karlen and Whitney, 1980; Bauer et al., 1987).

Cultivar Differences
The ANOVA for main effects of cultivar and interactions of cultivar with location and planting date is presented in Table 4. Trical 815 produced more dry matter than DANKO Presto throughout the spring and summer growth period at the central location in 2003–2004. The dry matter difference between the two cultivars was 0.45 Mg ha^–1 at 400 GDDs but increased steadily as GDDs accumulated and was greatest at 1400 GDDs when Trical 815 produced 1.09 Mg ha^–1 more dry matter than DANKO Presto. There were no differences in dry matter production between the two cultivars at the northeast and southwest locations. Trical 815 produced 1.67 and 0.86 Mg ha^–1 more dry matter than DANKO Presto at 1400 GDDs for the mid-September and early-October plantings, respectively. There were no differences between the two cultivars for the late-September and mid-October plantings.

Greater N concentration and grain yield for Trical 815 in 2002–2003 resulted in 41% greater grain N removal when compared with DANKO Presto. In 2003–2004, 21 and 8% more N was removed in the grain of Trical 815 than DANKO Presto at the central and southwest locations, respectively. These N removal differences were mainly due to variation in grain yield rather than N concentration. There were no differences in N removal or grain yield between the two cultivars at the northeast location.

Implications for Winter Triticale Addition to Cropping Systems
Producers wanting to get full yield potential from a subsequent full-season summer annual crop, such as corn or soybean, would need to terminate or harvest triticale by mid-May. Based on historical mean temperatures, 400, 350, and 475 GDDs have accumulated by 16 May in central, northeast, and southwest Iowa, respectively. In the current study, winter triticale planted in September at central and southwest locations was in the jointing and boot stages at 400 and 475 GDDs and produced 4 and 5 Mg ha^–1 dry matter with N concentrations of 19 and 22 g kg^–1, respectively. Dry matter accumulated by mid-May was nearly 2 Mg ha^–1 greater for September- than October-planted triticale. Delaying harvest of September-planted triticale until inflorescence emergence (Stage 50; 600 GDDs) resulted in 4.5 to 7 Mg ha^–1 dry matter in central and northeast Iowa and 8 Mg ha^–1 in southwest Iowa. The N concentration of triticale at this stage was 13 to 16 g kg^–1 in central and northeast Iowa and 17 to 20 g kg^–1 in southwest Iowa. Based on historical mean temperatures, inflorescence emergence would occur on 31 May, 5 June, and 25 May in central, northeast, and southwest Iowa, respectively. Past research suggests that planting corn or soybean on these dates in central and southwest Iowa would result in at least 90% of full yield potential (Farnham, 2001; Whigham et al., 2000). Planting corn or soybean on 5 June in northeast Iowa would provide about 80% of full yield potential.

Seasonal N accumulation in triticale dry matter serves as a measure of N removal from the soil. Nitrate leaching is most problematic on fallow soils in the early spring months when rainfall amounts are high. Therefore, the amount of residual N triticale can capture from the soil to prevent NO₃ from entering ground and surface water is important. Triticale was not tested against other species, but it appears to be efficient in N uptake during early spring. There are a couple of ways that winter triticale could be used for N capture in central USA grain cropping systems. It could be planted after harvest of summer annual crops in the fall and terminated before or shortly after planting of summer annuals in the spring. Our study indicates that winter triticale used this way could capture significant amounts of residual N. More than 50% of triticale N uptake occurred by mid-May, and nearly 75% of N uptake had occurred by late May. The full N capture potential of winter triticale could be exploited by harvesting it as a grain crop in mid- to late July. September planting would likely be required to maximize N capture of winter triticale. Planting date influenced the amount of N removal in 1 of 2 yr in our study. The impact was quite large considering that 37% more N was taken up by mid-September- than mid-October-planted triticale.

	REFERENCES

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This Article Abstract Figures Only Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Schwarte, A. J. Articles by Jannink, J.-L. Search for Related Content PubMed Articles by Schwarte, A. J. Articles by Jannink, J.-L. Agricola Articles by Schwarte, A. J. Articles by Jannink, J.-L. Related Collections Sustainable Agriculture Forage Management Crop Rotation Systems Other Forage Crops Crop Systems Nitrogen