Meadow Fescue, Tall Fescue, and Orchardgrass Response to Nitrogen Application Rate

Geoffrey E. Brink and Michael D. Casler, USDA-ARS, United States Dairy Forage Research Center, 1925 Linden Drive West, Madison, WI 53706

Abstract

Nitrogen has a greater effect on grass growth than any other factor except moisture and temperature. As N costs continue to increase, understanding grass response to nitrogen will help producers determine the most appropriate application rate. Five N rates (0, 60, 120, 180, and 240 lb/acre) were split-applied to meadow fescue, soft-leaf tall fescue, and orchardgrass in three equal applications at two Wisconsin locations in 2005 and 2006. Plots were harvested to a four-inch stubble when sward height reached 10 to 12 inches to represent a typical defoliation scheme for managed grazing. Annual yield and herbage protein concentration of all varieties increased linearly as N application rate increased in all environments. In contrast, N-use efficiency (yield produced per unit of N applied) increased from 15 lb DM/lb N to 20 lb DM/lb N as rate increased from 60 to 120 lb/acre/year, but declined as N rate increased above 120 lb/acre/year. Although meadow fescue varieties produced less annual yield than tall fescue and orchardgrass by the second year, meadow fescue varieties generally had greater cell wall digestibility at each harvest.

Introduction

With the exception of moisture and temperature, nitrogen is the most important factor influencing growth of temperate perennial grass pastures. Although N can be provided by seeding legumes or by applying livestock manure, producers may be unable to grow or unwilling to manage legumes, lack sufficient manure to meet yield goals, or feel that N fertilizer produces more dependable grass growth. The positive growth response of non-irrigated temperate grasses to N fertilization rate has been extensively documented in the Midwest and Northeast. The general yield response of Kentucky bluegrass (Poa pretensis L.), orchardgrass (Dactylis glomerata L.), reed canarygrass (Phalaris arundinacea L.), smooth bromegrass (Bromus inermis Leyss.), tall fescue [Schedonorus phoenix (Scop.) Holub], and timothy (Phleum pretense L.) harvested as hay is linear as N rate increases to 150 or 200 lb/acre (6,8,12,17). Depending on the species and environment, yield begins to plateau or decline as N rate increases above 200 lb/acre. Given the response of grass to N rate and the rapidly-increasing cost of N fertilizer, producers must carefully consider their production requirements in order to efficiently manage this input.

Tall fescue and orchardgrass generally constitute a significant proportion of the grasses grown in pastures and hay lands within their area of adaptation (13,15). Recently-released tall fescue varieties possessing a soft or fine leaf trait are intended to have the productivity and persistence of conventional tall fescue varieties but have improved animal acceptance as well. Meadow fescue [Schedonorus pratensis (Huds.) P. Beauv.] is a temperate, perennial grass adapted to the lowlands of central and northern Europe and highlands of southern Europe. Meadow fescue has excellent potential for management intensive rotational grazing systems in adapted regions of North America (5). Although meadow fescue forage quality and palatability are frequently superior to tall fescue and orchardgrass (2,4), it is currently not widely utilized in the United States. Our objective was to compare the yield and quality response of meadow fescue, tall fescue, and orchardgrass to N rate under a harvest regime similar to grazing in terms of defoliation height and frequency.

Grass Establishment, Fertilization, and Harvest

The experiment was conducted at the University of Wisconsin Lancaster Agricultural Research Station (42.85°N, 90.71°W) on a Rozetta silt loam (fine-silty, mixed, superactive, mesic Typic Hapludalf) and at the University of Wisconsin Marshfield Agricultural Research Station (44.65°N, 90.13°W) on a Withee silt loam (fine-loamy, mixed, superactive, frigid Aquic Glossudalf) that tested high in all major nutrients. In April, 2004, ‘Bartura,’ ‘Hidden Valley,’ and ‘Azov’ meadow fescue, ‘Barolex’ soft-leaf tall fescue, and ‘Bronc’ orchardgrass were broadcast at 10 lb pure live seed per acre in 4- by 9-ft plots on a prepared seedbed. Plot size was dictated by the limited availability of Hidden Valley and Azov meadow fescue seed. The experimental design was a split-plot arrangement of a randomized complete block design with N application rate as the whole plot (five rates) and grass variety as the subplot in four replicates. To reduce the potential effect of differential N rate on adjacent whole plots, a 4-ft alley of ‘Phoenix’ turf-type tall fescue surrounded each whole plot. In the seeding year, plots were fertilized with 40 lb N per acre as ammonium nitrate in June and August, and clipped at a 4-inch stubble height every 30 days.

In 2005 and 2006, plots were fertilized with 0, 20, 40, 60, or 80 lb N per acre as ammonium nitrate in late April before the first harvest and immediately after the second and fourth harvests (0, 60, 120, 180, and 240 lb N per acre per year). Plots were harvested from May to October whenever mean sward height reached 10 to 12 inches (total of six harvests) using a rotary mower equipped with a catch basket. Forage DM yield was determined by cutting a 20-inch swath at a 4-inch stubble height through the center of each plot. A one-half to one pound subsample was taken from each yield sample, dried at 150°F for 48 h, weighed to determine DM content, and ground to pass a 1-mm Wiley mill screen. After thorough mixing, a 2-oz subsample was stored in a plastic bottle.

Forage Quality Analysis

Ground samples were analyzed for crude protein (CP), neutral detergent fiber (NDF), and in vitro neutral detergent fiber digestibility (NDFD) by calibrated near infrared reflectance spectroscopy. Herbage N (CP = N × 6.25) was measured by the Dumas method (1), NDF by the method of Mertens (9), and NDFD by the method of Goering and Van Soest (7). Calibration statistics were the following: N, standard error of prediction corrected for bias SEP(C) = 0.9 and R² = 0.98; NDF, SEP(C) = 1.50, and R² = 0.95; and NDFD, SEP(C) = 2.98, and R² = 0.70.

Nitrogen-use efficiency, or the annual DM yield produced per unit of N applied (lb DM/lb N) = (DM yield at N₆₀, N₁₂₀, N₁₈₀, N₂₄₀ lb/acre – DM yield at N₀ lb/acre) / N applied.

Statistical Analysis

Data were analyzed by the Mixed Models procedure of SAS with block assumed to be a random effect, and year, location, N rate, and grass variety assumed to be fixed effects. The Mixed Models procedure was also used to determine the significance (P ≤ 0.05) of regressions describing the response of annual DM yield and N-use efficiency to N rate, to estimate regression coefficients, and to test differences among the means and slopes of the regressions. Variety means for annual DM yield and individual-harvest forage quality were compared using Fisher's LSD (P ≤ 0.05).

Yield and Quality Response to N Application Rate

All grasses had a similar yield and quality response to N application rate at Lancaster and Marshfield when harvested at a vegetative stage in both years (no interaction between variety and N rate). In studies where a differential response to N rate was found (6,8,17), orchardgrass, smooth bromegrass, Kentucky bluegrass, and timothy were cut infrequently (three times per year) for hay. At hay stage, total yield is influenced largely by yield of the stem fraction, which differs significantly among temperate grasses (Brink and Casler, unpublished data). Nitrogen application rate did interact with location and year, but from a practical perspective the effect of year on yield response to N rate was minimal; at both locations in 2005 and 2006, annual yield increased linearly as N rate increased from 0 to 240 lb/acre (Fig. 1). While climate at the two locations differs (4546 growing degree days base 40 at Lancaster vs. 4193 growing degree days base 40 at Marshfield), differences in mean annual yield at Lancaster (4360 and 3960 lb/acre in 2005 and 2006, respectively) compared with Marshfield (3420 and 2980 lb/acre in 2005 and 2006, respectively) were more likely due to below-normal precipitation at Marshfield during most of the growing season (Fig. 2).

Fig. 1. Annual DM yield as influenced by N application rate during two years at Lancaster and Marshfield, WI (mean of five temperate perennial grass varieties).

Fig. 2. Monthly average (1970-2000) and actual precipitation during two years at Lancaster and Marshfield, WI.

Although annual yield was increased by greater N rates, N-use efficiency (yield produced for each unit of N applied) declined with higher N rates. At both Lancaster and Marshfield, N-use efficiency increased as N rate increased from 60 to 120 lb/acre in both years (Fig. 3). As N rate increased above 120 lb/acre, however, N-use efficiency declined or was unchanged, indicating little or no agronomic return for each unit of N applied above that level. Another consequence of increased application rate is the potential loss of N to the environment. Bussink (3) found that as N application rate to rotationally grazed pastures increased up to 445 lb/acre, N excretion and ammonia volatilization also increased, reducing the amount of recycled N available for subsequent grass growth.

Fig. 3. Nitrogen-use efficiency as influenced by N application rate during two years at Lancaster and Marshfield, WI (mean of five temperate perennial grass varieties).

As Wilson and colleagues (16) found in orchardgrass harvested for hay, N application rate had no effect on herbage NDF, which was lowest at first harvest in the spring (mean of 37.1% at Lancaster and 43.4% at Marshfield) and greatest in the summer (mean of 53.5% at Lancaster and 56.4% at Marshfield). As expected, herbage CP at every harvest exhibited a positive linear response to N rate at both locations in both years, increasing from 12 to 16% at 0 lb/acre to 18 to 24% at 240 lb/acre (0.01 to 0.03% CP/lb N). Herbage NDFD also exhibited a positive linear response to N rate at each harvest, increasing from 70 to 80% at 0 lb/acre to 74 to 85% at 240 lb/acre (0.01 to 0.02% NDFD/lb N), except harvests made in late summer when no relationship existed between N rate and NDFD. Previous work with smooth bromegrass, however, has shown that compared with maturity, N fertilization has a small effect on extent of fiber digestion in situ (10).

Yield and Quality Differences Among Grass Varieties

Mean annual yield of the five grass varieties varied with year and location. The range in annual yield from the most to the least productive variety was only 560 and 340 lb DM/acre at Lancaster and Marshfield, respectively, in 2005, but was 1310 and 800 lb DM/acre at Lancaster and Marshfield, respectively, in 2006. Azov meadow fescue provided greater yield than all other varieties except Bronc orchardgrass at Lancaster in 2005, with few or no differences measured among the other varieties (Table 1). In 2006, however, Barolex tall fescue and Bronc orchardgrass had greater yield than all the meadow fescue varieties. Casler et al. (4) also reported that among 15 tall fescue, 18 orchardgrass, and 7 meadow fescue varieties, tall fescue and orchardgrass provided greater annual yield than meadow fescue.

Table 1. Annual yield of five temperate perennial grass varieties grown at two Wisconsin locations for two years (mean of five N application rates).

Grass variety	Lancaster			Marshfield
	2005	2006	2-yr total	2005	2006	2-yr total
	Yield (lb DM/acre)
Bartura meadow fescue	4070	3430	7500	3440	2610	6050
Hidden Valley meadow fescue	4170	3480	7650	3400	2860	6260
Azov meadow fescue	4630	3790	8420	3640	2830	6470
Barolex tall fescue	4310	4740	9050	3330	3200	6530
Bronc orchardgrass	4620	4340	8960	3300	3410	6710
LSD (P ≤ 0.05)	210	370	—	180	160	—

Few differences in herbage CP and NDF were found among the grasses at either Lancaster or Marshfield in both years (data not shown). Average CP was greatest in early fall (18.7%) and lowest in early summer (13.3%), while average NDF was greatest in late summer (54.9%) and lowest in early spring (40.2%). The only difference among grasses occurred in late summer, when tall fescue CP was 2% lower and NDF was 2 to 4% greater than the other grasses. Significant differences were found among grasses at both locations in both years (the year × location interaction was significant) in herbage NDFD, which has been shown to be positively associated with dry matter intake and milk yield of dairy cows (11). All meadow fescue varieties had greater NDFD than tall fescue and orchardgrass at a majority of harvests at Lancaster (Fig. 4) and Marshfield (Fig. 5) in both years, and Hidden Valley meadow fescue had greater NDFD than tall fescue and orchardgrass at every harvest except two of the 23 total harvests made at both locations in both years.

Fig. 4. Neutral detergent fiber digestibility of five grass varieties at each harvest in 2005 and 2006 at Lancaster, WI (mean of five N application rates).

Fig. 5. Neutral detergent fiber digestibility of five grass varieties at each harvest in 2005 and 2006 at Marshfield, WI (mean of five N application rates).

Conclusions

Regardless of the source of N (manure, legumes, fertilizer), grass pastures that are subject to managed intensive rotational grazing generally require adequate levels of this nutrient in order to produce forage for animal consumption. Applying inorganic N fertilizer is a very reliable means of stimulating grass growth, but the increasing cost of this input dictates that producers apply it prudently. Our results indicate that when grass is harvested at a height and frequency similar to grazing and N application is split over the growing season, the efficiency of N utilization by meadow fescue, tall fescue, and orchardgrass reaches a maximum at approximately 120 lb N per acre. Greater annual application rates produce more forage, but at a diminishing return to the producer.

In addition to application rate, producers should also consider timing of N application and potential recycling. Stout and Jung (14) found that when N was applied in April and July, orchardgrass growth and N recovery was greatest in the spring. While spring application of N takes advantage of rapid growth during the reproductive phase of the grass, and favorable moisture and temperature conditions, forage production may exceed animal utilization and some forage may need to be harvested and conserved. Finally, producers should consider that some N is returned to the pasture by the grazing animal in manure and in senescing leaves and roots. The quantity of N and the extent to which it is available for plant growth is influenced by several factors, including grazing management (stocking rate and grazing height), distribution of urine and feces, N status of the grass or presence of legumes, N losses due to leaching or volatilization, and the type and quantity of supplemental feed provided to animals.

Our results also confirm previous findings that although meadow fescue is slightly less productive than tall fescue and orchardgrass (4), the yield and superior forage quality of this grass warrants its consideration for managed intensive rotational grazing systems in temperate regions.

Literature Cited

1. Bremner, J. M. 1996. Nitrogen — total. Page 1085-1121 in: Methods of Soil Analysis: Part 3, Chemical Methods. D. L. Sparks, ed. Book series no. 5. SSSA and ASA, Madison, WI.

2. Brink, G. E., Casler, M. D., and Hall, M. B. 2007. Canopy structure and neutral detergent fiber differences among temperate perennial grasses. Crop Sci. 47:2182–2189.

3. Bussink, D. W. 1994. Relationships between ammonia volatilization and nitrogen fertilizer application rate, intake and excretion of herbage nitrogen by cattle on grazed swards. Fert. Res. 111-121.

4. Casler, M. D., Undersander, D. J., Fredericks, C., Combs, D. K., and Reed, J. D. 1998. An on-farm test of perennial forage grass varieties under management intensive grazing. J. Prod. Agric. 11:92-99.

5. Casler, M. D., and van Santen, E. 2001. Performance of meadow fescue accessions under management-intensive grazing. Crop Sci. 41:1946-1953.

6. George, J. R., Rhykerd, C. L., Noller, C. H., Dillon, J. E., and Burns, J. C. 1973. Effect of N fertilization on dry matter yield, total-N, N recovery, and nitrate-N concentration of three cool-season grass species. Agron. J. 65:211-216.

7. Goering, H. K., and Van Soest, P. J. 1970. Forage fiber analyses (apparatus, reagents, procedures, and some applications). Agric. Handb. 379. USDA-ARS, Washington, DC.

8. Hall, M. H., Beegle, D. B., Bowersox, R. S., and Stout, R. C. 2003. Optimum nitrogen fertilization of cool-season grasses in the northeast USA. Agron. J. 95:1023-1027.

9. Mertens, D. R. 2002. Gravimetric determination of amylase-treated neutral detergent fiber in feeds with refluxing in beakers or crucibles: Collaborative study. J. AOAC Inter. 85:1217-1240.

10. Messman, M. A., Weiss, W. P., and Erickson, D. O. 1991. Effects of nitrogen fertilization and maturity of bromegrass on in situ ruminal digestion kinetics of fiber. J. Anim. Sci. 69:1151-1161.

11. Oba, M., and Allen, M. S. 1999. Evaluation of the importance of the digestibility of neutral detergent fiber from forage: Effects on dry matter intake and milk yield of dairy cows. J. Dairy Sci. 82:589-596.

12. Ramage, C. H., Eby, C., Mather, R. E., and Purvis, E. R. 1958. Yield and chemical composition of grasses fertilized heavily with nitrogen. Agron. J. 50:59-62.

13. Sleper, D. A., and West, C. P. 1996. Tall fescue. Pages 471-502 in: Cool-season Forage Grasses. L. E. Moser, ed. Agron. Monogr. 34. ASA, CSSA, and SSSA, Madison, WI.

14. Stout, W. L., and Jung, G. A. 1992. Influences of soil environment on biomass and nitrogen accumulation rates of orchardgrass. Agron. J. 84:1011-1019.

15. van Santen, E., and Sleper, D. A. 1996. Orchardgrass. Pages 503-534 in: Cool-season Forage Grasses. L. E. Moser, ed. Agron. Monogr. 34. ASA, CSSA, and SSSA, Madison, WI.

16. Wilson, R. G., Orloff, S. B., Lancaster, D. L., Marcum, D. B., and Drake, D. J. 2008. Assessing nitrogen fertilization needs for irrigated orchardgrass in the intermountain region of California. Online. Forage and Grazinglands doi:10.1094/FG-2008-0618-01-RS.

17. Zemenchik, R. A., and Albrecht, K. A. 2002. Nitrogen use efficiency and apparent nitrogen recovery of Kentucky bluegrass, smooth bromegrass, and orchardgrass. Agron. J. 94:421-428.