Nitrogen Use Efficiency of Cool-Season Perennial Forage Grasses Planted With and Without Alfalfa Under Irrigation for Hay Production

Final Report for FW08-307

Project Type: Farmer/Rancher
Funds awarded in 2008: $14,999.00
Projected End Date: 12/31/2010
Region: Western
State: Wyoming
Principal Investigator:
Dr. Blaine Horn
University of Wyoming
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Project Information


‘NewHy’ hybrid wheatgrass and ‘Oahe’ intermediate wheatgrass produced the most hay with no applied nitrogen, and ‘Paiute’ orchard grass produced the least. ‘Manchar’ smooth bromegrass produced more hay per pound of nitrogen than the other grasses in 2011, whereas ‘Luna’ intermediate wheatgrass did so in 2010. However, the greatest net income at all nitrogen rates was obtained with ‘Oahe’. To ensure grass hay crude protein content is sufficient for a lactating beef cow, the grass should be fertilized with at least 50 pounds of nitrogen per acre. However, at rates above 100 pounds per acre high nitrate-nitrogen content can result.


Alfalfa produces high quality hay of good yields, but stands can be short-lived, resulting in high establishment costs and increased potential for soil erosion due to tillage. In addition, weed control options are limited, and insect, nematode and disease infestations can increase production costs and reduce yields. Alfalfa also can cause bloat in ruminant livestock and, after a hard fall freeze, few leaves are left on the stems for grazing.

Cool season grasses can produce respectable hay yields in the Western U.S., potentially for more years than alfalfa, and generally have less weed, insect, nematode and disease problems, reducing pesticide need, thus protecting the health and safety of agricultural workers. In addition, grass hay fields should maintain or enhance soil quality and productivity, as well as maintain or improve water quality.

Diversifying haying operations with cool season grasses could provide agricultural producers more management flexibility, increasing sustainability of their operations. Cool season grass hay fields could be grazed in the spring and yet produce a respectable hay crop. In addition, they could be grazed throughout the summer if needed or in the fall, after livestock are taken off native range pastures. This could greatly benefit Western U.S. ranchers, especially during drought, by providing growing season rest to their native range pastures.

Thus cool season grasses for hay production could enhance the quality of life of Western U.S. agricultural producers by reducing hay production costs (establishment and pest control), increasing management flexibility and improving land stewardship. If so, the viability of Western U.S. agricultural communities would be maintained, as these lands would remain in agricultural production instead of being sub-divided.

With rising energy costs and high fertilizer prices, it is imperative that irrigated cool season grass hay fields be managed for optimum forage production. Cool season grasses require nitrogen (N) fertilization to produce comparable yields to alfalfa and to maintain stand health and longevity. Thus N fertilizer management by Western U.S. hay producers will be important for stewardship and sustainability of their grass hay lands. Fertilizer recommendations based on a soil test for cool season perennial forage grasses are the same regardless of species. However, some of these grasses may be more nutrient use efficient with respect to N and produce more forage on less N fertilizer. If there are cool season grasses that are more N use efficient, producers could potentially lower their N fertilizer use and resultant costs without sacrificing hay yields and stand longevity.

Project Objectives:

1) Compare forage yields of cool season perennial grasses under irrigation.

2) Compare nitrogen use efficiency (NUE) of cool season perennial grasses (soil residual nitrate levels and forage yields per lb N fertilizer).


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  • Elmer Detavernier
  • Gerry Miller


Materials and methods:

Initially the study was to be conducted at the Wyoming Girls School (WGS) at Sheridan, WY. The field to be used was already in grass, primarily smooth brome and Kentucky blue, so Elmer Detavernier, the producer cooperator, disked the area in early May 2008 once the soil was dry enough. However, due to precipitation throughout May, Elmer was not able to till the area again, thus seeding was delayed until late August. Unfortunately only a few of the grasses established, so the area was tilled and reseeded in mid-May 2009, but again, the seeding was not successful. Thus it was requested for a one year extension and a site change to Mr. Gerry Miller’s near Buffalo, WY, where the same grasses, except for tall fescue and the grasses mixed with alfalfa, were already established for a pasture study.

Eight cool season perennial grasses that had been randomly seeded into 20’ x 200’ plots within three blocks on April 19, 2008 were used for this project. The grasses were ‘Paiute’ orchardgrass (OG), ‘Paddock’ meadow bromegrass (MBG),‘Manchar’ smooth bromegrass (SBG), ‘Luna’ intermediate (pubescent type) wheatgrass (IWG), ‘Oahe’ intermediate wheatgrass (IWG), ‘NewHy’ hybrid wheatgrass (HWG), ‘Hycrest’ crested wheatgrass (CWG) and ‘Bozoisky’ Russian wildrye (RWR).

On April 26, 2010, ammonium-nitrate fertilizer at 0, 50, 100, 150 and 200 lb N/ac was randomly applied to 20’ wide strips across the grass plots, resulting in 40 subplots per block. On May 2, 2011, ammonium-nitrate was randomly applied at 0, 62.5, 125, 187.5 and 250 lb N/ac to one of the five remaining 20’ wide strips not fertilized in 2010, except for the 0 lb/ac rate, in which the same strips used in 2010 were used again. The reason for the higher rates in 2011 was because it appeared that some of the grasses may not have reached their full yield potential at the 200 lb N/ac rate in 2010.

On April 15, 2010, top soil samples (0 – 12”) were collected from each grass by N rate subplot and combined within each grass for each replication (24 soil samples) to determine if soil quality components were similar among the grasses. On July 16, 2010, top soil samples were again collected from each grass by N rate subplot (120 soil samples) to determine if soil quality components were similar among the grasses and among the N rates. Soil samples were analyzed for their phosphorus, calcium, magnesium, potassium, nitrate-N and ammonium-N contents by the University of Missouri’s Soil and Plant Testing Laboratory.

On May 5, 2011 top soil samples were collected from each grass by 0 and 200 lb N/ac subplots and analyzed for their nitrate-N and ammonium-N contents to determine if these N sources were similar among the grasses and how much carryover there was in the 200 lb N/ac rate treatment.

On June 22, 2010 and July 1, 2011, forage from each grass by N rate subplot was harvested from a single 0.25 m2 hoop to a two to three inch stubble height. The nine day later harvest date in 2011 was so that the grasses were at similar stages of maturity both years. Each forage sample was weighed, sub-sample collected, weighed, dried and weighed again to determine percent dry matter. Pounds per acre of dry matter forage for each grass by N rate was then determined, however, results are reported as hay yields in T/ac (12% moisture).

The 2010 grass samples were analyzed for Acid Detergent Fiber (ADF) – used to estimate Net Energy maintenance (NEm), Neutral Detergent Fiber (NDF) – used to estimate Non-Fibrous Carbohydrates (NFC), crude protein, nitrate-N (NO3-N), Phosphorus (P), Calcium (Ca), Potassium (K), Magnesium (Mg), Sulfur (S), Iron (Fe), Manganese (Mn), Zinc (Zn), Copper (Cu) and Molybdenum (Mo). The 2011 grass samples were analyzed for ADF, crude protein and NO3-N. All samples were analyzed by Dairyland Laboratories of Arcadia, WI. The nutrient needs of a 1,400 lb early lactating beef cow (20 lb/day peak milk) are referenced to the quality components of the grasses.

Research results and discussion:

‘Bozoisky’ RWR, ‘Hycrest’ CWG and ‘NewHy’ HWG produced the most hay with no addition of fertilizer N in 2010, whereas ‘Oahe’ IWG produced the most in 2011, and it and ‘NewHy’ produced the most for the two years (Figure 1). Although the grasses were harvested nine days later in 2011 compared to 2010, they produced less hay in 2011 by an average of 0.7 T/ac, except ‘Paiute’ OG which had similar yields both years, but still had the lowest among the grasses by an average of about a T/ac. Why ‘Bozoisky’, one of the top hay producing grasses without applied N in 2010, produced less than a third the amount of hay in 2011 is not known.

Although ‘Hycrest’ CWG and ‘NewHy’ HWG produced a similar amount of hay as ‘Bozoisky’ RWR in 2010 with no applied N, they apparently did not produce more dry matter forage per pound of soil N in the form of nitrate-N (NO3-N) as ‘Bozoisky’ (Table 1). Soil NO3-N under ‘Bozoisky’ averaged 7.9 lb/ac on April 15, whereas under ‘Hycrest’ and ‘NewHy’ it was 16.6 and 18.1 lb/ac, respectively (Table 2). By July 16, soil NO3-N content under ‘Bozoisky’ and ‘NewHy’ averaged 1.2 lb/ac, and under ‘Hycrest’ it was 1.9 lb/ac, indicating ‘Bozoisky’ used 6.6 lb of soil NO3-N/ac, ‘NewHy’ 17.0 lb and ‘Hycrest’ 14.7 lb. Why soil NO3-N content under ‘Hycrest’ and ‘NewHy’ on April 15 was 7 to 9 lb/ac more compared to the other six grasses is not known, especially when it was similar among the grasses on May 5, 2011 (Table 3). In 2008 and 2009, yellow sweet clover had a significant presence in the entire grass hay field including the plot area, which may explain the fairly high soil NO3-N contents under all the grasses, but there is no reason to suspect that it had a greater density within the ‘Hycrest’ and ‘NewHy’ plots.

‘Hycrest’ CWG produced more hay than the other grasses in 2010 with 50 and 100 lb N/ac by an average of 0.8 T/ac, whereas ‘Oahe’ IWG produced an average of 1.1 T/ac more hay than the other grasses at the 150 and 200 lb N/ac rates (Figure 2). In addition, ‘Oahe’ produced the most hay at each N rate in 2011 by this same amount (Figure 3).

Except for ‘Manchar’ SBG and ‘Luna’ and ‘Oahe’ IWG, the grasses produced less hay in 2011 with higher N rates than they yielded in 2010 (Figures 2 and 3). ‘Bozoisky’ RWR and ‘Paddock’ MBG had the greatest discrepancy, producing an average of 1.0 and 0.7 T/ac less, respectively. ‘Manchar’ produced the same amount of hay both years, and ‘Luna’ and ‘Oahe’ produced an average of 0.2 T/ac more in 2011 compared to 2010. Why hay yields of the grasses were generally not greater in 2011 as compared to 2010 may have been due to the cooler May and drier mid- to late-June conditions in 2011 as compared to in 2010. Had the grasses been irrigated in mid-June 2011, they might have produced higher hay yields.

The grasses, except ‘Paiute’ OG, ‘NewHy’ HWG and ‘Hycrest’ CWG, appeared to possibly not have reached their maximum forage yield in 2010 with 200 lb N/ac rate (Figure 2), and thus, as noted in the methods section, the reason for the higher N rates in 2011. However, even with 250 lb N/ac the grasses, except possibly ‘Paddock’ MBG, ‘Manchar’ SBG and ‘Oahe’ IWG, did not appear to have reached their maximum forage yield in 2011 (Figure 3) but, as will be shown below, maximum forage yield does not necessarily result in the highest net income per acre.

'Bozoisky’ RWR may have been the most efficient in its use of available soil NO3-N in 2010 for aboveground growth compared to the other grasses, but it was the least efficient in its use of applied fertilizer N for additional forage growth both years (Table 4). Because ‘Paiute’ OG generally produced more additional pounds of hay per pound of applied N in 2010 compared to the other grasses but had the lowest hay yields, using NUE to select a grass for hay production may not be advisable. Using net income per acre is probably a better way to select which grass or grasses would be the best to use for hay production.

At $80/T for grass hay and $0.77/lb for N plus $5/ac for application, the highest net incomes in 2010 would have been obtained with ‘Hycrest’ CWG at 50 and 100 lb N/ac and with ‘Oahe’ IWG at 150 and 200 lb N/ac (Table 5). In 2011, the highest net income at each N rate was obtained with ‘Oahe’, with the best returns at the 125 and 187.5 lb N/ac rates. ‘NewHy’ HWG and ‘Bozoisky’ RWR did not produce enough additional hay with applied N to return a greater net income then what would have been received for hay with no N fertilizer in 2010 and 2011, and likewise for ‘Paiute’ OG in 2011. 'Bozoisky’ may have had the highest net income with no applied N in 2010 and ‘Oahe’ the highest in 2011, but ‘NewHy’ HWG, along with ‘Oahe’, had the highest total net income for the two years.

Although soil NO3-N and NH4-N levels on July 17, 2010 in the 200 lb N/ac rate subplots were about twice the level found in the other four N rate subplots (Table 2), these two soil N sources were only slightly higher in the 200 lb N/ac subplots compared to the 0 lb N/ac subplots on May 5, 2011 (Table 3). This would indicate that the grasses probably used this soil N during the remainder of the 2010 growing season. Unfortunately, late summer/early fall 2010 forage yields were not determined to help veriy this.

Applied N appeared to have little to no effect on the Net Energy maintenance (NEm) content of the grasses both years, though it declined in ‘Paiute’ OG and ‘Hycrest’ CWG but increased in ‘Bozoisky’ RWR as N rate increased (Table 6). ‘Paiute’ contained the highest average amount of NEm among the grasses both years, followed by ‘Bozoisky’. ‘Paddock’ MBG contained the least amount of NEm in 2010, but in 2011 it contained an average of 0.09 Mcal/lb more, and thus met the needs of a lactating beef cow (0.60 Mcal/lb). The NEm content of ‘Manchar’ SBG and ‘NewHy’ HWG were borderline sufficient in meeting the above cow’s needs in 2010, but in 2011 it was sufficient in ‘Manchar’ but again borderline sufficient in ‘NewHy’. Both ‘Luna’ and ‘Oahe’ IWG contained a sufficient amount of NEm in 2010 to meet the above cow’s needs, but in 2011 they did not, especially ‘Oahe’.

Unlike NEm, Non-Fibrous Carbohydrate (NFC - primarily starch and sugars) content appeared to decline in the grasses as applied N increased (Table 7). Apparently as the grasses produced more biomass as a result of more available N starch, sugars were being replaced with cellulotic tissue. This would explain why NEm remained fairly constant acrossed N rates. As with NEm, ‘Paiute’ OG contained the highest average level of NFC, with ‘Hycrest’ CWG, ‘Manchar’ SBG and ‘NewHy’ HWG the lowest amounts.

Crude protein content in the grasses increased at a nearly linear rate both years as applied N rate increased, except in ‘Hycrest’ CWG, 'Bozoisky’ RWR, and possibly ‘NewHy’ HWG in 2010, where it appeared to level off between 150 and 200 lb N/ac (Table 8). ‘Hycrest’ and ‘Bozoisky’ mature earlier than the other grasses, and it is possible that the higher levels of N may have resulted in them reaching maturity sooner. At 0 lb N/ac only ‘Paiute’ OG, ‘Luna’ and ‘Oahe’ IWG and ‘NewHy’ contained an adequate level of crude protein to meet a lactating beef cows’ needs (10%) in 2010, but in 2011 all the grasses, except ‘Oahe’, ‘Luna’ and ‘NewHy’ contained an adequate amount. In addition, ‘Oahe’ and ‘Luna’ also contained the least amount of crude protein over all applied N rates in 2011, whereas in 2010 they contained similar levels as the other grasses. ‘Paddock’ MBG contained significantly less crude protein compared to the other grasses in 2010 and not enough to meet the needs of a nursing cow at applied N rates at less than 100 lb/ac, but in 2011 its content was similar to the other grasses, and at the 187.5 and 250 lb N/ac rates, only ‘Bozoisky’ RWR and ‘Paiute’ OG contained more.

Why ‘Paddock’ MBG contained more NEm and crude protein in 2011 compared to 2010 and ‘Luna’ and ‘Oahe’ IWG contained less is not clear. As grasses mature, their crude protein content declines, and to some degree NEm does as well. It is possible that ‘Paddock’ was not as mature on July 1, 2011 as it was on June 22, 2010, and this may have been true for ‘Paiute’ OG and ‘Bozoisky’ RWR as well, as their crude protein content in 2011 was higher than in 2010.

However, ‘Luna’ and ‘Oahe’, and to some degree ‘NewHy’ HWG, were the main reason for the later harvest in 2011, due to them still in the boot stage the third week of June, thus their lower crude protein content is somewhat perplexing. These three grasses did grow rapidly (seedhead extension) during the last ten days of June 2011, and this may be the reason for their lower forage quality. Thus, timing of harvest of these three grasses with regard to forage quality may be more critical than for the other grasses in this project.

Besides an increase in forage due to N fertilization, increase in crude protein content of the grass hay should also be taken into account when determining the economic benefit of applying N fertilizer. As indicated above, hay of ‘Paddock’ MBG, ‘Manchar’ SBG and ‘Bozoisky’ RWR in 2010, of ‘Oahe’ IWG and ‘NewHy’ HWG in 2011, and of ‘Hycrest’ CWG both years from the 0 lb N/ac subplots did not contain a sufficient amount of crude protein to meet the needs of a lactating beef cow. Thus a protein supplement would need to be provided to make up for the deficient. If this reference cow consumed 30 lb of dry matter forage each day, she would require 3.0 lb of crude protein. Based on the crude protein content of these grasses, they would only provide between 2.25 and 2.73 lb of protein per day. If the provided protein supplement cost $0.50 per pound of protein, then the weekly cost for the supplement when hay from these grasses was the forage source would range from a high of $2.63 for the 2010 ‘Paddock’ hay to a low of $0.95 for the 2010 ‘Hycrest’ and 2011 ‘Oahe’ hay. In addition, due to 2010 hay of ‘Paddock’ from the 50 lb N/ac rate containing only 8.8% crude protein, 0.35 lb/day of protein would need to be provided the cow at a cost of $1.22 per week.

Nitrate-N (NO3-N) content in the grasses, as with crude protein, increased as applied N rate increased. At rates above 50 lb N/ac in 2010 (Figure 4) and 62.5 lb N/ac in 2011 (Figure 5), hay from the grasses contained NO3-N levels greater than what is considered safe for pregnant and breeding livestock (350 ppm) if it is their only source of forage. In addition, at 200 lb N/ac in 2010 the NO3-N content of hay from ‘Manchar’ SBG, ‘NewHy’ HWG, ‘Oahe’ IWG and ‘Paiute’ OG were at levels greater than what is considered safe for non-breeding livestock (1130 ppm) if their only source of forage. For ‘Manchar’ this dangerous level of NO3-N occurred at 150 lb N/ac in 2010. Why the NO3-N content of the grasses in 2011 averaged nearly 300 ppm less than it did in 2010 at N rates of 100 lb/ac and above is not known. However, due to the high 2010 NO3-N levels in the grasses, it is advised that grass hay should be tested for its NO3-N content if N had been applied, especially at rates exceeding 100 lb/ac and if the hay is to be fed to pregnant and breeding livestock. It is also advised to swath grasses in the afternoon instead of in the morning if they have been N fertilized, as NO3-N levels tend to decline as the day progresses. Because ‘Paiute’ and ‘Manchar’ contained the highest average levels of NO3-N at N rates at 100 lb/ac and above, it may be wise to not fertilize them with more than 100 lb N/ac.

Applied N appeared to have little effect on the phosphorus (P) content of the grasses (Table 9). In addition, P content was similar among the grasses and sufficient to meet the needs of a lactating beef cow (0.20%). However, calcium (Ca) content increased in the grasses with an increase in applied N, except in ‘Paiute’ OG where it declined. The grasses generally contained enough Ca to meet the needs of a lactating beef cow (0.30%), with ‘NewHy’ HWG and ‘Bozoisky’ RWR containing the highest levels and ‘Manchar’ SBG the least. The Ca:P ratio was generally sufficient (1.5: 1) in hay from these grasses, except for ‘Luna’ IWG and ‘Manchar’ SBG at all N rates, ‘Oahe’ IWG at rates less than 150 lb/ac and ‘Hycrest’ CWG at rates below 100 lb/ac. Thus a Ca supplement might be needed when feeding hay from these grasses to the reference cow.

Potassium (K) content increased linearly with an increase in applied N in all the grasses (Table 10). ‘Paiute’ OG and ‘Bozoisky’ RWR contained the highest levels of K and ‘Hycrest’ CWG the least. However, even at 0 lb N/ac all grasses contained more K than what a lactating beef cow needs (0.70%). With respect to magnesium (Mg),‘Paiute’ OG was the only grass that contained a sufficient amount to meet a lactating beef cow’s needs (0.20%), regardless of N rate. ‘Hycrest’ CWG contained the least amount of Mg compared to the other grasses, and Mg content appeared to increase slightly in all the grasses with an increase in applied N. ‘Paiute’ OG and ‘NewHy’ HWG contained an adequate amount of sulfur (S) to meet the needs of a beef cow (0.15%) at all N rates, whereas the other grasses may not have contained a sufficient amount at 0 lb N/ac and ‘Paddock’ MBG not enough at 50 lb N/ac.

‘Bozoisky’ RWR contained the highest average level of iron (Fe) and ‘Manchar’ SBG the least (Table 11). Application of N fertilizer resulted in a slight decrease in grass Fe content, but the grasses from all N rates contained an adequate amount of Fe for a beef cow (50 ppm). However, with regard to manganese (Mn), the more N that was applied the higher its content in the grasses, but none of them contained a sufficient amount to meet a beef cow’s requirement (40 ppm) regardless of N rate, except for ‘Paiute’ OG. In addition, none of the grasses contained an adequate amount of zinc (Zn) to meet the requirements of a beef cow (30 ppm), and N fertilizer appeared to have little effect on grass Zn content.

Applied N may have increased the copper (Cu) content in the grasses slightly over no applied N (Table 12). ‘Luna’ IWG contained the highest average amount of Cu but still did not meet the needs of a beef cow (10 ppm), except at the 200 lb N/ac rate. Fortunately the grasses contained very low levels of molybdenum (Mo), and as N fertilizer rate increased its levels declined, thus interference with Cu absorption should be minimal. ‘Paiute’ OG contained the highest average amount of Mo among the grasses, but even at its highest level at 0 lb N/ac it was less than 1 ppm.

Participation Summary

Research Outcomes

No research outcomes

Education and Outreach

Participation Summary:

Education and outreach methods and analyses:

A PowerPoint presentation was developed to share the 2010 results of this project to attendees (ag professionals and producers) at five forage seminars held throughout NE Wyoming in early April 2011. In addition, 2010 and 2011 hay yields and resultant net income from this study was shared with the Sheridan County Wyoming Stock Growers at their November 2011 meeting. Results of this project will be published in the Northeast Area Extension Connection Newsletter and the Johnson County Land & Livestock Newsletter that goes to ag producers and professionals and is posted on the University of Wyoming’s Cooperative Extension Service web site. In addition, results of the project will be published in UW Ag Experiment Station Annual Reports, posted on the UW Sheridan Research and Extension Center (SREC) website, provided to UW and Western Region Extension Educators for publication in their newsletters, and furnished to the popular agricultural press.

Education and Outreach Outcomes

Recommendations for education and outreach:

Potential Contributions

Agricultural professionals and many producers already know that fertilizing grasses with nitrogen (N) will result in an increase in forage production, and most realize that an increase in crude protein content also occurs. However, knowledge that grasses do not all respond the same to applied N may not be fully appreciated by ag professionals and producers, especially with regard to net economic return. The results of this project show that some grasses did not produce enough additional forage at any N rate to justify the expense of fertilizer, especially at current prices for hay and fertilizer. In addition, the N rate at which there becomes a diminishing net economic return is not the same for each grass, and it is often below the rate at which maximum hay yields are obtained.

Possibly the biggest contribution this project may have is making it apparent that fertilizing perennial cool season grasses with N could result in high nitrates in the forage. Ag professionals and producers are aware of the potential problem of high nitrates in hay of annual grasses, e.g. oats, barley and millet, but it is not usually a concern in hay from perennial grasses, especially at N rates at 100 lb/ac or less. Based on the results of this project, it might not be warranted to fertilize perennial cool season grasses with more than 100 lb N/ac no matter what the potential net return would be and to test all grass hays for nitrates, especially if the grass field had been fertilized with N.

The results of this project should also increase the understanding of ag professionals and producers that differences in forage quality exists among grasses, and that application of N can cause changes in some concentrations of some components.

Future Recommendations

Further work on perennial grass species and varieties for hay production and grazing needs to be conducted in this region. More producers are looking at converting alfalfa fields to perennial grass as these fields expire, and many of them want to use the grass fields for grazing. ‘Paiute’ OG performed poorly in this project, but in 2009 it produced twice the hay yield with no applied N at the 0 lb N/ac treatment. A possible reason for this may have been due to the cooler May temperatures in 2010 and 2011 compared to 2009. Thus, some cool season perennial grasses may not be suited for this region.

Although many livestock producers are aware that N fertilizer increases protein content of the forage, too many may not realize that non N fertilized grass often does not contain an adequate amount of protein for a lactating animal, especially if the grass was not hayed until seed ripening. Field demonstrations showing that the increase in hay yield between anthesis and seed ripening is small but decline in crude protein can be significant needs to be done. In addition, analysis of grass hays fertilized with different N rates and harvested at different maturities needs to be done to obtain a better understanding of when the potential for toxic levels occur. Emphasizing the need to test N fertilized grasses for nitrates needs to be done as well. Thus a continuation of providing ag producers and professionals this can of information is warranted. In addition, analysis for other quality components needs to be stressed, as amounts of some components may not be adequate or out of balance with others.

Another area that needs to be investigated is water needs of perennial cool season grasses and resultant irrigation management. This is especially warranted with respect to sprinkler type irrigation systems due to increasing energy costs.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.