Volume 21, Number 2, June 9, 1997

Greetings! Warm weather has finally returned in a big way this past week. Just in the nick of time, as alfalfa and corn both needed the heat units to get going. Many of you will have started (or perhaps finished) first crop by the time you receive this. Unfortunately, many areas of the state, particularly the East, are very dry and unable to take full advantage of the warmer temperatures. Hopefully this will change by the time you read this.

The cool weather certainly set back our first crop, and will have some effects on forage quality. Take a look at Mike Rankin’s article in this issue for some help in understanding weather effects on quality. Forage testing is the only way to know the true quality of your forage. Hay prices are still high. They will come down as summer moves on, but with first cutting late and perhaps a little light, prices will likely remain strong through this winter. It is not too soon to start considering winter feed needs. Alan Rotz has an article on cost of forage production which may help you determine how much it costs to produce your feed, and what you can afford to buy it for if need be.

Remember the WFC Forage Expo coming up June 25 and 26 at the Walter Strebe farm near Manawa in Waupaca County. We have been getting good press coverage of this event and expect a great turnout. Hope to see you there.

The spring of 1997 has been cool, and alfalfa growth is slow, but how will current or future temperature and moisture conditions impact forage quality?

"Cut alfalfa at late bud for optimum quality." We’ve heard this statement, or a similar one, many times over the past 10 to 15 years. Although forage quality is strongly correlated to morphological stage (for example, late-bud or first flower), many years of monitoring the forage quality of a standing crop has taught us that environment plays an important role in what the actual forage quality might be at a specific stage of maturity. In other words, in a given year, the forage quality at "late-bud" might still be too high for harvesting, too low for dairy quality forage or about right depending on the environment (primarily temperature and moisture) that the plants developed under. For this reason, it is important that forage producers understand the relationship between environment and forage quality.

Temperature

Temperature is the driving force behind most physiological processes that occur in a plant. These include photosynthesis, respiration, translocation of nutrients, carbon partitioning and cell wall formation. It stands to reason that changing temperature will have a dramatic impact on what goes on inside the plant. We see these effects each and every year when comparing alfalfa regrowth and forage quality in summer to that of regrowth and quality in the fall. Alfalfa can actually increase in quality over time in the fall as a result of cooler growing temperatures. This is verified in some research done by Michael Collins at Wisconsin in 1983 (Table 1).

 
 

Table 1. Alfalfa or Red Clover Quality Change During Autumn (Collins, 1983)
Harvest	Alfalfa		Red Clover
Date	IVDMD	NDF	IVDMD	NDF
	---------------------%---------------------
10/07	80.0	24.8	81.4	25.9
10/17	81.3	22.8	81.9	23.1
10/28	81.1	24.8	81.8	23.5
11/08	78.4	28.3	76.5	24.7
Previous Cut = Late August

 

In a Utah research trial, alfalfa ADF and NDF were compared from an intermountain area where night temperatures averaged 45° F. to that of a lowland where night temperatures were 70° F.

Daytime temperatures were similar in both areas. The ADF values for the alfalfa grown at the higher elevation was 28.2 percent compared to 31.9 for the alfalfa grown in the lowland. Similarly, NDF values for the high elevation alfalfa was 35.5 percent compared to 39.1 for the lowland.

As the temperature of the growing environment increases, it has the following overall effects on plant growth and forage quality.

• decreases stem diameter
• accelerates rate of maturity
• increases lignification
• decreases plant height
• decreases leaf stem ratio
• decreases digestibility

Moisture

Although somewhat secondary to temperature, soil moisture status can also have a significant impact on alfalfa growth and forage quality. Mature alfalfa is about 75 to 80 percent water. In a two ton (dry matter) per acre standing crop, this translates to eight tons of water. Yet, only one percent of the water that enters the growing plant is retained. Water (and lots of it) is essential for alfalfa growth, and any moisture deficit situation will have physiological ramifications. Drought conditions tend to delay plant maturity (if it occurs early in growth cycle), decreases plant height, increases leaf stem ratio and generally decreases NDF percent.

Final Thoughts

Key environmental factors like temperature and soil moisture status cannot be disregarded when trying to explain or predict forage quality characteristics. Making a prediction of forage quality based solely on morphological stage often is erroneous when confounding environmental conditions exist. These environmental factors are interactive. For example, the ideal growing conditions from the standpoint of forage quality impact of dry conditions would be negated by high temperatures during a hot drought when forage quality drops fast and maturity accelerates.

Environmental conditions are often the reason why forage quality is not what is expected in a harvested crop based on calendar days or stage of maturity. For this reason, knowing how these factors interact and impact forage quality can be a valuable knowledge base for forage producers.

Mike Rankin, Fond du Lac County Extension

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Forage production costs form a major portion of the total cost of milk production on dairy farms. There are many methods available to produce forage, but most can be categorized as silage, dry hay or grazing systems. For most dairies today, the primary forage is silage. Being a primary feed and a major cost, the economics of forage production can have a large influence on farm profit. Because of the many factors that influence production costs, a comprehensive analysis is needed to determine those costs. Such an analysis is best performed using DAFOSYM, a simulation model which integrates the many biological and mechanical processes on a dairy farm.

Materials and Methods

Long-term simulations with DAFOSYM were used to quantify the costs of forage production on Pennsylvania dairy farms. The model simulates crop production, feed use and the return of manure nutrients to the land. Forage losses and nutritive changes, the timing of field operations and the use of machinery, fuel and labor are among the many factors tracked by the model to predict performance and resource use for typical dairy farms. Simulations were done for 22 weather years using Harrisburg, Pennsylvania weather data. Silage production costs were compared to those of alfalfa harvested in large round bales or grazed in a well-managed rotational grazing system.

Two farms were modeled. The smaller farm included 100 cows plus 85 replacement heifers on 250 acres of owned land. Alfalfa was grown on 90 acres along with 160 acres of corn. The larger farm included 500 cows and 425 replacements on 450 acres of alfalfa and 750 acres of corn. Milk production was set at 22,000 lbs/cow. Facilities included bunker silos for storing alfalfa and corn silages, and a tower silo for high moisture corn. All alfalfa cuttings,

except the second cutting, on the small farm were harvested as wilted silage. The second cutting on this farm was harvested as dry hay in large round bales. Corn was harvested as silage and high moisture grain to fill the available silos, and additional corn was harvested as dry grain.

A third farm was simulated which was a variation of the 100-cow farm that included grazing. All parameters of the farm were the same except that land use was changed to 150 acres of alfalfa and 100 acres of corn. Of the total alfalfa, 50 acres were grazed in the spring, 85 acres in the summer and 150 acres in the fall after the third harvest. The remaining alfalfa was harvested with a three cutting harvest strategy using the same harvest methods and dates as used for the original 100-cow farm. Equipment costs included fence, watering equipment and pasture clipping. Because field machinery was used less, cost was depreciated over 50 percent more time or 15 years.

Results and Discussion

Average costs of forage production on the three farms is as follows. On the 100-cow farm, alfalfa silage was produced at an annual cost that varied over the 22-year simulation from $76 to $120/ton dry matter (DM) with a mean of $85/ton DM. The predominant cost was that of machinery, and the next largest cost was storage. Corn silage production was a little less costly, ranging from $60 to $ 124/ton DM with a mean of $74/ton DM. Machinery, energy and labor costs were less because mowing and raking operations were not required, and because the greater yield at harvest allowed equipment to be used more efficiently. Storage costs were a little lower for alfalfa because multiple cuttings allowed refilling of the silos, and thus more forage was stored in a structure.

Hay production costs on the 100-cow farm were near $100/ton DM with a range in annual values from $83 to $167/ton DM. Machinery costs were higher because the baler and bale handling equipment were used relatively little. Hay can be produced more cost effectively when machinery is used for three or more cuttings per year.

Grazing was by far the lowest cost method of producing forage with a production cost near $30/ton DM. Annual values over the 22-year simulation ranged from $26 to $42/ton DM. Although grazing costs were quite low, they were only a portion of the total economic picture. Dairy farms in the northern U.S. cannot rely solely on grazed forage, so a substantial amount of hay or silage must be produced or purchased for the winter months. Despite the low production cost, grazing can reduce the profit of a high producing dairy farm by increasing other feed costs and reducing milk production.

On the 500-cow farm, where all four cuttings of alfalfa were harvested as silage using a self-propelled chopper and dump trucks for transport, alfalfa silage production costs dropped to $60/ ton DM. The range in annual values was $55 to $82/ton DM. Machinery, labor and storage costs were all reduced by producing forage more efficiently in greater amounts. Corn silage production costs were only a little less ranging from $48 to $95/ton DM. Again, compared to alfalfa silage, machinery, energy and labor costs were less, and storage and cropping costs were greater.

Conclusion

Silage production costs decreased as farm size increased with alfalfa silage costing a little more to produce than corn silage. The major cost in silage production was that of machinery which included depreciation, repairs and maintenance, and the next major cost was that of the storage structure.

C.A. Rotz and T.M. Harrigan

USDA Dairy Forage Research Center

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Depending on time of removal, oat regrowth after chopping for oatlage can be significant. As a grass, oats would likely have an effect on forage quality in subsequent harvests. In the summer of 1996, we conducted a study to investigate the effects of this oat regrowth on forage quality and yield.

Two new seedings of oats/alfalfa were selected, one a UWRF LabFarm No. 1, and a second at UWRF Lab. Farm No. 2. These two farms are separated by about four miles. The Farm 2 site is a clay loam, and the Farm 1 site is a sandy loam. Oatlage was remove at the boot stage. The stand was sprayed with Poast Plus herbicide when oat regrowth was six to eight inches tall. Some unsprayed areas were left. Plots were harvested when the alfalfa was at the bud stage, and yield and quality parameters were determined.

Table 2 shows the oat density at the two sites. Farm 2 had the heavier regrowth, while Farm 1 had a light infestation. Percent by number is simply the percent of the total plants in a square foot that were oats. Percent by weight is the weight in a square foot that was oats.

 
 

Table 2. Oat Density at Each Site
% Oats	Farm 1	Farm 2
By Number	16	31
By Wet Weight	40	59
By Dry Weight	40	54

 

The impact of oat regrowth removal is shown in Table 3. Regrowth removal improved forage quality at both locations. Both crude protein and relative feed value were increased. The effect was greater at Farm 2 where the oat regrowth was more dense. Yields were similar between the sprayed and unsprayed plots at Farm 1. At Farm 2, the unsprayed plots yielded more due to the presence of greater oat regrowth. Milk per acre increased at both sites as a result of increased quality. This yielded a net return over cost of application ($10.00/acre) of $23.74 at Farm 1 and $29.62 at Farm 2.

This study represents one year’s data at two sites in River Falls, Wisconsin. Many factors may affect individual results including oat growth stage at cutting, weather conditions following cutting and Poast Plus application, fertility, stand density and weeds. A well fertilized, dense, weed-free stand will be most able to respond to the reduced competition from oats. This data suggests that removal of oat regrowth following harvesting of oatlage may be economically advantageous

The Value of Grass Control in Established Alfalfa

Grass weed infestations are all too common in alfalfa fields in Wisconsin. Grass weed infestations reduce alfalfa yield and lower forage quality. With the registration of the herbicides Poast and Poast Plus several years ago, grass control in alfalfa became much easier. The decision as to when to use this product is not always an easy one. Unlike corn and soybeans in which the benefits of weed control are obvious, the effects of weed control in forage is less so. Weed control may not improve total forage yield, but will, in most cases, improve the yield of the alfalfa component of the forage and improve quality as well. In summer of 1996, we took a closer look at the benefits associated with removing grass weeds from an established stand of alfalfa.

A two year old stand of alfalfa was chosen at the UWRF Laboratory Farm. At bud stage, alfalfa plants were hand clipped along with yellow foxtail plants which were also present in the field. Plants were dried and mixtures were made consisting of 0, 5, 10, 20, 30, 40 and 100% yellow foxtail. These samples were then ground and analyzed by NIRS. The study was replicated three times.

 
 

Table 4. Effect of Grass Weed Percentage on Forage Quality in Established Alfalfa
Percent Grass	CP	ADF	NDF	RFV	MILK/ACRE
0	19.9	29.3	40.8	150.8	1988
5	18.9	30.2	42.6	142.6	1868
10	18.6	31.6	44.3	134.9	1730
20	18.5	31.3	44.3	137.1	1743
30	16.6	32.5	48.1	123.0	1522
40	16.4	32.9	50.2	117.3	1411
50	14.3	34.1	52.7	112.0	1247
100	7.8	38.4	67.0	82.1	422

 

The results of this study are shown in Table 4. Pure alfalfa (0% Grass) measured 19.9% CP with a RFV of 150.8. There was a stepwise decline in quality with increasing grass percentages. Pure foxtail (100% Grass) contained 7.8% CP with a RFV of 82.1. Just 5% grass reduced CP by a point and caused RFV to decline 8.2 points.

One of the factors which is important in deciding to treat a grass infested stand is the amount of economic return for the cost of the herbicide application. There are two ways to determine this. The first is by putting a value on the forage harvested and then comparing that to the cost of the herbicide treatment. Value of forage at quality tested hay auctions varies with quality. A look at ten years of data from these auctions shows the value of hay at these auctions to be related to RFV in the following manner: $/Ton = 0.88(RFV) - 22.3. By inserting the RFV values in our experiment, we can determine a return/acre for the herbicide treatment. A second way to examine the return is by calculating milk per acre increases and assigning a dollar value to determine return. The results of both of these methods is shown in Table 5.

 
 

Table 5. Return on Poast Plus applications to Control Grass in Established Alfalfa.
Percent Grass	RFV	$/Ton	$ Return	Milk/Acre	$ Return
0	151	110	-	1988	-
5	143	103	7	1868	17
10	135	96	14	1730	36
20	137	98	12	1743	34
30	123	86	24	1522	65
40	117	81	29	1411	81
50	112	76	34	1247	104
100	82.1	-	-	-	-

 

The cost per acre for a Poast Plus application is around $10.00. In terms of $/Ton of hay sold, a Poast Plus application could be justified for any grass infestations above 5 percent. Returns increased dramatically at 30 percent or greater. Keep in mind, at these levels, yield decreases may well offset quality gains, particularly if the stand is thin and not able to take advantage of the reduced competition. Remember also, these returns are based on 10 year average alfalfa prices, returns in a given year will be greater or less depending on hay prices.

Returns based on increases in milk per acre were greater. An application could be justified at grass infestations as low as 5 percent. As grass percentage increased, returns increased. Yield in this case was held constant for comparison purposes. In fact, yields would decline if grass weeds were a significant part of the stand and the alfalfa was thin.

This data was taken from a single field from second cutting of a single year. Environmental factors, weed species and alfalfa variety are among several factors which could affect the results in a given year. This data is in agreement with other researchers including Jerry Doll at UW-Madison, and Dave Grafstrom of BASF who have shown that grass percentages as low as 10 percent may justify an application of an herbicide to remove them.

Dennis Cosgrove, UW-River Falls

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Last issue included a short article about Plateau herbicide for warm season grass establishment. After a few questions, I thought I would further clarify that article. At this time, Plateau herbicide is only labeled for weed control in roadside and other non-crop areas. This would include CRP acreage, but the product is not currently labeled for any crop usage. None the less, Plateau promises to be a benefit when establishing warm season grasses on these acres and for prairie restoration. We will have a small plot at Farm Progress Days in 1998, so come and see the product for yourself.

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Carl Thenius, our 1997 Spokesperson Contest winner, placed second at the American Forage and Grassland Council Annual Symposium in Ft. Worth Texas April 14. The meeting included formal presentations of forage research, farm and ranch tours in the Ft. Worth area, a hay show and many other activities associated with forages. As with our own annual meeting, the Spokesperson Contest is a popular event. Carl did an outstanding job of presenting Wisconsin agriculture in a positive light and was an excellent representative of Wisconsin dairying. Congratulations to Carl, and thank you once again to our spokesperson contest sponsors, Pioneer Hi-Bred International, Inc. and Cenex Land O’ Lakes for their support.

This year we have note unusually high levels of sclerotinia in several portions of Wisconsin. It appeared first this spring as dead plants (that many mistook for winter kill) with small hard, pea-sized of smaller ball at the base of the stems. The tap root, if cut open, would have an orangish color. During this season, plants will appear wilted when surrounding plants are not.

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REMINDER:

WISCONSIN FORAGE COUNCIL ANNUAL SYMPOSIUM IS JANUARY 27 AND 28, 1998 IN EAU CLAIRE, WISCONSIN. WE HOPE TO SEE YOU THERE!

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