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Alfalfa production budgets show that equipment costs (purchase, operating, and maintenance) account for about 40 percent of the cost of hay production. Many aspects of haying has to do with equipment. AGMACH$ is a software that addresses many of the details and cost tradeoffs for various types of equipment. Alfalfa yield and quality are highest at the moment of harvest. In other words, yield of a particular cutting cannot increase after it is harvested. In fact, respiration continues for sometime after harvest, thereby decreasing total dry matter. Nothing can be done to improve alfalfa quality after it is cut; however, many factors begin at the moment of harvest to reduce forage nutritive value. By not harvesting alfalfa effectively or allowing the hay to "weather," forage quality is reduced and marketability is impaired significantly. Alfalfa can be harvested using several different methods for diverse purposes. It can be harvested and utilized fresh as green manure, green chopping, or grazing. In these cases, moisture concentration usually ranges from over 80 percent to 65 percent, and dry matter losses are insignificant. When harvested as silage alfalfa, haylage, or baleage, moisture ranges from 60 percent to 50 percent, and quality can be maintained with little harvest loss. In Oklahoma, alfalfa is usually harvested and stored as baled hay with moisture concentrations less than about 20 percent. Dry matter losses in harvesting, handling, and storing dry alfalfa can range from as little as 10 percent to over 30 percent. Quality losses often accompany dry matter losses. The rest of this section is devoted to methods of harvesting alfalfa as hay with an emphasis on minimizing yield and quality losses. A critical factor to consider is that harvesting, handling, and storage can represent over 40 percent of the total cost of alfalfa hay production. These inputs can mean the difference between profit and financial failure due to the magnitude of investments. Profitable production and marketing high-quality forage requires proper harvesting, handling, and storage. Buyers are often willing to pay a premium for high-quality hay. Based on several years of Oklahoma HAYMARKET data, buyers paid an average of over $2.40 per ton more for each percentage point increase in protein.
Cutting and conditioning are the first of several critical steps to ensure high-value hay. Hay quality is directly related to leaf retention because leaves contain a higher proportion of crude protein and energy than stems. A growing alfalfa plant contains approximately 80 percent water. When the plant is cut, it continues to respire or "breathe" until water content is reduced to about 40 percent. Below 40 percent, leaves dry at a much faster rate than stems because leaves are thin and have a relatively large ratio of surface area to mass in comparison to stems. Because of the cell structure and surface wax layer of stems, drying occurs slowly. By the time stems reach proper moisture content for baling, leaves may be too dry and may shatter easily. The relatively simple subject of cutting alfalfa includes the consideration of many different pieces of equipment. Each piece of harvesting equipment has certain advantages and certain disadvantages. Before arbitrarily purchasing harvesting equipment, producers should consider sickle bar mower, mower-conditioner, rotary disk mower, disk mower, conditioner, pull-type windrower, self-propelled windrower, etc.
Raking Raking is used to enhance uniform drying. The most common type of rake rolls and fluffs the windrow, bringing the bottom layer to the top. The rolling action exposes more of the stems while protecting the leafy portion of the plant. Hay should be raked when the moisture content is above 30 percent to minimize leaf shatter. Raking during the early morning or late evening after the leaves absorb moisture from the air can further reduce leaf loss. Dry matter losses can range as high as 15 percent if alfalfa is raked when it is too dry. Some raking options include side delivery rake, twin side delivery rake, wheel rake, twin wheel rake, windrow inverter, etc. Each tool has certain strong points.
To avoid severe storage losses from excessive heating and molding, alfalfa should be baled at no higher than about 20 percent moisture. Alfalfa can be baled and stored successfully, however, at higher moisture contents by using preservatives. Depending on the type of preservative, hay can be baled at moisture contents as high as 35 percent. Baling at higher moisture content reduces the time hay is exposed to weather and decreases dry matter loss because there is less leaf shatter. Minimizing leaf loss can also mean a higher crude protein content. Optimum moisture content for baling depends on bale size. For small rectangular bales, the moisture content should be no higher than about 20 percent without preservatives. The upper limit for large bales, both rectangular and round, is about 16 percent to avoid taking special precautions to prevent excessive heating. If large round bales are stored outside and unprotected, moisture content at baling can be increased to about 20 percent. Without the aid of an electronic moisture meter, experienced hay producers often rely on two rule-of-thumb methods for determining when alfalfa hay is dry enough to bale. One method is to take a handful of hay from the underside of the windrow and twist it. If there is no free moisture present and the stems are brittle, the hay should be in good condition for baling. If the hay is very dry and brittle, it is probably too dry to bale. When the stems appear too dry, allow the leaves to absorb moisture form the air during late evening or early morning before baling, a process often called "casing-up." Scraping the epidermis or outside layer of the stem is another method used to determine when to bale. If the stem epidermis can be peeled off, the hay is too wet. If the epidermis doesn't peel away, the hay is dry enough to bale. An electronic forage moisture meter can be a useful tool for determining proper moisture content at baling. These may be used in the windrow but are more reliable when the hay is baled. Probe from the end of rectangular bales and through the diameter of round bales. Take at least five probes of each bale and average the readings. Probe several bales to account for field variations. If the readings vary by more than three percentage points, take several more probes and recalculate the average. There are many factors that affect the accuracy of a moisture meter. Two factors are bale density and the use of chemical conditioners. Probing bales that are very "tight" may yield readings over two points higher than the actual moisture content. Some preservatives, such as propionic acid, can increase readings as much as four percentage points. If preservatives are used and the instruction manual for the meter does not provide information on the effects of chemicals on performance, contact the manufacturer of the meter for additional information.
Small Rectangular Bales were the most common bale type for alfalfa in Oklahoma for many years. The most popular size for these "square" bales was 14 x 18 by 36 inches long, weighing between 70 and 80 pounds, depending on moisture content. Normal baling rates range from 5-10 tons per hour. In good baling conditions (heavy windrows and high moisture content), leaf loss at the pickup and in the bale chamber should be less than four percent. Bale chamber losses may exceed five percent with overly dry alfalfa. Large Rectangular Bales are the preferred bale type for many dairies. Bale size ranges from about 2 x 2 x 8 feet long (mid-size), weighing about 750 pounds to 4 x 4 by 8 feet long (large), weighing about 2000 pounds. Normal baling rates range from 15 to over 25 tons per hour. In some cases, smoothness of the field dictates ground speed. Dry matter losses during baling are comparable to small rectangular balers. A major disadvantage of large square bales is baler cost, which can be more than three times the cost for small square or large round balers. Large round bales were introduced in to Oklahoma in the early 1970s. The popularity of these bales can be attributed to low labor demand. Common bale sizes range from four feet diameter by four feet long, weighing about 600 pounds, to six feet diameter by six feet long, weighing about 2000 pounds. Normal baling rates range from 8-16 tons per hour. Most large, round balers are comparable in price to small rectangular balers. In overly dry hay, alfalfa leaf loss can be as high as 10 percent at the pickup and 25 percent in the baling chamber. Under optimum conditions, total losses can be held to about five percent. Using high feed rates that reduce the time a bale is being formed can minimize bale chamber losses.
Mechanical Conditioning The most common method of enhancing stem drying is mechanical conditioning. Conditioners use a set of intermeshing, counter-rotating rollers that crush, bend or break stems, allowing moisture to escape easily. If the stem dries faster, the hay can be baled sooner, which reduces the time hay is exposed to the weather. Conditioners also result in reduced leaf shatter during raking and baling because the leaves tend to dry at about the same rate as stems. Proper roller clearance adjustment is important. Roller spacing used for the thick stems at first cut are often inadequate for the fine stems in subsequent cuttings. It should be noted that mechanical conditioning is not recommended if blister beetles are present. (See "Insect Management" in Chapter 2, for details)
Hay additives can reduce field curing time and decrease losses during baling. However, before investing in equipment and chemicals, be sure to consider the additional time, labor, and cost that will be required. Chemicals should never be use as a substitute for good management practices. Chemicals available to help condition hay include two major groups -- drying agents and inhibitors. They work in different ways. Drying agents normally contain potassium carbonate or sodium carbonate, which are alfalfa salts. These chemicals change the water-transmitting properties of the surface wax layer allowing moisture to escape readily. Studies show that total drying time can be cut by as much as 24 hours, with the average being about 12 hours. In Oklahoma, the greatest potential for profitable use of drying agents is during periods of poor drying conditions consisting of low temperature and high humidity, common during the first cutting. However, some studies show the difference in drying times between treated and untreated alfalfa for the first cutting may be small because of the high volume of forage and the possibility of wet ground, which retards drying. When using chemical conditioning, the shields on mower-conditioners should be adjusted to lay the hay on the ground in a thin layer covering the full swath width. Drying agents are more effective when the hay is dried in a thin mat. Depending on the type of drying agent and recommended application rate, chemical conditioning can cost from $3 to over $8 per ton of treated hay. In addition, the cost for applicator parts and equipment can range from $700 to over $1,200. The additional labor demand can also be a factor. Mixing and handling water and chemicals can increase total mowing time as much as 20 percent. Inhibitors help avoid severe storage losses from excessive heating and molding when alfalfa is baled at moisture contents higher than 20 percent. Depending on the type of preservative, hay can be baled with moisture content as high as 35 percent. Baling at higher moisture content reduces the time hay is exposed to weather and decreases dry matter loss because there is less leaf shatter. Minimizing leaf loss can also mean a higher crude protein content. The three most commonly used inhibitors are organic acids, ammonia, and inoculants. Organic acids, such as propionic acid, can be used for treating hay up to about 35 percent moisture content. It is sprayed onto the hay as it enters the baler. Uniform coverage is very important. Organic acids inhibit mold growth and enhance bacterial growth. One of the major drawbacks to using the original acid was the corrosive effect on equipment. Buffered propionic acid is now commonly used to avoid corrosion problems. Another potential problem is odor. The acid vapors can be annoying, especially in poorly ventilated storage. Preserving alfalfa with organic acids can be expensive. Equipment and chemical costs can range from $8 to over $12 per ton. Ammonia, another mold inhibitor, is usually applied to baled hay after it is placed in storage. Bales with up to 30 percent moisture content are stacked and covered with polyethylene. Anhydrous ammonia is released under the cover at a rate of about two percent of hay weight. The stack is sealed for at least two weeks. Ammonia inhibits both mold growth and bacterial growth. In addition, the nitrogen content of ammonia will result in a small increase in the crude protein content of the hay. Equipment and chemical costs for using anhydrous ammonia as a preservative range from $5 to about $8 per ton of hay. The major disadvantage of anhydrous ammonia is human and animal safety. For humans, strong concentrations can cause severe burns, blindness, and death. When applied to moist hay, ammonia combines with the moisture in the hay and becomes relatively harmless. However, vapors from treated bales can be irritating, especially in poorly ventilated areas. It has been reported that ammonia treated forages have caused toxic reactions in animals. Symptoms of the toxicity include hyper-excitability, circling, convulsions, and death. Newborn calves that are nursing from cows fed these forages are also susceptible to the toxicity. It is important that anhydrous ammonia be used with care and applied at the recommended rate. If signs of toxicity occur, the feeding of treated alfalfa should be discontinued.
Inoculants usually consist of bacteria or enzymes that creates an environment in the bale that stops growth of hay-rotting bacteria and molds. They are applied to hay as it enters the baler, usually as a dry product. It appears that inoculants can be effective at moisture contents as high as 25 percent. Once in the bale, inoculants work somewhat like preservatives. Inoculants are probably the most economical means of preservation because little is invested and little can be lost. If it saves some hay from molding and prevents a barn from burning, inoculants are worth the money. Equipment and chemical costs can range from as low as $2 to over $5 per ton.
Most alfalfa hay in square bales (small and large) is placed in covered storage. Commercial hay producers prefer enclosed barns to retain color and minimize storage losses. Under-roof storage with one or more sides open is also popular, especially for round bales. Open sides are usually away from prevailing winds. Hay is stacked tight along open sides and at the top to prevent rain and snow from blowing into the building. Barns and under-roof storage should be located on a well-drained site and as close to feeding areas as possible. Dry matter losses in enclosed barns are usually less than two percent during the first nine months in storage, while losses in under-roof storage can be as high as five percent (Table 6-2). Losses in forage quality, such as crude protein and fiber, are negligible. The major drawback to barns and under-roof buildings is cost. Initial cost of construction can range from about $2 to over $6 per square foot. Building payback time could take over 10 years, depending on the cost of the structure and hay prices. Because of their shape and ability to shed precipitation, large round bales are often stored outside and unprotected. Research shows, however, that dry matter losses can reach 25 percent, depending on bale quality and storage conditions (Table 6-2). Serious deterioration is usually confined to the outside f4-8 inches of the bale. However, in a five-foot-diameter bale, the outer eight inches represent about half of the bale's volume. The depth or thickness of weathering depends on many factors including the amount of rainfall during the storage period, condition of alfalfa when baled, bale shape, and density.
If bales are stored outside and unprotected, there are several guidelines that should be followed to minimize hay loss.
Covering bales with plastic or tarps is another storage option, especially for round bales. However, dry matter losses can range as high as 10 percent for alfalfa stored up to nine months under a cover on the ground, depending on weather, soil conditions, and bale density. Avoiding ground contact by setting the bales on pallets, racks, fence posts, or railroad ties can save over five percent in dry matter losses. Cost of hay covers, not including labor, can range from less than $2 to over $7 per ton, depending on the type of cover and the size of stack. Covers often require continual attention for repairing tears and re-securing tie-downs, especially during periods of high winds.
Bale handling and transportation are important factors when choosing bale type. For small square bales, the most common field-handling method consists of a pop-up loader attached to a flat-bed truck. Bales are taken to storage or loaded onto a semi-trailer for shipping. Field loading rate is about 1.5 tons per man-hour. At least two persons are needed for loading. Because custom haulers and locally hired laborers became so difficult to employ, alfalfa producers with large acreages have changed to using automatic bale wagon systems. An automatic bale wagon with one operator can replace a three-man crew. High labor requirements and increasing costs of hand hauling have caused some commercial growers to abandon their small square bale operation for large bale package such as large rectangular bales. Large rectangular bales are loaded onto flat-bed trucks or semi-trailers directly in the field at about 20 tons per man-hour. Commercial haulers prefer large square bales to small square bales because they can drive into a field and be loaded for a cross-country trip in less than an hour. Transportation can be a major problem with large round bales. Interstate hauling regulations limit load widths to 8.5 feet. In Oklahoma, commercial hay haulers are allowed to transport a load of round bales up to 11 feet in width, during daylight hours only, after securing a special oversize-load permit.
Avoiding Hay Fires Spring and early summer cuttings often present the greatest risks for hay fires because of the difficulties of drying hay before baling. No matter the time of year, if rain is in the forecast, hay producers are often tempted to bale at a little higher moisture content to avoid weather damage. If hay is baled too wet and packed too tightly into storage, severe heating can occur causing significant dry matter and quality losses or worse - a hay fire. Heating results from plant respiration and microbial activity. It can occur in baled hay at moisture contents as low as about 13 percent. Therefore, heating is a natural occurrence with temperatures reaching over 120°F even in hay baled at safe moisture contents. If excess moisture is present, heat-resistant fungi become active which can drive the temperature to over 150°F. Above about 170°F, the microorganism's die, but heat-producing chemical reactions continue to drive temperatures up. Between 450° and 550°F, spontaneous combustion can occur if the material is exposed to air. Hay fires can occur over two weeks after the hay is placed into storage. Generally, temperatures below 140°F indicate no particular heating problem. Check the hay daily to see if temperatures continue to rise. Temperature readings between 140° and 170°F provide no clear indication of pending problems. Check the temperature every few hours to monitor changes. If the temperature is above 180°F, call the fire department. DO NOT MOVE THE HAY UNTIL THE FIRE DEPARTMENT IS PRESENT. When smoldering hay is exposed to air, it can undergo spontaneous combustion. It is imperative that the fire department be present before you attempt to move any hay with a temperature above 180°F. If it is not possible to measure temperature with an instrument, use a long steel rod as a probe. Drive the rod into the inner stack and leave it for at least 15 minutes. If the rod is too hot to handle, the temperature inside the stack is probably above 120°F and caution is warranted. Never stand on top of a stack you suspect may be heating because smoldering hay can create a cavity or pocket that often cannot be detected from the top of the stack. Preventing hay fires begins at the time the hay is baled. Optimum moisture content for baling depends on bale size. For small square bales, the moisture content should be no more than about 20 percent without preservatives. During warm, moist air conditions, reduce the moisture content when baling small squares to 18 percent. The upper limit for large packages, including round bales, is about 16 percent to avoid taking special precautions to prevent excessive heating. Round bale moisture content can be increased to about 20 percent if bales are stored outside and unprotected. Bale density also affects heating. The denser the package, the greater the resistance for heat to move through the hay. For round bales, consider reducing the bale diameter if baling wet hay. If you have a fixed-chamber baler, consider not wrapping the outer layer as tightly as usual to reduce bale density. If you bale wet hay, it is a good practice to leave round bales outside for at least a week before putting them into barn storage. If you must place bales immediately into the barn, stack bales loosely to allow plenty of air circulation. For large packages, arrange the bales loosely in a single layer for at least two weeks before stacking tightly. Granted, this takes more time and labor, but the risk of a fire is greatly reduced. |
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Alfalfa Production Guide for
the Southern Great Plains, 2001
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