Hay

• 1. Introduction

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  Hay is dried grass, legumes and other herbaceous plants, cut and cured so that cattle, horses, goats, sheep, rabbits and guinea pigs can eat what would otherwise have withered in the field months ago. Even pigs can eat hay, though they digest it less efficiently than true herbivores. Turning a green field into a safe, edible bale depends on a narrow window of good weather, a dependency old enough to have given rise to the idiom to make hay while the sun shines. Getting that window right has occupied farmers for millennia, from hand tools to today's mechanized balers. What actually happens between a cut stem of grass and a bale that keeps an animal fed through the winter?

• 2. What Goes Into Hay

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  Ryegrass, timothy, brome, fescue, Bermuda grass and orchard grass all show up in hay mixtures, with the exact blend depending on region. Legumes join the mix too, chiefly alfalfa, also called lucerne, and red, white and subterranean clover, best cut before they bloom. Other pasture forbs sometimes slip in as well, though some are toxic to certain animals and are not deliberately included. In the UK, some hay still comes from traditionally managed hay meadows, prized for their diverse flora and rich ecosystems; historically, the species-rich hay from these meadows was fed to horses. Oat, barley and wheat plants are occasionally cut green for hay, but more often become straw instead, the leftover stems and dead leaves baled after the grain has been harvested and threshed. Straw serves mainly as animal bedding, and although it can be used as a fiber source in fodder, it carries less nutrition than hay. Some agroforestry systems grow what is called tree hay. What actually determines hay's quality is its leaf and seed content, since those parts hold far more nutrition than the stems. Farmers try to cut when the seed heads are not quite ripe and the leaf growth is at its peak, then dry the cut material carefully so the leafy matter stays intact enough to be gathered by machinery without shattering.

• 3. Racing The Weather

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  Hay production, sometimes called haymaking or haying, moves through several steps: cutting, drying or curing, raking, processing and storing. Unlike grain crops, hayfields do not need reseeding every year, though regular fertilizing helps, and overseeding every few years improves yield. The whole process is highly sensitive to weather, especially during harvest. Drought stunts both seed and leaf growth, leaving hay heavy with dry, coarse, low-nutrition stems, while overly wet weather can spoil cut hay in the field before it is ever baled. Hay cut too wet can also rot or grow mold after baling, creating toxins that can sicken the animals that eat it. After harvest, hay must be stored somewhere dry, since mold and spoilage both cut its nutritional value and can make animals ill; a symbiotic fungus that sometimes grows in fescue is known to cause illness in horses and cattle. During the growing season, spring and early summer in temperate climates, grass grows quickly, and hay reaches peak nutritional value when its leaves are fully developed but seed or flower heads are just short of full maturity. Farmers generally have about a two-week window to cut at that ideal stage; cutting too early leaves the grass too moist to cure well, while cutting too late produces coarser, less valuable, less nutritious hay. Alfalfa hay follows a similar logic, best cut when plants reach maximum height and are budding or just starting to bloom, since cutting during or after full bloom lowers its nutritional value.

• 4. How Animals Eat It

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  Hay can supply as much as 100% of a grazing animal's diet, typically stepping in whenever winter, drought or other conditions make pasture unavailable, or when an animal is kept in a stable or barn. Most animals get hay in two daily feedings, morning and evening, mainly for human convenience, since grazing animals on pasture would naturally eat throughout the day. Animals raised for meat may be allowed to eat hay all day, while working animals that are ridden or driven often get a more limited ration to keep them from getting too fat, and in most cases hay or pasture forage still needs to make up at least 50% of the diet by weight. Cattle and sheep, as ruminants, digest hay differently than horses, which are nonruminant hindgut fermentors relying on a single-chambered stomach and a cecum. The four-chambered stomach of cattle lets them break down older forage and tolerate mold and dietary change better than horses can, whose more sensitive hindgut bacteria demand a more consistent quality of hay. Cattle eat large amounts at a single feeding, then take considerable time to digest it through rumination, often while lying down. Sheep eat between two and four percent of their body weight in dry feed per day, extracting maximum nutrition from just three to five pounds of hay daily, a process that takes three to four hours. Horses, by contrast, eat in small portions throughout the day and can process only about 2.5% of their body weight in feed within 24 hours; in the wild, they evolved to graze continuously while covering up to 50 miles, or 80 kilometers, a day. Low-quality hay can give horses an unhealthy, obese hay belly from empty calories, while a dramatic change in feed or moldy or toxic hay can make them sick; colic remains the leading cause of death among horses, and contaminated hay can also cause respiratory problems.

• 5. From Rome To The Reaper

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  Columella described the standard haying process of the early Roman Empire in his De re rustica: workers cut grass by scythe in teams, dried it in the field, and gathered it loose onto wagons. Horse-drawn mowers came later. Once cut and dried, hay was raked or rowed up by hand, with a fork or rake, or with a horse-drawn implement, before pitchforks piled it loose onto a cart, wagon, truck or tractor-drawn trailer, a job a sweep could also handle instead of forks. Loose hay traveled to a slightly elevated storage site chosen for good drainage, where builders constructed a haystack, a skilled task since the stack had to be made waterproof as it went up; the stack would then compress under its own weight and cure through heat released by residual moisture. Stacks typically sat inside a fenced rick yard, separate from the rest of the paddock, often thatched or sheeted against the weather, and a hay knife was used to cut off daily slices to feed animals. Some farms instead stored loose hay in a barrack, shed or barn, or in the upper storey of a cow-shed or stable, with hatches in the floor to drop hay down into racks below; depending on the region, the term hay rick could describe the cutting machine, the haystack itself, or the wagon used to gather the hay. Mechanization changed everything: most hay production had become mechanized by the 1930s, led by the tractor and the baler, though the first hay press appeared around 1850. Timothy grass and clover, both originally from Europe, were the most commonly used hay plants in the early 20th century United States. Baling made hay easier to handle and cheaper to store and ship; the first bales weighed about 300 pounds and came from vertical presses using a horse-driven screw mechanism or a dropped weight. HL Emery patented a horse-powered, screw-operated hay press in 1853, while other machines were reported as early as 1843, built by PK Dederick's Sons of Albany, New York, or by Samuel Hewitt of Switzerland County, Indiana. Horizontal machines followed, including PK Dederick's own Perpetual Press of 1872; by about 1882 steam engines could power them, and the continuous hay baler arrived in 1914. Mobile balers, which gathered and baled hay in a single pass, appeared around 1940, producing rectangular bales light enough, at 70 to 100 pounds, or 32 to 45 kilograms, for one person to lift and stack by hand. Later in the 20th century, balers arrived that could produce large bales weighing up to 3000 lb, setting up the large-bale era still to come.

• 6. Modern Haymaking

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  Terminology and methods for making hay vary by region and have shifted throughout history, but the core steps remain: tall grass or legumes are cut at the right stage of maturity, dried by the sun, then raked into long, narrow piles called windrows. Modern swathers can rake hay into rows as they cut it, turning it periodically to dry, while older methods leave cut hay spread across the field until dry before raking it into rows. Turning the drying hay, often with a hay rake or a tedder, speeds the process, especially if rain interrupts it, though turning too often or too roughly knocks leaf matter loose and reduces the hay's nutrition. Hay conditioners and chemical desiccants can speed drying further, but these methods cost more and are mainly used where modern technology, high hay prices and excess rain all combine. Once cured, hay is gathered into bales or bundles and hauled to storage, though in some regions it is still stacked loose without baling. Small operations often pull a single tractor through separate mowing and raking passes, while larger operations use a swather to cut and windrow hay in one step; balers, usually pulled by a tractor, need more powerful tractors as bale size grows. Conditioning the crop during or soon after cutting, by using rollers or flails inside a mower conditioner to crimp, crack or strip the stems, is now common, since it shortens drying time, particularly in humid climates.

• 7. Fertilizer And New Hazards

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  Modern hay production leans on artificial fertilizer and herbicides, even as manure remains a traditional option. Hay certified weed-free for use in wilderness areas is often sprayed with chemical herbicides, and even some non-certified hayfields are sprayed to limit noxious weeds. Hay destined for animals whose meat will be certified organic requires organic fertilization and weed control instead, relying on compost, field rotation and regular mowing during the growth phase to keep weeds down. Some producers have experimented with human sewage sludge to grow hay, a method that is not certified organic and carries no mandated EPA warning label; hay grown this way can take up heavy metals that pass on to the animals that eat it. Molybdenum poisoning is a particular risk for ruminants like cows and goats grown on such hay, and it has caused animal deaths. A herbicide called aminopyralid poses a different problem: it can pass through an animal's digestive tract intact, making the resulting manure toxic to many plants and useless as fertilizer for food crops, and it can persist in the environment for several years.

• 8. Bales, Stacks And Danger

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  Small square bales come in two main styles: the smaller two-tie bale, held by two twines, and the larger three-tie bale, held by three. Two-tie bales, the original form factor, remain popular in the hobby animal market for their convenient size, while three-tie bales suit exporters and buyers chasing a better price per ton; hay-bucking competitions built around the small bale still draw crowds at rodeos and county fairs. Because rain washes nutrition out of hay and small square bales are especially vulnerable, they are usually kept in a haymow or hayshed, or under tarpaulins if stacked outside; round bales resist spoilage better thanks to their shape and tighter compaction, and net wrap adds further weather resistance. Large square bales can weigh up to 1000 kilograms, while large round bales typically weigh 300 to 400 kilograms and pack hay more densely at the center; dry-area farmers can often leave these outside, while those facing heavy snowfall stack them under a shed or wrap them in plastic that still lets the hay breathe. A bale wrapper can seal a round bale completely to trigger fermentation for silage, a cheaper alternative to a silo that is common in very damp climates and known in Europe as haylage; any tear in the plastic lets in oxygen and ruins the fermentation. Traditional outdoor haystacks relied on loose hay, with the weathered top layer sacrificed to the following summer's compost heap, and building a stack that shed rainwater well was a skilled task, sometimes finished with a thatched top. After World War II, a shortage of British farm laborers skilled in thatching haystacks helped push the industry toward large bales instead, and by the 1960s many farmers stored hay outdoors in large bales whose own outer surface shed the weather. Some structures, called a Dutch roof, hay barrack or hay cap, used a moveable roof on four posts to protect a stack, and building tall haystacks was sometimes aided by a ramp called a beaverslide. Hay ranks among the safest feeds available to grazing herbivores, but spoiled hay can sicken animals with coughs, mold-related illness, or even botulism, if a small animal like a rodent is killed by baling equipment and rots inside the bale. An endophytic fungus that sometimes grows on fescue can cause abortion in pregnant mares, and Pimelea, a native Australian plant also called flax weed, is highly toxic to cattle. People who work around hay dust risk Farmer's lung, a hypersensitivity pneumonitis, or allergic rhinitis from airborne allergens. Hay baled before it fully dries can generate enough heat through bacterial fermentation to catch fire; the risk lasts until moisture drops below 40%, and hay is considered fully dry at 20% moisture, with most combustion problems striking within five to seven days of baling. A bale under 120 F is generally safe, one between 120 and 140 F needs to be pulled from a barn and separated to cool, and one above 140 F can combust outright. Weight brings its own dangers: large round bales can weigh over 1000 pounds and cannot be moved without special equipment, and because they are cylindrical they can roll off stacks or equipment. Between 1992 and 1998-74 farm workers in the United States died in accidents involving large round hay bales, most while the bales were being moved from one place to another.