Quick answer: Broiler litter averages roughly 63 lb N, 55 lb P₂O₅ and 47 lb K₂O per ton, but only about half the nitrogen is available the year you apply it — and University of Georgia research found very little carries over to year two, which contradicts the common belief that litter keeps working for years. Typical rates run 1–2 tons/acre on cool-season hay and up to about 4 tons/acre on bermudagrass. The real constraints are not nitrogen: they are phosphorus buildup (litter is nearly 1:1 N:P while grass needs 3–4:1), and contamination of the bale. Apply to actively growing forage right after a cutting, or in fall after the last cutting, give it rain to wash in, and raise your rake and tedder — dragging litter or soil into the windrow is how manure ends up in the hay.
Fertilizer prices make manure look free. It isn't, and the growers who have hauled it longest are the quickest to say so. But applied with some care it is a genuinely good fertilizer for hay ground, and it does things granular fertilizer does not — it builds organic matter, it releases slowly across the season, and it buffers soil pH.
This guide covers what is actually in poultry litter and other manures, what rate to use on hay ground, when to apply it between cuttings, and the part that gets skipped everywhere else: what happens when litter and manure end up in the bale rather than in the soil.
What is actually in a ton of litter
Poultry litter behaves like a complete fertilizer — it carries primary, secondary and micronutrients. University of Georgia gives its fertilizer equivalent as roughly 3-2-2, with these averages:
| Per ton | Broiler litter | Stockpiled | Cake |
|---|---|---|---|
| Nitrogen | 63 lb | 55 lb | 47 lb |
| P₂O₅ | 55 lb | 57 lb | 59 lb |
| K₂O | 47 lb | 47 lb | 46 lb |
| Calcium | 43 lb | 36 lb | 54 lb |
Source: UGA Extension B1330, Poultry Litter Application on Pastures and Hayfields.
Growers have used a rough "50-50-50" rule of thumb for years, and as the table shows that is not a bad first approximation. But averages are exactly the wrong thing to fertilize with. NC State Extension is emphatic: nutrient composition varies with bird type and life stage, feed ration, the proportion of bedding to droppings, the handling system, and whether you are getting whole-house cleanout or cake, so all litters should be sampled and analyzed before land application.
Sampling matters as much as testing. Litter is not uniform inside a house — the material around waterers, feeders and brooders differs from the rest. Take 10 to 12 subsamples from across the house (or from around a stockpile, at least 18 inches deep), mix them thoroughly in a clean bucket, and submit about a pint. Most state agriculture department labs run waste analysis for a nominal fee.
Litter also differs by bird. One producer explained the differences from the barn side better than most publications do — broilers are raised on an open floor and walk the litter down, layers are caged over a pit so their litter stays wetter and picks up broken eggs (and therefore calcium), and turkeys get the richest ration and produce the highest-nitrogen litter. That is why "a ton" of one is not a ton of another, and why yardage and tonnage do not convert cleanly.
The nitrogen half-life, and a myth worth correcting
This is the most consequential misunderstanding in the whole topic. A widely held belief among growers is that litter's advantage over commercial fertilizer is that it keeps giving:
"chicken litter last a lot longer than chem as it keeps going in to the soil year after year."
— hay king · HayTalk thread 14450
The research does not support the residual part. About 89% of the nitrogen in poultry litter is organic and must be mineralized by soil microbes before plants can use it; roughly 9% is ammonium and 2% nitrate, and those are immediately available. UGA's conclusion is that only about 50% of the nitrogen in a ton of litter is available during the growing season it is applied, and that most of the rest is either lost to the environment or locked into soil organic matter — so very little carryover should be expected the second year. NC State works the same arithmetic with an availability coefficient of 0.5 for broadcast application: 1 ton of broiler litter delivers roughly 29 lb of plant-available nitrogen per acre.
What growers are actually observing is real, but it is not stored nitrogen. It is the slow, steady mineralization within the season, which spreads nitrogen availability more evenly across the summer than a single granular application does — plus genuine improvements in organic matter, soil pH and potassium and phosphorus levels that persist for years. Those are worth paying for. Just do not budget next year's nitrogen against this year's litter.
Nitrogen is also easy to lose at application. Surface-applied ammonium volatilizes, and hot, dry, windy conditions can take nearly all of it. Applying ahead of a modest rain washes it in; applying ahead of a big storm sends nutrients down the ditch instead.
The phosphorus problem — the real limit on rate
Grasses need roughly three to four times more nitrogen than phosphorus. Poultry litter contains almost equal amounts of both. That mismatch is the whole ballgame: if you apply enough litter to meet your nitrogen needs, you are over-applying phosphorus every single year, and it accumulates.
A Texas grower ran the numbers himself on a forum in 2011 and landed exactly where the extension publications do:
"In theory that is enough Nitrogen & Potash for 2 tons of hay, but enough phosphate for over 8 tons of hay."
— hay wilson in TX · HayTalk thread 14450
UGA's field data shows the buildup plainly: after four years of litter on bermudagrass test plots in northwest Georgia, soil test phosphorus at 4 tons/acre was roughly 90 lb/acre and at 8 tons/acre roughly 165 lb/acre, against 50 lb/acre in the control. High soil phosphorus is directly linked to surface water quality problems, and in many states it is what triggers regulatory limits on your application rate.
There is one piece of good news specific to hay: phosphorus builds far more slowly on hayfields than on pastures, because you are hauling nutrients off in the bales. On grazed ground, roughly 80% of the phosphorus a cow eats goes straight back on the field. Hay production is the one system where litter is genuinely being drawn down.
Two standard mitigations, both worth knowing:
- Alternate litter years with commercial nitrogen years.
- Apply litter to meet the phosphorus requirement and top up nitrogen with commercial fertilizer.
Either way, soil test annually. See our guide to fertilizing hay fields for how to fold the manure credit into a full fertility program.
Copper, zinc and the long game
Litter carries copper and zinc — around 319 and 265 ppm respectively in UGA's broiler litter figures — and both accumulate after four to five years of repeated application. UGA found forage copper and zinc levels stayed within the recommended range for cattle nutrition even at 4 tons/acre for four years, so this is a soil management issue rather than an immediate feed safety one. But NC State warns that in fields with long-term repeated application these can reach levels causing severe plant toxicity, so it belongs on your annual soil test.
Rates and the catch nobody mentions about hayfields
Rates vary by forage and region, but the common working figures are:
| Situation | Typical rate | Notes |
|---|---|---|
| Bermudagrass hay | up to ~4 tons/ac | UGA's recommended rate in its northwest Georgia work. Often split across the season. |
| Cool-season grass hay | 1–2 tons/ac/yr | Many nutrient management plans cap at 2 tons/ac/yr. |
| Alfalfa or alfalfa-grass mix | light, for P and K | Legumes fix their own nitrogen. Value here is phosphorus, potassium and lime effect. |
One grower under a formal nutrient management plan described how he settled his program, and his reasoning covers timing, rate and contamination in three sentences:
"My nutrient management plan limits application rates to 2 ton per acre or less per year. I have found fall application solves a lot of time management and ground moisture issues. No feathers in the bales, neighbors have their windows closed and there are no ruts in the fields."
— SVFHAY · HayTalk thread 14450
"No feathers in the bales." That is the whole contamination problem stated in four words, and fall application after the last cutting is the cleanest answer to it — the material has all winter to break down and wash in, the ground is more likely to carry equipment without rutting, and you are not spreading upwind of neighbors in July.
The hayfield catch
Here is a finding that rarely escapes the research literature, and it matters if you are replacing fertilizer with litter on hay ground. In northeast Georgia work, grazed bermudagrass fertilized with poultry litter matched the productivity of inorganic fertilizer even though the litter supplied about 30% less nitrogen — 138 lb/ac against 200 lb/ac. In a hayfield, the same lower nitrogen rate produced a 22% reduction in yield.
In other words, the frequently repeated claim that litter performs as well as commercial fertilizer is best documented under grazing, where nutrient cycling makes up the difference. Under hay removal, you are exporting everything, and a nitrogen shortfall shows up directly in the tonnage. If you are swapping litter for fertilizer on hay ground, match the available nitrogen rate, not the total.
What ends up in the bale
This is the section that separates manure on row-crop ground from manure on hay ground. On corn ground, anything that does not dissolve into the soil is a cosmetic problem. On hay ground, it goes into a bale and then into an animal.
The mechanism is mechanical, and one grower described it precisely — including how he learned it:
"when spreading any type of chicken litter, cow manure, horse manure, etc., you really have to watch how you tedd your hay and how you rake your hay. Tedders set too low will throw clumps of manure into the hay and especially a ground driven rake - ie. a wheel rake will throw or flick manure particles off the top of the ground into the windrow of hay (ask me how I know) and animals will prefer another hay."
— Production Acres · HayTalk thread 12580
Note that this is not a niche opinion. University of Connecticut Extension gives hay producers the same instruction from the animal health side: when raking hay, raise the tines so they do not pull soil into the hay. A ground-driven wheel rake set to dethatch is the single most effective tool ever built for getting dirt and manure into a windrow. Set your rake to comb the top of the stubble, not scratch the ground. Our rake selection guide and merger vs rake vs inverter comparison cover which implements are gentlest on this, and the tedder guide covers setting depth.
Botulism: the risk that justifies the caution
The reason this matters more than "animals will prefer another hay" is that contaminated forage can be lethal. One grower reported the outcome on a client's farm:
"Word of Caution guys. I had an Amish client spread turkey litter on a hayfield last spring. Did not get enough rain to fully incorporate, mowed with disc bine, raked with wheel rake and litter had some decomposing turkey parts in it. Long story short, hay ended up with BOTULISM in it and Amishmen ended up with TEN DEAD HORSES. Just be careful."
— haybaler101 · HayTalk thread 14450
That account is consistent with the veterinary literature. Clostridium botulinum type C is associated with feed containing a decomposed carcass, and is found in poultry and poultry manures. UConn Extension lists use of poultry manure on land intended for horse hay as a risk factor, alongside baling above 22% moisture and baling small carcasses into hay. Horses are extremely sensitive, treatment is expensive and often unsuccessful, and a vaccine exists but covers only type B.
The practical takeaways are narrow and manageable:
- Do not spread litter that visibly contains carcasses or composted mortality. Ask your supplier.
- Give litter time and rain to break down and wash in before you cut — the failure above began with "did not get enough rain to fully incorporate."
- If your hay goes to horses, be conservative. Many horse-hay producers simply do not use poultry litter, and that is a defensible commercial decision as much as an agronomic one. Fall-only application on ground that will not be cut for months is the middle path.
- Bale dry and store dry. See baling moisture for net-wrapped bales and is moldy hay safe to feed.
Weed seed, ash and equipment
Manure that has not been composted hot enough carries viable weed seed onto clean ground — a recurring complaint in these discussions and a reason to prefer well-composted material or heat-treated products. Soil and manure flicked into the windrow also raise the ash content of the hay, which dilutes energy in every bale you sell, and abrasive material is hard on baler components.
Litter is also brutally hard on steel. Two growers put it plainly — one noting it is "very hard on any metal if not cleaned off, worse than salt," and another closing his advice with a postscript:
"p.s when your done spreading wash every thing off or your spreader and tractor will turn to rust"
— hay king · HayTalk thread 14450
Timing: between cuttings, or after the last one
Manure should go on an actively growing crop. NC State's guidance is to apply within 30 days of planting or within 30 days of breaking dormancy, and to minimize the delay between application and crop uptake so nitrogen is used rather than leached.
For a hayfield that means two sensible windows:
- Immediately after a cutting. The bales are off, the stubble is short so material reaches the soil rather than lodging in the canopy, and regrowth will start using the nitrogen within days. You get the longest possible interval before the next cut for it to wash in and break down.
- After the last cutting in fall. The option most experienced growers settle on. Whole winter to break down, no odor complaints during hay season, no rutting, and — the point that matters most here — nothing left on the surface to be raked into a windrow next June.
Whichever you choose, uniformity matters more than people expect. Calibrate your spreader and pay attention to swath spacing; uneven application creates nutrient imbalances across the field that show up as uneven regrowth and uneven quality in the bale.
Wheel traffic is a real cost on alfalfa, which is easily damaged by driving on regrowth. Grass tolerates traffic much better, which is one of the underrated reasons to run an alfalfa-grass mix if you plan to haul manure across the field several times a year.
Horse and cattle manure: the sawdust question
Horse manure is a different problem from poultry litter, and the difference is bedding. Stall waste is often more shavings than manure, and growers disagree sharply about what that does to soil. One position:
"Does your manure have sawdust/shavings in it? If so the ONLY thing to do with it is to put it on a pile and compost it."
— Rodney R · HayTalk thread 12580
The counter-position, from a grower who has spread it for years:
"We spread horse manure mixed with sawdust on a 20 acre field right next to my farm and the PH is not effected like you all are stating."
— hayray · HayTalk thread 12580
Both observations can be true, and the resolution is that the primary mechanism is usually misidentified. As one grower noted mid-discussion:
"I've heard all kinds of things about sawdust/wood chips as compost. Several articles claim it won't harm the PH, but it ties nitrogen up instead."
— mlappin · HayTalk thread 12580
That is the better explanation. Wood bedding has a very high carbon-to-nitrogen ratio, and soil microbes decomposing it immobilize nitrogen — temporarily starving the crop of the very nutrient you were spreading manure to supply. The visible symptom is a yellow, backward-looking field, which is easy to mistake for an acidity problem. It is worth noting that manures more often raise soil pH than lower it: because limestone is fed to poultry, litter acts as a dilute liming material at roughly a tenth the strength of agricultural limestone. In UGA's five-year northwest Georgia trial, litter-treated plots held pH at 5.76 against 5.42 unfertilized and 5.18 under ammonium nitrate.
Practical handling of bedding-heavy stall waste:
- Compost it first, and give it real time. Growers with horse operations describe one to two years, turning the pile to aerate it. Fresh material is brown; finished compost is black and fine.
- Add nitrogen to the pile to speed decomposition — a common trick is spreading urea over the pile as you turn it, which supplies the nitrogen the microbes need so they take less from your field later.
- Switch bedding if you can. Straw composts far faster than shavings. Operations that moved to pelleted bedding report large reductions in total volume to handle.
- Spread in fall after last cutting so anything left has the winter to break down rather than being raked into next season's windrow.
That last point was the first piece of advice offered in the original discussion, and it holds for every manure type covered here:
"You could also spread it in the fall after last cutting and have the winter to breakdown in field.It should be broke down enough by then so it wouldn't get in the hay."
— swmnhay · HayTalk thread 12580
Frequently asked questions
How much poultry litter should I apply to a hayfield?
Common rates are 1 to 2 tons per acre per year on cool-season grass hay and up to about 4 tons per acre on bermudagrass, often split across the season. Many nutrient management plans cap application at 2 tons per acre per year. Always base the final rate on a current litter analysis and soil test.
How much nitrogen is available in a ton of chicken litter?
Broiler litter averages about 63 pounds of total nitrogen per ton, but only around half is available in the season you apply it, because roughly 89 percent of the nitrogen is organic and must be mineralized first. NC State uses an availability coefficient of 0.5 for broadcast application, giving about 29 pounds of plant-available nitrogen per ton.
Does poultry litter keep working in later years?
Not for nitrogen. University of Georgia reports that very little nitrogen carryover should be expected the second year after application. What does persist is the phosphorus and potassium contribution, improved soil organic matter, and a mild liming effect, since litter acts as a dilute liming material.
Can you spread manure on hay ground between cuttings?
Yes, and immediately after a cutting is the best in-season timing. The stubble is short so material reaches the soil, regrowth uses the nitrogen quickly, and you get the longest interval before the next cut for it to wash in. Avoid application close to harvest, and raise your rake so nothing is dragged into the windrow.
Is it safe to feed hay from fields fertilized with chicken litter?
Generally yes for cattle when litter is applied well before harvest and washed in by rain. The main hazard is botulism from litter containing decomposed carcasses, and UConn Extension lists poultry manure on horse hay ground as a risk factor. Many horse-hay producers avoid poultry litter entirely, or apply only in fall.
Why does phosphorus build up when using poultry litter?
Grasses need three to four times more nitrogen than phosphorus, but poultry litter contains almost equal amounts of both. Applying enough litter to meet nitrogen needs over-applies phosphorus every year. Alternate litter with commercial nitrogen, or apply litter to meet phosphorus needs and supplement nitrogen separately.
Should horse manure with sawdust go on hay ground?
Only after composting. Wood bedding has a very high carbon-to-nitrogen ratio, so soil microbes decomposing it tie up nitrogen and can starve the crop. Compost stall waste for a year or more until it is black and fine, add nitrogen to the pile to speed the process, and spread in fall.
The bottom line
Poultry litter and manure are good fertilizer for hay ground — they build organic matter, release nitrogen steadily across the season, buffer soil pH, and cost less per unit of nutrient than granular. But treat them as a nutrient source with a specific profile rather than as free fertilizer. Sample your own litter instead of trusting an average. Budget only about half the nitrogen for the year you apply it, and none for the year after. Watch phosphorus, because it, not nitrogen, is what will eventually cap your rate.
Then manage the part that is unique to hay. Everything you spread that does not wash into the soil is available to be picked up by a tedder or flicked into a windrow by a rake, and from there it goes into a bale. Apply in fall after the last cutting where you can, give it rain, raise your rake, and be conservative on ground destined for horse hay. The nutrients are worth having. Feathers in the bale are not.
The last link in that chain is the package. Everything your fertility program bought ends up in a bale that still has to survive the stack, and a bale that weathers through at the shoulders wastes those nutrients as surely as one full of litter. Full edge-to-edge bale net wrap holds a dense, weather-shedding bale so the tonnage you fertilized for actually reaches the feed bunk — see outdoor net-wrapped bale storage for how much that is worth over a winter.
Forum quotes are reproduced verbatim with attribution and linked to their source threads; follow the links to read the originals. Manure application rates and setbacks are regulated differently in every state and may require a nutrient management plan — check your state's requirements and soil test annually before making application decisions.
Featured photo: Manure Spreading, Angelrow Farm by James T M Towill, licensed under CC BY-SA 2.0, via Wikimedia Commons.
