Compost vs Manure: Nutrients, Safety and Rates Compared

Compost has about 0.9% nitrogen as sampled, solid dairy manure about 0.6% and broiler litter about 2.7%, based on lab results gathered by University of Maryland Extension (2017 to 2025). That is the core of compost vs manure: manure is a raw animal by-product with quick but uneven nitrogen, while compost is a stabilized material that feeds the crop slowly and is safer to handle. Farms do best by testing both and matching each to the crop and the date.

This guide compares the two on nutrients, speed, safety rules, soil structure and cost. It includes four charts from university data, a calculator that turns a lab report into a dollar value per ton, and a short list of mistakes to avoid. Rates and rules differ by state, so check your local extension office before you spread.

Compost vs manure: the short answer

Use manure when you need nitrogen for the current crop and can apply it early and work it in. Use compost when you want organic matter, a safer product for crops eaten raw, or a gentler nutrient supply. Use composted manure when you want a bit of both.

• Nitrogen: on the one compost factor published by the University of Nebraska–Lincoln (composted feedlot manure, 0.15), a smaller share of compost nitrogen is available in year one than from raw manure (0.40 for solid beef or dairy); see the chart below.
• Safety: raw manure carries pathogens and weed seeds, and organic rules set waiting times before harvest. Compost made to a set temperature schedule does not need those waits.
• Phosphorus and potassium: both materials carry them, and both can build them up in the soil if you size every load to the nitrogen need.
• Soil structure: both add organic matter, and organic matter raises the water a soil can hold.

What is the difference between compost and manure?

Manure is animal droppings, usually mixed with bedding. Compost is any organic material (crop residue, yard waste, food scraps or manure) that has been broken down by microbes under managed heat and air until it is stable and crumbly. Composted manure is both: manure that went through that process.

That is why people ask whether compost and manure are the same. They are not, although they can overlap. The USDA organic rules define compost as a managed process in which microorganisms break down plant and animal material into forms suitable for soil, as set out on the USDA Agricultural Marketing Service soil-building page.

Washington State University and Oregon State University extension staff say composting raw manure kills weed seeds and pathogens, helps storage and gives a more uniform product that is easier to apply (PNW533).

How much nutrient is in compost and in manure?

It depends on the animal, the bedding and the storage. The Maryland summary gathers thousands of lab analyses that were used for nutrient management plans in that state. Poultry litter sits far above the rest. Compost lands in the middle: above cattle and horse manure on nitrogen, in a similar range on phosphate, and below them on potash.

Chart

Total nitrogen in compost and manure

mean % N of the material as sampled, Maryland nutrient plan samples 2017 to 2025

Percentages in the chart are of the material as sampled, with moisture reported separately. Multiply by 20 to get pounds per ton, a conversion also used in the Pacific Northwest guide. Compost at 0.92% N is about 18 lb of nitrogen per ton; broiler litter at 2.71% is about 54 lb.

Source: University of Maryland Extension, Manure Summary Report, mean values for 2017 to 2025 samples (updated August 2026). Ranges inside each group are wide. The compost group, for example, runs from 0.18% to 3.19% total nitrogen, so one bag or load can differ a lot from the average.

Older tables give a similar picture. Utah State University lists poultry litter at 40 to 80 lb of nitrogen per ton, against 21 to 24 lb for dirt-lot beef manure (USU Extension), and the University of Arkansas gives 11 lb of nitrogen per ton for solid dairy manure (FSA4017).

How fast does the nitrogen reach the crop?

Total nitrogen is not the same as nitrogen the crop can use this season. Manure holds ammonium nitrogen, which plants can take up at once but which is lost as gas if the manure sits on the surface. It also holds organic nitrogen, which is released as microbes break it down.

Chart

Share of organic nitrogen available in year one

first-year availability factor, as % of organic N

The University of Nebraska–Lincoln worksheet gives first-year organic nitrogen factors of 0.40 for solid beef or dairy manure, 0.40 for swine, 0.40 for most poultry manure, 0.45 for layer manure without bedding and 0.15 for composted feedlot manure, the only compost factor in that table (UNL first-year availability worksheet). For ammonium nitrogen, the share kept depends on timing: 0.95 if manure is incorporated at once, 0.50 after one day for solid manure, and 0 if it lies on the surface before planting.

The Pacific Northwest guide adds that composts are lower in plant-available nitrogen than most raw manures, and that products sold as composted poultry litter are often only part composted and then behave like fresh litter.

How much nitrogen is lost before it is used?

Much of the nitrogen in manure is lost to the air or water before the crop sees it. The University of Arkansas gives ranges for dairy manure systems: 15 to 35% lost with daily scrape and haul, 40 to 60% from an open lot and 70 to 80% from a lagoon. Spreading adds a second loss: 15 to 30% for broadcast solid manure and 1 to 5% for injection (University of Arkansas, FSA4017).

Chart

Nitrogen lost before the crop can use it

% of N lost, low to high range, dairy manure systems

These figures are why a lab test of the manure you really spread beats any table. They are also a reason to cover stored manure and to incorporate it soon after spreading.

Safety rules: raw manure, composting and waiting times

Raw manure can carry pathogens that cause illness. Fresh manure is not a good choice for salad and root crops eaten raw, say the WSU and Oregon State authors in PNW533.

Organic growers in the United States follow the 90-120 day rule. Raw manure on a food crop must be worked in at least 120 days before harvest if the edible part touches the soil, or at least 90 days if it does not (7 CFR 205.203). The rule does not apply to fiber crops, cover crops or crops fed to livestock (USDA AMS).

Compost used in organic production must start at a carbon to nitrogen ratio between 25:1 and 40:1. It must then hold 131 to 170°F for 3 days in a vessel or aerated static pile, or for 15 days in a windrow turned at least five times (7 CFR 205.203). Small piles lose heat quickly and may not get hot enough to kill pathogens and weed seeds, notes the FAO guide to on-farm composting.

Non-organic farms follow state and buyer food-safety rules, which can differ. Check local rules, your buyer’s audit standard and the product label of any supplied compost before you apply anything.

Soil structure, organic matter and water

Both materials add organic matter. The University of Minnesota notes that organic matter helps form soil aggregates, and aggregates let water in and hold it for the roots. Manure used over many years can raise total soil organic matter (Cates, University of Minnesota, via UNL, 2020).

Chart

Extra water held per 1% more organic matter

plant-available water, gallons per acre, top 12 inches of soil

The same article puts numbers on it. In the top foot of soil, each 1% rise in organic matter raises plant-available water by about 3,400 gallons per acre in a silt loam, 3,700 in a loamy sand and 2,700 in a clay loam. That is roughly a ninth of an inch of rain for the silt loam. It is a modest gain, so judge compost and manure on nutrients, safety and cost first, and treat water holding as an extra.

▶ Why organic matter matters for soil and farming. · 7:33

Where humus fits

Humus is the dark, stable part of soil organic matter left after fresh material has broken down. Compost is close to that state when it is finished, which is why people link the two. Manure and compost add organic matter that feeds the process which builds humus over several seasons. Organic matter changes slowly, so judge the effect with soil tests over several years, not after one application.

Which should you use? A choice by situation

How to make compost on the farm

If you want to make your own, treat it as a managed process, not a pile left to rot. The FAO describes windrow composting as long, narrow piles that are turned on a regular basis to mix the material and let air in. Wet manure windrows should be lower than windrows of leaves, because a pile that is too big goes airless in the middle and gives off odors when turned (FAO).

1. Blend the feedstocks. Mix manure with a carbon source such as straw, wood chips or leaves. The organic standard asks for a starting carbon to nitrogen ratio between 25:1 and 40:1.
2. Build the windrow. Make it big enough to hold heat but small enough to breathe.
3. Measure the heat. Use a long thermometer and keep a log. The organic standard asks for 131 to 170°F for 15 days in a windrow, turned at least five times.
4. Cure and test. Let it settle, then send a sample to a lab and read the report before it goes on a crop.

Keep the piles away from ditches and wells, and check your state’s rules for on-farm composting before you start.

▶ Mixed farming explained: manure as fertilizer and other benefits of keeping crops and animals together. · 2:55

Is a compost and manure mix worth it?

A blend, or composted manure, can give some quick nutrient from the manure fraction and some slow supply from the compost fraction. The Pacific Northwest guide says thorough composting generally slows the release of manure nitrogen by locking it into more stable forms. So composting trades quick nitrogen for safety and storage. Mixing finished compost with fresh manure does not make the manure safe; treat any raw component as raw.

Because manures are unbalanced, applying them to meet the crop’s nitrogen need usually supplies more phosphorus and potassium than the crop uses. The authors advise soil tests for phosphorus and potassium every three to five years to avoid build-up. The same advice applies to compost sized to the nitrogen need.

What do compost and manure cost to haul and spread?

The nutrients in a load are only part of the price. The University of Arkansas points out that the cost of moving manure to the crop can come close to its value as fertilizer (FSA4017). Wet, heavy material costs more to carry per pound of nutrient. That favors dry, nutrient-rich products such as poultry litter for longer hauls, and it favors nearby sources for the rest.

Use the calculator below to find the break-even price per ton at today’s fertilizer prices. If a supplier asks more than that, you are paying for organic matter, convenience or safety, which can be a fair reason, but it should be a choice. Prices you see online may be dealer asking prices rather than what farms pay, and they change by region and season, so get two local quotes before you decide.

Work out what a ton is worth

The calculator below turns a lab report into the fertilizer value of one ton and of one acre. Enter your own numbers from the lab sheet and your local fertilizer prices. It counts only the nutrients a crop can use in year one, using the Nebraska factors above.

Try the numbers for your own farm below.

How much to apply and when

Start from the crop’s nitrogen need, subtract credits, then divide by the plant-available nitrogen per ton from your lab sheet. The Pacific Northwest guide explains this in worksheet form, with a calibration step for your spreader. Keep records field by field.

• Timing: spring before planting is the best time for manure on row crops from a nutrient point of view; fall application raises the risk of loss to leaching and runoff (PNW533).
• Sample first: ask for total nitrogen, ammonium nitrogen, phosphorus, potassium, salts and dry matter. A Penn State compost report shows what a typical lab sheet lists, including organic matter, carbon to nitrogen ratio and soluble salts.
• Salts: over-application of some products can damage plants through soluble salts (PNW533).
• Later years: some nitrogen is released in the following years, so credit it before the next application.

Follow local nutrient rules. Many states limit phosphorus or nitrogen from manure, set setbacks from water and ban spreading on frozen ground. Get advice from your extension office or a certified crop adviser.

Common mistakes to avoid

• Using table values instead of a test. The Pacific Northwest authors strongly advise testing, since not knowing the nutrient content can lead to large errors in rates.
• Leaving manure on the surface. The Nebraska table gives no ammonium credit for surface manure that is not worked in before planting.
• Sizing every load to nitrogen. That loads up phosphorus and potassium over the years.
• Trusting the label “composted.” Ask how it was made and see the test report; the PNW authors warn that some composted poultry litter is only part composted.
• Ignoring salts. Some products can hurt seedlings through soluble salts, which matters most in dry regions.
• Skipping records. Write down the source, the rate and the date for every field.

▶ Seven simple sustainable farming practices that protect soil and water. · 4:34

Checking how fields respond

After you spread, look at the field through the season. Satellite vegetation maps, such as those in Farmonaut Satellite + AI Farm Monitoring System, can show whether one zone greens up more slowly than another. They show plant vigour, not soil nutrients, so confirm a cause with a soil or tissue test.

FAQ

Is manure better than compost?

Neither is better in every case. Manure releases a larger share of its nitrogen in year one, and compost is safer to handle and releases nutrients more slowly. Choose on the crop, the date and the lab report.

Is compost the same as manure?

No. Manure is animal waste. Compost is any organic material broken down under managed heat and air, and it can include manure. Composted manure is manure that went through that process.

What is the difference between fresh manure and composted manure?

Fresh manure has more ammonium nitrogen and may carry pathogens and weed seeds. Composted manure has lost some nitrogen as gas and holds the rest in stable forms, so it releases less nitrogen in year one.

Can I put raw manure on a vegetable garden?

Only with care. Under the USDA organic rule, raw manure must go on at least 90 or 120 days before harvest, depending on whether the crop touches the soil. For salad and root crops eaten raw, composted material is the safer choice. Check local food-safety rules.

How often should I apply compost or manure?

Base it on the crop’s nitrogen need and on soil tests for phosphorus and potassium taken every three to five years. If the soil test shows high phosphorus, cut the rate or skip a year.

Does compost replace fertilizer?

Not fully. Compost is low in plant-available nitrogen in year one, so crops with a high nitrogen need may still need a supplement. Take advice from your extension office or crop adviser.

Conclusion

Manure is the quicker nitrogen source when it is tested, covered in storage and worked in early. Compost is the safer, steadier material and the better choice for raw-eaten crops. Read the lab sheet, apply to the crop need, test the soil, and keep the records.

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