Quick facts
- Manure nutrient management planning is important for maximizing crop productivity while protecting environmental quality.
- Recommendations for manure application rates vary depending on crop and cropping history.
- Manure application rates should be based on all nutrient sources that will be or have been applied to a field.
- Determining nutrient availability for the manure source is critical to calculate the rate of application needed.
- Manure application rates are only one piece of the puzzle. Timing and application method play an equally important role in retaining nutrients in the field.
Animal manure is a good source of nutrients for crops, including nitrogen (N), phosphorus (P), and potassium (K). However, the nutrient proportions in manure typically do not match specific crop nutrient needs. Manure application based on one nutrient may over- or underapply other required crop nutrients. Non-legume crops require the most nitrogen.
Applying manure to meet crop nitrogen needs will likely overapply phosphorus, and possibly potassium, for a crop such as corn. On the other hand, using manure to meet the P needs of the crop will likely result in underapplication of N and possibly K. Commercial fertilizers will then be needed to balance out N and K needs. Consider the pros and cons of these two options when choosing a manure application rate.
Nutrients in manure are not 100% available in the first year. First-year plant-available nitrogen (PAN) will depend on animal species and how the manure is applied. Plant-available phosphorus (PAP) is assumed to be 80% of the total P applied in the first year.
You can learn more about calculating PAN and PAP, including first-year PAN and PAP, from our calculating manure application rates recommendations.
The recommendations for manure application rates below are based on PAN or PAP, not total N and P in the manure.
Applying manure based on the nitrogen needs of the crop
The rates below are the maximum amounts of nitrogen to apply when using manure, whether it is all manure or a combination of manure and inorganic commercial fertilizers. You may consider lower rates based on soil productivity, economics, or environmental concerns. In all cases, all sources of N should be taken into consideration when estimating how much N to apply, including:
- Commercial fertilizer (including starter fertilizer).
- N from irrigation water.
- Credits from manure or other organic N sources that were applied in the past 2 years.
- Credits from legumes like edible beans, red clover, etc.
Research across the U.S. Midwest has shown that N applications above crop need in any given year significantly increase the potential for N losses. For example, once N leaches past the plant root zone, it can contaminate groundwater, which is a concern for drinking water, and pollute lakes, rivers, and streams.
Poor N management can also lead to gaseous losses that contaminate the atmosphere. When manure N becomes plant-available, it behaves in the environment in the same way as N from commercial inorganic fertilizer. All forms of N applied to the soil must be taken into consideration. Don’t waste your manure.
Nitrogen application rates for corn following corn or soybean, when manure is used, are based on historical corn yield for each field and a nitrogen-to-yield (N/yield) factor. What is “historical corn yield”? It is the average yield for a field over the past five corn growing seasons. If these data are not available, use the average county corn yield results for the past five years in the county where the field is located. This information can be accessed through the USDA National Agricultural Statistics Service. If there was a significant drought, flood, or other weather event that resulted in significant yield loss in a year, exclude that year from your average and use one year further back in your records.
For grain:
- The N/yield factor for corn following corn is 0.9 pounds of N per bushel of historical yield.
- For corn following soybean, it is 0.7 pounds of N per bushel of historical yield.
- Multiply your historical yield by the appropriate N/yield factor to determine your total PAN rate to apply per acre.
For silage:
Multiply historical silage yield (tons/acre at 65% moisture content) by 7.5 to get the grain yield equivalent. Then follow the recommendations for grain corn.
The maximum rate of plant-available nitrogen (PAN) to be applied with manure to non-irrigated grain corn, depending on the crop before corn (excluding alfalfa in the rotation).
| Crop before grain corn | Historical corn yield (bushels per acre) | N/yield factor | Maximum lbs of PAN to apply per acre |
|---|---|---|---|
| Soybean | 180 | 0.7 | 126 |
| Soybean | 200 | 0.7 | 140 |
| Soybean | 220 | 0.7 | 154 |
| Soybean | 240 | 0.7 | 168 |
| Corn | 180 | 0.9 | 162 |
| Corn | 200 | 0.9 | 180 |
| Corn | 220 | 0.9 | 198 |
| Corn | 240 | 0.9 | 216 |
The maximum rate of plant-available nitrogen (PAN) that should be applied with manure to non-irrigated silage corn, depending on the crop before corn (excluding alfalfa in the rotation).
| Crop before silage corn | Historical silage yield (tons per acre at 65% moisture) | Historical silage yield converted to grain yield (bushels per acre) | N/yield factor | Maximum lbs of PAN to apply per acre |
|---|---|---|---|---|
| Soybean | 15 | 113 | 0.7 | 79 |
| Soybean | 20 | 150 | 0.7 | 105 |
| Soybean | 25 | 188 | 0.7 | 132 |
| Soybean | 30 | 225 | 0.7 | 158 |
| Corn | 15 | 113 | 0.9 | 102 |
| Corn | 20 | 150 | 0.9 | 135 |
| Corn | 25 | 188 | 0.9 | 169 |
| Corn | 30 | 225 | 0.9 | 203 |
Why do these examples differ from fertilizer application rates recommended by the University of Minnesota?
All recommendations are based on nitrogen rate research trials conducted across Minnesota over the past two decades. The goal is to evaluate the agronomics of corn production while minimizing the risk of N losses from overapplication.
However, fertilizer-only application rates also take into consideration a third aspect: the economics of corn production (nitrogen cost versus corn prices). This is the Maximum Return to Nitrogen (MRTN) method.
Since the economics of manure application are quite different and incredibly variable across farms, the MRTN method is not applicable when using manure for the growing season in which it is applied.
Alfalfa supplies soil nitrogen to following crops for several years after termination. Research in Minnesota has shown that the amount of N supplied depends on how old the stand was before termination.
The following table shows the maximum plant-available N to apply when manure is used.
The maximum rate of plant-available nitrogen (PAN) that should be applied with manure to non-irrigated corn when alfalfa was the previous crop in the past one to two years.
| Crop before corn | Crop 2 years before corn | Maximum lbs of PAN to apply |
|---|---|---|
| Corn | Alfalfa (1-year-old stand) | 120 |
| Corn | Alfalfa (2+ year-old stand) | 80 |
| Alfalfa: 1-year-old stand | Not applicable | 80 |
| Alfalfa: 2+ year-old stand | Not applicable | 40 |
Corn grown under irrigation is a special case because it is usually done on coarse-textured (or sandy) soils. Under these conditions, there is a higher risk of N loss due to the high leaching potential of these types of soils.
With manure, other nutrients could potentially be lost through leaching. Because of this, we suggest a split application of nitrogen: apply a lower rate of manure in the spring before planting, then supplement with commercial N fertilizers to meet total N needs.
We do not recommend fall application of manure on sandy soils.
Nitrogen recommendation for irrigated corn
A good approach is to apply a lower rate of manure (80% of the recommended N rate listed or use the P application rate), then add the remaining N as commercial fertilizer.
- If soybean was planted before corn, apply 205 pounds of PAN.
- If other crops were planted before corn, apply 235 pounds of PAN.
The maximum amount of PAN you should apply to non-legume crops with manure should follow University of Minnesota guidelines for nitrogen fertilizers.
Nitrogen guidelines for other non-legume crops
- Barley
- Buckwheat
- Canola
- Hay and pasture grasses
- Grass-legume mixtures
- Oat
- Potato (irrigated)
- Rye
- Sugarbeet
- Sunflower
- Wheat
Nitrogen guidelines for legume crops
We recommend applying manure at a phosphorus-based rate for legume crops.
Applying manure based on the phosphorus needs of the crop
Where manure is readily available, using a phosphorus-based manure application rate may make the most long-term economic sense, as the crops will use the nutrients more efficiently.
For manure, it is recommended to apply as much plant-available phosphorus (PAP) as the crop will use.
The following table shows crop phosphorus removal rates in the harvested portion (units are in P2O5, which is comparable to what you would apply with commercial fertilizer). Multiply this number by the yield you expect from a field to get your PAP application rate.
Note that soil testing should be conducted regularly in your fields where manure will be applied. If the soil P test level is very high (over 21 ppm Bray-P or over 16 ppm Olsen-P), you are not likely to see a yield benefit from the additional P in the manure. Instead, consider using the manure in a field where P applications will help improve yields.
If soil test P levels are excessively high (over 50 ppm Bray-P or over 30 ppm Olsen P), we do not recommend applying manure, especially near water bodies, because building soil test P levels further will increase the risk for soluble P losses from the soil.
Once you determine your P-based application rate, remember to credit the manure for the nitrogen applied. Balance the remaining N needs of the crop with commercial fertilizers (see recommendations above for N rates when using manure).
Amount of phosphorus removed per unit of harvested yield.
| Crop | Yield units | Crop P2O5 removal in pounds (per yield unit) |
|---|---|---|
| Alfalfa | Tons (air dry) | 12 |
| Barley (grain) | Bushels | 0.4 |
| Barley (grain and straw) | Bushels | 0.56 |
| Canola | Cwt. | 1.6 |
| Corn (grain) | Bushels | 0.35 |
| Corn (silage) | Tons (as fed) | 3.1 |
| Edible beans | Cwt. | 1.3 |
| Grass or hay pasture | Tons (air dry) | 17* |
| Grass/legume | Tons (air dry) | 13* |
| Oats (grain) | Bushels | 0.28 |
| Oats (grain and straw) | Bushels | 0.44 |
| Peas | Cwt. | 0.23* |
| Potatoes | Cwt. | 0.15 |
| Red clover | Tons (air dry) | 12 |
| Rye (grain) | Bushels | 0.46 |
| Rye (grain and straw) | Bushels | 0.67 |
| Soybeans | Bushels | 0.73 |
| Sugarbeets | Fresh Tons | 1.3* |
| Sunflower | Cwt. | 0.97 |
| Sweet corn | Tons | 2.8* |
| Wheat (grain) | Bushels | 0.57 |
| Wheat (grain and straw) | Bushels | 0.73 |
Sources: International Plant Nutrition Institute, 2014; *University of Michigan, 1992; Dan Kaiser, 2026
Reviewed in 2026