Ohio State University Extension

Ohio State University Extension
Department of Horticulture and Crop Science
2021 Coffey Road, Columbus, Ohio 43210-1044

Best Management Practices: A Manure Nutrient Management Program



There has been a great deal of interest in the management of animal manures in Ohio. This interest has been triggered by claims that animal manure may be part of the culprit in non-point pollution cases. Possibly the increased emphasis is due to the realization that manures contain very valuable plant nutrients. In any event, the State Legislature recently granted seed monies to assist Ohio farm producers to develop manure nutrient management programs.

Enough manure is generated in Ohio annually to satisfy half of the agricultural phosphorus demand. However, projections from USDA indicate that only 17% of the corn, 8% of the soybean and 5% of the wheat acreage in Ohio actually receives applications of manure.

The Ohio Department of Natural Resources, Soil and Water Conservation Division, is directing the effort. In addition, Ohio State University Extension and the Soil Conservation Service is playing a vital role in the Manure Nutrient Management (MNM) program.

Manure Application Strategies

The two strategies for manure use are: (1) management for maximum nutrient efficiency, and (2) management for maximum application rate of manure. If maximum nutrient efficiency is the goal, rates of application need to be based on the nutrient present at the highest level in terms of crop needs. In most cases this is phosphorus. Manure should be applied at a rate which will meet the crop"s requirement for P. Additional nitrogen and potassium can be supplied with commercial fertilizers. This strategy is least likely to cause undesirable environmental effects, and makes the most efficient use of all nutrients in manure.

The other strategy for utilizing manure on cropland is to determine a rate of application which will satisfy the crop"s requirement for nitrogen without causing environmental problems. This strategy maximizes the rate of applications, making less efficient use of P and K than the other strategy.

A manure application strategy based on crop N requirements will lead to an accumulation of P in the long term, especially with repeated applications. Excessive soil test levels of P can result in surface water quality problems.

Manure - a Valuable Resource

Let's assume that a producer handles his livestock manure in a manner which prevents the loss of nutrients. If we assess a value of $0.22 per pound for nitrogen, $0.20 per pound of phosphorus and $0.10 per pound for potassium:

How to Get Started

In order to determine the real value of your farm's manure, contact your county Extension agent or Soil and Water Conservation District. They will assist you in the following steps:

  1. Fields to receive manure should be soil tested for available nutrients prior to application. Your county Extension agent has the necessary soil test bags, forms and equipment.

  2. The manure must be analyzed for N, P, K, and other nutrients. Recent research shows that there are wide variations of nutrients in livestock manure. Using averages is not a good substitute for your own manure analysis. Contact your county Extension agent for manure test kits.

  3. Determine the nutrients needed for each field using the Manure Management Worksheet or the Crop Nutrient Management Computer Program.

  4. Develop a manure nutrient management plan for your farm. This can be done with the assistance of the local Soil and Water Conservation District and the soil conservationist.

Manure Management Worksheet

(Worksheet for determining manure application rates)
EXAMPLE 1: Swine manure
                                             EXAMPLE          FARM

1.   Determine nutrients needed to grow crop:                 ____
     a.    Crop and yield goal (corn)        150 bu/A         ____
     b.    Nutrient needs of crop based on current
           soil test report and Agronomy Guide
           pH = 6.3                          N=200 lb         ____
           LT1 = 68                          P2O=0 lb         ____
           P1 = 65 ppm (130 lb/A)            K2O=0 lb         ____
           K = 240 ppm (480 lb/A)                             
           Ca = 1500 ppm (3000 lb/A)                          
           Mg = 320 ppm (640 lb/A)                            
           CEC = 11 Meq/100g                                  

2.   Determine the type of manure recommendation for this field. The
     soil test P value is high enough that no phosphorus is
     recommended. Bray P1 levels above 60 rarely result in crop
     yield responses. However, based upon a low runoff potential of
     field and the soil test P values below 250 lb/A, the producer
     could apply enough manure to meet the nitrogen needs of the
     corn crop. See Table 1.
                                             Nitrogen Std.    ____

3.   Determine amount of manure needed to supply nitrogen needs:
     Example: Nitrogen needs = 200 lb/A
           Manure is applied in March and not incorporated. If no
           manure analysis is available, use standards in Table 2
           or 3.
     a.    Available nitrogen per ton:       2.82 lb/ton      ____
           NH4 - N = 6 lb X Efficiency Rate of 5% for unincorporated
           =                1.5 lb
           Organic N = 4 lb X Efficiency Rate
           of 33% =                          1.32 lb
                 (See Table 4 for Efficiency Factors)
     b.    Tons of manure needed to supply total N needs:
           200 lb N/2.82 lb/T manure =       71 tons          ____
     It would not be practical to apply 71 tons of manure per acre.
     A maximum of 20 to 30 tons should be applied per year. Let"s
     assume that 20 tons are applied and any shortfall of nitrogen
     is made up with commercial fertilizer.

4.   Calculate nutrients supplied by manure:
     a.    Total available N =
           2.82 lb/Ton X 20 Ton/A =               56.4 lb/A        ____
     b.    Total available P2O5 =
           9 lb/Ton X 20 Ton/A =                  180 lb/A         ____
     c.    Total available K2O =             
           8 lb/Ton X 20 Ton/A =                  160 lb/A         ____

In this example enough phosphorus and potassium are being supplied,
but nitrogen must be supplemented. 200 lb N - 56.4 lb = 143.6 lb N/A
to be supplied with commercial fertilizer.


EXAMPLE 2:  Let's assume the same situation as in EXAMPLE 1 except
the runoff is high and the farm cannot incorporate the manure below
the tillage zone.

1.   Determine the type of manure recommendation for this field from
     Table 1. The most manure that can be applied is equal to the
     P2O5 removed in the harvested crop.
                                       Phosphorus Std.        ____

2.   Determine P2O5 crop removal (See Agronomy Guide):
     150 bu corn X 0.37 lb/bu =                   55 lb/A     ____

3.   Calculate manure required to meet crop removal rate:
     55 lb P2O5/A/9 lb/Ton in manure =            6.1 tons    ____

TABLE 1. Recommended Maximum Manure Application Rates at Different Soil Test Levels.1

Bray P-1 Level
ppm (lb/A)
Surface Applied
on High Runoff
Potential Sites2
Incorporated or Low Runoff Potential Sites3
0-30 (0-60) N needs of non-legume crops; N removal rate of legume crops N needs of non-legume crops; N removal rate of legume crops
30-1254 (60-250) N needs or P removal rate for non-legume crop, whichever is less N or P removal rate for non-legume crops, whichever is less N needs of non-legume crops N removal rate for legume crops
125-1504 (250-300) Manure application for crop production purposes not recommended N needs or P removal rate for non-legume crops, whichever is less; N or P removal rate for legume crops, whichever is less
Over 1504 (Over 300) Manure application for crop production purposes not recommended Application of manure for crop production purposes is not recommended. If application is necessary, apply no more manure than supplies N or P removal for next crop, whichever is less. A site plan which controls erosion and runoff is recommended.
1 Applications of manure at rates above these recommendations may require approval and/or permits by appropriate government agencies.
2 Surface application is any application at a depth which would be disturbed by tillage within the next three years. High runoff potential refers to sites where surface movements of manure and/or phosphorus are likely to occur from the field of application.
3 Incorporation is any application at a depth which would NOT be disturbed by tillage within the next three years. Low runoff potential refers to sites where surface movement of manure and/or phosphorus from the field of application is not likely to occur under normal weather conditions.
4 Yearly plant tissue and soil analysis is recommended.

TABLE 2. Solid System1
Approximate quantity per 1000 lb animal equivalent per year and fertilizer nutrient composition of various types of animal manure at time applied to the land.

Type of livestock Bed vs. no bedding Tons Dry matter Total N NH4 P2O52 K2O3
% lb/ton
Swine /bedding 6.1 18 8 5 7 7
w/o bed 6.1 18 10 6 9 8
Beef cattle w/bedding 2.6 50 21 8 8 26
w/o bed 2.5 52 21 7 4 23
Dairy cattle w/bedding4 9.1 21 9 5 4 10
w/o bed 10.6 18 9 4 4 10
Sheep w/bedding 6.5 28 14 5 9 25
w/o bed 6.5 28 18 5 11 26
Poultry w/litter 4.4 75 56 36 45 34
w/o litter 7.3 45 33 26 48 34
Poultry deep pit (compost) 4.3 76 68 44 64 45
Turkey w/litter 7.2 29 20 13 16 13
w/o litter 9.5 22 27 17 20 17
Horses w/bedding 3.7 46 14 4 4 14
1 Manure spreader capacity: 1 bu = 40-60 lb.
2 To convert to elemental P, multiply by 0.44.
3 To convert to elemental K, multiply by 0.83.
4 Open dirt lot.

TABLE 3. Liquid System1
Approximate quantity per 1000 lb animal equivalent per year and fertilizer nutrient composition of various types of animal manure at time applied to the land.

Type of livestock Manure Storage 1000 Gal/yr Dry matter Total N2 NH43 P2O5 K2O
% lb/1000 gal
Swine Liquid pit 6.5 4 36 26 27 22
Lagoon4 26.2 1 4 3 2 4
Beef cattle Liquid pit 2.8 11 40 24 27 34
Lagoon4 30.6 1 4 2 9 4
Dairy cattle Liquid pit 3.3 8 24 12 18 29
Lagoon4 26.2 1 4 2.5 4 5
Veal Liquid pit -- 3 24 19 25 51
Poultry Liquid pit 6.0 13 80 64 36 96
1 Application conversion factors: 1000 gal = about 4 tons; 27,154 gal = 1 acre inch
2 Ammonium N plus organic N, which is slow releasing
3 Ammonium N, which is available to the plant during the growing season
4 Includes feedlot runoff water and is sized as follows: single cell lagoon-2 cu ft/lb animal wt; two cell lagoon-cell 1, 1-2 cu ft/lb animal wt. and cell 2, 1 cu ft/lb animal wt.

Computer Program

Manipulating the Manure Nutrient Management Worksheet can be quite time consuming. Because of this a much more efficient and accurate computer program has been developed by Ohio State University Extension. The required inputs to run the program are as follows:

- Field soil test analysis
- Manure test analysis
- Crop to be grown and the yield goal
- Method and time of manure application
- Typical fertilizer ingredient prices

The computer program output results include:

- Tons or gallons of manure to be applied per acre in order to balance the crop nutrients required
- Dollar value of manure to be applied
- Amounts and analysis of any additional commercial fertilizer that should be applied.

Contact your county Extension agent or Soil and Water Conservation District technician to assist in running the "Crop Nutrient Management" computer program. The software is available at county Extension offices for a nominal charge.

TABLE 4. Calculating the Efficiency of N Availability in Manures.

% Available Date of
# Days Until
NH4 Organic N
50 33 Nov-Feb 5 or less
25 33 Nov-Feb over 5
50 33 Mar-Apr 3 or less
25 33 Mar-Apr over 3
75 33 May-Jun 1 or less
25 33 May-Jun over 1
75 15 Jul-Aug 1 or less
25 15 Jul-Aug over 1
25 33 Sep-Oct 1 or less
15 33 Sep-Oct over 1
NOTE: The calculations are for all animal manures. Nearly 100% of total P and K are considered available the first growing season after application of all manures.


Livestock manure BMP's (Best Management Practices) are a combination of structural practices, including manure and wastewater storage, and management practices, including the rate, method, and timing of manure field applications.

Good nutrient management involves routing soil testing to determine the existing nutrient stocks. Fields receiving manure should be tested for available nutrients prior to application. The manure should also be tested. Application rates should be determined using the results of these tests.

Phosphorus and potassium in manure accumulate in the soil in the same manner as commercial fertilizer. In order to maximize yields and profits, farmers must account for carryover nutrients to accurately determine crop needs and manure applications.

Prepared by:
BMP Team:
Dr. Jay Johnson-Extension Agronomist
Dr. Mark Loux-Extension Agronomist
George Ropp-Agricultural Consultant
James Adams-Agricultural Consultant

All educational programs conducted by Ohio State University Extension are available to clientele on a nondiscriminatory basis without regard to race, color, creed, religion, sexual orientation, national origin, gender, age, disability or Vietnam-era veteran status.

Keith L. Smith, Associate Vice President for Ag. Adm. and Director, OSU Extension.

TDD No. 800-589-8292 (Ohio only) or 614-292-6181

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