Swine Manure as a Fertilizer Source

Prepared by:
J. P. Zublena
 Extension Soil Science Specialist

J. C. Barker
Extension Agricultural Engineering Specialist

J. W. Parker
Extension Area Swine Specialist (retired)

C. M. Stanislaw
Extension Swine Specialist

Published by: North Carolina Cooperative Extension Service

Publication Number: AG 439-4

Last Electronic Revision: March 1996 (JWM)

Swine manure can be an excellent source of nutrients for crop production. The key to proper management is determining the nutrient content of the manure, the percentages of those nutrients that are available to the plant, and the nutrient requirements of the plant. Considered together, these three factors will help you apply the proper amount.

Nutrient Content of the Manure

Because the nutrient content of swine manure varies among operations and over time, the manure must be analyzed before you apply it to the land. Waste samples can be analyzed for $4.00 by contacting the North Carolina Department of Agriculture (NCDA), Agronomic Division, Plant and Waste Analysis Lab, P.O. Box 27647, Blue Ridge Road Center, Raleigh, NC 27611. Other qualified private laboratories are also available (fees vary).

Samples collected for analysis should be representative of the pit or lagoon. If the waste is to be applied as a slurry, the storage pit or basin should be agitated before sampling. Collect approximately 3/4 of a pint of material in an expandable container, being sure to leave air space.

If you cannot have a sample analyzed, determine the application rate by using the average nutrient values for different swine manure systems shown in Table 1.

Table 1. Nutrient Composition of Swine Manure


Manure 	          Total	  Ammonium	 Phosphorus	Potassium
 Type 	          N	  NH4- N	 P2O5	        K2O
------------------------------lb/ton-----------------------------
Fresh	          12	  7	         9	        9
Scraped1	  13	  7	         12	        9
-------------------------lb/1,000 gallons------------------------
Liquid slurry2	  31	  19	         22	        17
Anaerobic 	
lagoon sludge	  22	  6	         49	        7
----------------------------lb/acre-inch--------------------------
Anaerobic
lagoon liquid  	 136	  111	         53	         133

Source: Abridged from North Carolina Agricultural Chemicals Manual.
1Collected within 1 week.
2Six-12 months accumulation of manure, urine, and excess water usage; does 
not include fresh water for flushing or lot runoff.

Table 2 shows the average amounts of secondary and micronutrients present in swine manures. These values can be used as planning guidelines, as long as you realize that they are not as accurate as a sample analysis.

Table 2. Secondary and Micronutrient Content of Swine Manures

 
ManureType  	     Ca	    Mg    S     Na    Fe     Mn     B       Mo 	      Zn    Cu 
-----------------------------------------------lb/ton------------------------------------
Fresh  	             7.9    1.7	  1.8	1.6   0.39   0.04   0.074   0.00066   0.12  0.029
Paved lot scraped    12.0   2.3	  2.2	1.6   1.03   0.19   0.015   0.00007   0.35   0.15
-------------------------------------------lb/1,000 gallons------------------------------
Liquid slurry        8.6    2.9	  4.7	3.7   0.69   0.15   0.069    0.0011   0.39   0.11
Lagoon sludge        15.8   4.5	  8.3	2.9    1.8   0.28   0.023    0.0095   0.67   0.23
----------------------------------------------lb/acre-inch-------------------------------
Lagoon liquid	     25.5   8.3	  10.0	57.7   2.4    .34    0.18    0.0045    1.5    0.3

Source: Biological and Agricultural Engineering Department, NCSU.

Nutrient Availabilities

The total nutrient content reported on a manure analysis report (or the levels shown in Tables 1 and 2) is not immediately available to the crops when the manure is applied. Some elements are released when the organic matter is decomposed by soil microorganisms. Other elements can combine with soil constituents and be made unavailable. Nitrogen may also be lost to the atmosphere through volatilization or denitrification, depending on the application method and soil moisture levels.

Table 3 lists the proportion of nutrients available for crop use during the first year of application for given application methods. When determining the application rate, refer to the availability coefficient for the appropriate application method, and then multiply that number by the corresponding nutrient value on the waste analysis report (or by the values shown in Tables 1 and 2). Waste analysis reports from the NCDA's Agronomic Division show the nutrient availabilities for the first crop.

The most recently applied waste is not the only source of nutrients; they are also available from previous applications of manures or from legumes crops. With the exception of nitrogen, updated soil tests are the best means of determining nutrient reserves from manure applications. Table 4 can be used to estimate available nitrogen carry-over from legumes.

Table 3. First-Year Availability Coefficients for Swine Manure


Manure	                                   Soil
Type	                   Injection1  Incorporation2	Broadcast3  Irrigation4

                           --------P2O5 and K2O availability coefficients----------
All manure types	   0.8	       0.8	         0.7	     0.7

                           ---------------N availability coefficient---------------
Scraped paved surface	    - 	       0.6	         0.4   	—     -
Liquid manure slurry	   0.8	       0.7	         0.4	     0.3
Anaerobic lagoon liquid	   0.9	       0.8	         0.5	     0.5
Anaerobic lagoon sludge	   0.6	       0.6	         0.4	     0.4
   
1Manure injected directly into soil and immediately covered.
2Surface-spread manure plowed or disked into soil within two days.
3Surface-spread manure uncovered for one month or longer.
4Sprinkler-irrigated liquid uncovered for one month or longer.

Table 4. Estimated Residual Nitrogen Provided by a Good Stand of Legumes Grown in Rotation

 
Legume	           Residual Nitrogen Available
                            (lb/acre)
Alfalfa1	             80-100
Harry vetch1	             80-100
Crimson clover1	             60-75
Austrian winter pea1         50-60
Soybeans2	             15-30
Peanuts2	             20-40

1Killed before planting current spring crop.
2Legume planted in previous year or season.  More nitrogen will 
be available if the fall-planted crop immediately follows the 
legume. On sandy soils and in years with normally high 
precipitation, less nitrogen will be available to spring-planted crops.

Application Rates

Land application rates of manure are generally determined by matching the available nitrogen or phosphorus content of the wastes to the nutrient requirements of the crops. In most cases, nitrogen determines the application rate unless the area is designated "nutrient sensitive" and indicates that phosphorus movement off-site could contaminate surface waters. In areas not designated as nutrient sensitive, phosphorus movement can be adequately controlled with conservation methods that minimize soil and nutrient runoff. The conservation methods include grass field borders, grassed waterways, contour planting, and reduced tillage. Leaching of phosphorus is extremely limited on mineral soils and should not contribute to groundwater contamination.

Nitrogen recommendations for various crops are listed in Table 5. Use these rates as guidelines with the realistic yield capabilities for each crop and field. With feed and forage crops, excessive manure application can produce high nitrate concentrations, which can harm livestock (through nitrate poisoning) and promote nutrient imbalances that may lead to grass tetany. If loading rates are based on phosphorus, apply the amount suggested by soil test recommendations. Other nutrients such as potassium, magnesium, and the micronutrients manganese, zinc, and copper may not be supplied in sufficient quantities for normal crop production. In such cases, apply the supplemental nutrients with a commercial fertilizer as recommended by a current soil test.

In addition to the supply of nutrients, proper soil pH is required to promote organic matter decomposition, improve crop yields, and ensure nutrient availability. The biological conversion of organic matter to nitrate is an acid-forming process that will continue to reduce soil pH unless you follow an adequate sampling and liming program.

To help you determine land application rates, a worksheet is provided at the end of this publication.

Timing of Manure Applications

In addition to carefully calculating the application rate, you must also minimize the delay between applying the manure and planting the crop. Precise timing increases the amount of nitrogen used by the crop and thus reduces leaching. The risk of surface water and groundwater contamination is greater in areas of high rainfall and where manures are applied in the fall or winter for spring crops. On sandy-textured soils, apply manures at low rates throughout the growing season, wherever possible, to reduce nitrogen leaching caused by the soil's low nutrient-holding capacity.

Exercise caution when applying lagoon liquid through irrigation onto standing crops that are undergoing stresses.

Acreage Requirements for New Facilities

Whenever samples of manure or lagoon liquid are available for analysis, the specific results should be used to determine application rates and acreage requirements. However, when you are planning new facilities, average values can help determine the approximate acreage requirements for a given size swine operation. Table 6 can be used to determine the minimum acreage a new unit will need for manure use.

An example will make these methods clear. A producer is interested in starting a 500-sow farrow- to-finish operation using an anaerobic lagoon collection system. The producer is considering spraying the lagoon liquid effluent on bermudagrass being grown for hay. The realistic yield expected for this field is 6 dry tons per acre. How many acres of bermudagrass would be needed?

Using Table 5, the maximum nitrogen (N) rate required is 300 lb per acre (6 tons x 50 lb N/ton). Go now to Table 6 under surface broadcast column 300, and you will find that each sow would require 0.0867 acres to utilize its waste. A 500-sow operation would thus require 43.4 acres

(0.0867 x 500 = 43.4).

Value of Manure

To compare the value of manure to commercial fertilizer, convert the manure nutrients to available nutrients by using their availability coefficients. In the example that follows, the amount of available nitrogen (N), phosphorus (P2O5), and potassium (K2O) in each inch of lagoon liquid is approximately 68, 37, and 93 pounds per acre, respective-ly. At $0.225 per pound of nitrogen, $0.22 per pound of phosphate, and $0.12 per pound of potash, the manure's gross worth is

(68 x $.225) + (37 x $.22) + (93 x $.12)

or

$15.30 + $8.14 + $11.16 = $34.60 per acre for each inch of lagoon liquid.

This value does not include labor or irrigation equipment costs, nor does it include the value of any secondary or micronutrients available in the manure. In addition, it assumes that the soil test has indicated a need for each nutrient, when, in fact, many nutrients may not be needed. Nutrients not needed should not be considered in assessing the financial value of the manure.

Table 6. Minimum Amount of Land Needed to Apply Swine Manure as a Nitrogen Fertilizer Based on the Nitrogen Rate Required by the Crop.


	                        Soil Incorporated1 	        Surface Broadcast2
	                                           lb N/acre/year 
	                        100    	200	300	400	100	200	300	400
                                             Acres/animal unit capacity
Paved Lot Scraped Manure
Weanling-to-feeder per head	0.025	0.012	0.0082	 0.0062	0.0158	0.0074	0.0049	0.0037
Feeder-to-finish per head	0.12	0.061	0.041    0.030	0.073	0.036	0.024	0.018
Farrow-to-weanling per sow	0.29	0.14	0.095	 0.071	0.17	0.085	0.057	0.043
Farrow-to-feeder per sow	0.34	0.17	0.11	 0.086	0.21	0.10	0.069	0.051
Farrow-to-finish per sow    	1.4	0.70	0.47	 0.35	0.84	0.42	0.28	0.21
Liquid Manure Slurry
Weanling-to-feeder per head	0.031	0.015	0.010	 0.0077	0.019	0.0095	0.0063	0.0047
Feeder-to-finish per head	 0.15	0.076	0.051	 0.038	0.094	0.0470	0.031	0.023
Farrow-to-weanling per sow	 0.36	0.18	0.12	 0.089	0.22	0.11	0.073	0.055
Farrow-to-feeder per sow	 0.43	0.21	0.14	 0.11	0.26	0.13	0.088	0.066
Farrow-to-finish per sow	  1.7	0.87	0.58	0.44	1.1	0.54	0.36	0.27
Anaerobic Lagoon Sludge
Weanling-to-feeder per head	0.0019	0.0010	0.0006	 0.0005	0.0016	0.0008	0.0005	0.0004
Feeder-to-finish per head	0.0094	0.0047	0.0031	 0.0024	0.0078	0.0039	0.0026	0.0019
Farrow-to-weanling per sow	0.015	0.0074	0.0049	 0.0037	0.018	0.0091	0.0061	0.0046
Farrow-to-feeder per sow	0.018	0.0089	0.0059	 0.0044	0.022	0.011	0.0073	0.0055
Farrow-to-finish per sow	0.11	0.054	0.036	 0.027	0.089	0.045	0.030	0.022
Anaerobic Lagoon Liquid
Weanling-to-feeder per head	0.0075	0.0038	0.0025	0.0019	0.0048	0.0024	0.0016	0.0012
Feeder-to-finish per head	0.037	0.018	0.012	0.0092	0.023	0.012	0.0078	0.0058
Farrow-to-weanling per sow	0.084	0.042	0.028	0.021	0.054	0.027	0.018	0.013
Farrow-to-feeder per sow	0.10	0.051	0.034	0.025	0.065	0.032	0.022	0.016
Farrow-to-finish per sow	0.41	0.21	0.14	0.10	0.26	0.13	0.088	0.066

1Incorporated within 2 days

Land Application Worksheet

Farmer Jones has a swine operation in which lagoon liquid is applied through a travel gun to fertigate a field for corn. His yield goal is about 120 bushels per acre, and he decides to apply the equivalent of 120 pounds of nitrogen per acre (Table 5). His land is not subject to erosion, nor is it in a nutrient sensitive watershed. The corn crop will be planted in the same field that had soybeans last year. He has grass borders on his field to further reduce the potential of nutrient or pesticide runoff.

Farmer Jones uses a starter fertilizer on his corn crop at a rate to supply 10 pounds of nitrogen per acre and 34 pounds of P2O5 per acre. He intends to supply the remainder of nitrogen from liquid swine lagoon effluent. How much effluent does he need to apply to meet the nitrogen needs of his corn crop? How much will be needed to supplement the crop with additional K2O or P2O5 to satisfy his soil test recommendations of 50 pounds of each nutrient per acre? The answers are given in the worksheet.

Worksheet: Determining the Nutrient Needs of Your Crop


                                                            Example      Your Farm 

1.Crop to be grown                                           corn  
2.Total nutrients required
		a.	N (Table 5) (lb/acre)                120
		b.	P2O5 (soil test) (lb/acre)            50  
		c.	K2O (soil test) (lb/acre)             50       
3.Pounds of starter or preplant fertilizer used             
		a. 	N (lb/acre)                           10        
		b. 	P2O5 (lb/acre)                        34        
		c.	K2O (lb/acre)                         0        
4. Residual N credit from legumes (Table 4) (lb/acre)         20        
5. Net nutrient needs of crop (lb/acre)
   Nitrogen:  Total need (item 2a) minus 
   starter (item 3a), minus legume (item 4)
		a. 	N: 120 –10 20(lb/acre)                 90
   Phosphorus and potassium: Total need (items 2b and 2c) 	
   minus additional nutrients from starter (items 3b and 3c)
		b. 	P2O5: 50 – 34 (lb/are)                 16        
		c. 	K2O: 50 – 0 (lb/ace)                   50
RATE OF MANURE TO APPLY
6.Nutrient totals in manure (from Table 1 or waste samples). 
  If analysis report already gives available nutrients, 
        skip this item.
		a. 	Total N (lb/acre-inch)                136 
		b. 	P2O5 (lb/acre-inch)                    53 
		c. 	K2O (lb/acre-inch)                    133 
7.Nutrients available to crop (items 6a, 6b, and 6c) times 
  availability coefficients (Table 3)
		a.	Available N: 136 x 0.5 (lb/acre-inch)  68
		b. 	Available P2O5: 53 x 0.7 (lb/acre-inch)37
		c. 	Available K2O: 133 x 0.7 (lb/acre-inch)93
8.Application rate to supply primary nutrient
		a. 	Priority nutrient    
		b. 	Amount of priority nutrient needed 
                        (lb/acre from item 5a)                 90
		c. 	Rate of manure needed to supply 
                        priority nutrient(item 8b)/(item 7a):
                        90/68 (acre-inch)	             1.32
9.Pounds per acre of all nutrients supplied at the application 
rate required to meet the needs for the priority nutrient. 
For each nutrient, multiply the available nutrients 
(items 7a, 7b, and 7c) by manure rate (item 8c).
		a. 	N supplied: 68 x 1.32 (lb/acre)        90
		b. 	P2O5 supplied: 37 x 1.32 (lb/acre)     49 
		c. 	K2O supplied:  93 x 1.32 (lb/acre)    123
10.Nutrient Balance:  Net nutrient need (–) or  excess (+)
 after application of manure at calculated rate. Subtract 
the net nutrient needs of the crop(items 5a, 5b, and 5c) 
from the nutrient rate applied (items 9a, 9b, and 9c).
		a. 	N balance: 90 – 90  (lb/acr)            0
		b. 	P2O5 balance: 49 – 16 (lb/ace)        +3
		c. 	K2O balance: 123  – 50 (lb/acr)       +73
       
Source: Calculation format modified from Pennsylvania Department of 
Environmental Resources, Field Application of Manure,	
October 1986.

The authors wish to acknowledge the assistance and cooperation of the North Carolina Department of Agriculture's Agronomic Division in the analysis of samples and the development of the data base used in this publication.
Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age, or disability. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
AG 439-4