Manure and Pasture Management for Horse Owners: Managing Manure by Spreading on Cropland or Pasture

Using manure as a fertilizer by spreading on cropland or pasture may be one option for managing horse manure if you have sufficient land available (see "Do You Have Enough Land?").

Manure contains nitrogen, phosphorus, potassium, sulfur and various micronutrients, which are all required for proper plant growth (Table 7). Horse manure is also high in organic matter, which can enhance soil quality by improving soil structure, increasing water and nutrient-holding capacity and reducing susceptibility to erosion.

Horse manure is an excellent fertilizer for pastures and field crops when applied in the correct amount and at the optimum time (Figure 16). When to apply the manure and how much to apply is depends on several factors:

physical, chemical and biological characteristics of the soil
composition of the manure
the type of crop or pasture where the manure will be spread

Figure 16. Three options to manage the manure on your farm.
Courtesy University of Minnesota Extension Service: www.extension.umn.edu

Do you have enough land?
The amount of land needed to take advantage of the fertilizer value of manure depends on the type of crop or pasture to be grown, targeted yield and soil analyses . For example, the manure produced by one to two horses in one year would be suitable for meeting the nitrogen requirements of approximately one acre of pastureland. Over-application of manure will affect plant growth and increase the risk of water contamination from runoff.

The amount of land needed for manure application can be calculated based on the nutrient composition of the manure and the fertilizer recommendations for the specific crop. For crop-specific fertilizer recommendations, please refer to Alberta Agriculture's website or the Alberta Agriculture publications: Alberta Fertilizer Guide (Agdex 541-1) and Crop Nutrition and Fertilizer Requirements (Agdex 540-1).

Step 1: Sample Your Soil

To take full advantage of any fertilizer, including manure, you should first sample your soil and have it analyzed. A soil test provides the basis for deciding the amount of manure required to correct any physical, chemical or biological deficiency present in the soil.

You can either take the soil samples yourself (see "Soil Sampling Tips") or hire an agricultural consultant who specializes in soil sampling to collect samples for you (Figure 17). The soil must be sampled correctly to obtain useful lab results that will lead to appropriate manure application recommendations.

Soil samples can be tested for the following:

pH (a measure of soil alkalinity or acidity)
organic matter
nitrate-nitrogen, phosphorus, potassium, calcium and magnesium
micronutrients (zinc, copper, iron and manganese)
electrical conductivity (a measure of total salts)
texture (per cent sand, silt and clay)

At the very least, routine soil analysis should include extractable nitrogen, phosphorus and electrical conductivity. The determination of electrical conductivity is particularly important if the land base has a long history of manure application. Additional tests can be performed if soil fertility levels or specific nutrients are a concern.

Results from a soil test are typically in the form of nitrogen (N), phosphate (as P₂O₅), potassium (as K₂O) and lime (to correct soil acidity) and should include fertilizer recommendations.

Figure 17. Soil sampling.

Manure anyone?
If you do not have the land base to make effective use of all the manure and stall waste your horses produce, a neighbor or local farmer may be interested in using the manure for fertilizer on their land. Even though you will not actually be spreading the manure, AOPA regulatation applies to anyone who uses or transfers more than 300 tonnes of manure annually (the amount produced by approximately 35 horses or more). You should keep records of who removes the manure from your farm and how much manure they remove.

Soil Sampling Tips

1. Know your soils

Soil varies by topography (i.e. slope and aspect), the type of vegetation present, past land use, and the type and amount of fertilizer applied in recent years. As a result, the characteristics of the soil may vary greatly, even in the same field. To obtain the most accurate soil profile, a composite number of soil samples should be obtained from each distinct soil region within the field. 2. The 20-to-30 Rule

You should obtain 20 to 30 samples from each different soil type within each field (i.e. collect one batch of soil samples from the hill tops and a separate batch of samples from the base of the hills. When you are collecting the samples, be sure you are collecting them from the same crop cover (i.e. sample the pasture field, and separately sample the hay field.) Samples can be collected using a stainless steel or plastic soil tube or auger, or a clean garden spade. Be careful not to use rusty tools, because the sample may become contaminated with iron. 3. Sample to cultivation depth

Different nutrients are active within different layers of the soil. To obtain a complete nutrient profile, you should collect samples from at least three depths: 0 to 6 inches (0 to 15 cm); 6 to 12 inches (15 to 30 cm) and 12 to 24 inches (30 to 60 cm). You may want to consult with a local soil laboratory or fertilizer company before sampling. 4. Mix similar samples in a plastic pail

Soil samples should be placed in clean plastic pails, according to soil type and sample depth, for mixing. Be sure to mix the soils thoroughly, crushing lumps in the process. Do not use galvanized steel or brass containers, because the sample may become contaminated with iron or zinc, espectively. 5. Package, label and submit

Finding a Laboratory

Finding a laboratory
Local soil testing and manure testing laboratories can be found in the Yellow Pages of your phone book under "Soil Testing," "Analytical Laboratories" or "Environmental Products and Services."

Step 2: Sample the Manure

You also need to sample and analyze the manure you intend to spread on your cropland or pasture. By understanding what nutrients the soil needs and what nutrients are available in the manure, you will be better able to accurately match the manure application to the needs of your pasture plants or field crop.

You should obtain manure samples as close to the intended application time as possible. The composition of manure can change with storage, so analysis just before spreading will yield the most accurate composition of the manure to be applied. Refer to "Manure Sampling Tips" for a detailed outline on how to collect manure samples properly.

Manure samples should be tested for the following:

total nitrogen (N)
total phosphorus (P)
total potassium (K)
ammonium-nitrogen (NH₄+-N)
moisture content

Manure Sampling Tips

1. Obtain a representative sample

Collect manure samples from six to eight different locations throughout the manure stack, using a pitchfork or shovel. Manure should be collected from the center of the stack, as well as near the outside of the pile. If the outer layer of the stack has become dry and hard, remove the crusty surface and sample deeper into the stack. 2. Thoroughly mix the manure samples

Once all the samples have been collected, place the manure on a clean surface for mixing. With a shovel continuously scoop the outside of the pile to the center of the pile to ensure thorough mixing of the samples. Chop the larger manure particles into smaller pieces with a pitchfork or shovel. 3. Collect a minimum of three sub-samples

To collect samples for analysis, place a one-gallon resealable freezer bag, turned inside out, over one hand and grab a handful of manure. With your free hand, turn the freezer bag right side out over the sample. Seal the bag and place it in another freezer bag to prevent leaks. Repeat this process twice more to obtain three representative sub-samples. Properly label each bag and freeze immediately to minimize odors and prevent nutrient loss. 4. The 24-Hour Rule

Manure samples should be sent to a laboratory for analysis as quickly as possible to avoid nutrient loss. Ideally, samples should be analyzed within 24 hours of collection. Keep records
Keep accurate and up-to-date records of manure applications for future crop and pasture planning. Records should include:

all soil and manure test results
amount of manure applied and at what time of year
list of crop and pasture species grown in each field
crop and pasture production in each field
amount of manure sold or given away to others

Step 3: Calculating Manure Application Rates

Applying the correct amount of manure to your pasture or crop is very important. Overapplication of manure can become a pollution hazard if runoff carries excessive nutrients to surface water or if the contaminants leach into ground water. On the other hand, applying an inadequate amount of manure could reduce crop yields or pasture productivity.

Appropriate manure application rates are calculated based on the following:

nutrients needed by the plant for optimum growth
nutrients already in the soil
nutrients available in the manure

Unlike with chemical fertilizers, not all the nutrients in manure are available to plants during the season it is applied. Rather, approximately half the nutrients in manure are available for the first year's crop; the remaining nutrients become available in successive years as the organic matter is broken down by microorganisms in the soil. This "slow release" of nutrients from the breakdown of manure provides fertilizer value over a longer time.

Large amounts of straw or wood bedding may also affect the nutrients available in manure. Bedding materials undergoing decay have a high demand for nitrogen and will compete with plants for the available nitrogen in manure. As a result, plant growth may be depressed unless the crop or pasture is supplemented with a commercial nitrogen fertilizer. Composting the manure before spreading is one way to improve the availability of nitrogen to growing crops (see the chapter "Managing Horse Manure by Composting" in this manual).

Also note that when manure is used to meet the nitrogen requirement of a crop, phosphorus and potassium will generally be over applied. It is important to monitor the soil, through soil testing, for nutrient build-up. One way to avoid over applying phosphorus and potassium is to meet the soil requirements for these nutrients with manure and then top off the nitrogen requirements with chemical fertilizer.

Specific fertilizer recommendations for crops commonly grown in Alberta can be found on the Alberta Agriculture website or in the following Alberta Agriculture publications:

Alberta Fertilizer Guide (Agdex 541-1)
Crop Nutrition and Fertilizer Requirements (Agdex 540-1)

Step 4: Applying Manure to Land

Once you know the amount of manure to apply to your crop or pasture, you need to decide on the time and method of application.

Manure should not be spread on frozen or snow-covered ground. Because the nutrients in manure cannot be incorporated into frozen soil, there is the potential for water contamination by way of surface runoff during snowmelt. Up to one-third of fall and winter-applied nitrogen may be lost due to denitrification, volatilization, leaching and surface runoff during the spring thaw (Figure 18).

If spreading manure on pasture, apply during the growing season (May to September) when grasses are actively growing. Keep in mind that spreading fresh, uncomposted manure on pastures may carry the risk of re-infesting your horse with intestinal parasites (see "Pasture: to spread or not to spread").

Avoid spreading manure over the same area year after year without soil sampling. Over application of manure may adversely affect forage and crop yield, and an accumulation of excess nutrients is a potential water pollution hazard.

Manure is typically spread using a manure spreader (Figure 19). The alternative is quite labor intensive depending on how much manure needs to be spread. Spreading can be done by carrying the manure out to the field with wheelbarrow or truck and then dumping it. Regardless of how the manure is spread, it is important to harrow or cultivate soon after the manure is applied, to break up the clumps and spread the manure uniformly across the field.

If spreading manure on cropland, apply and incorporate the manure into the soil just before seeding. Some crops, such as alfalfa, may benefit from additional applications of manure throughout the growing season.

To avoid contaminating the water supply, manure should be spread at least 100 feet (30 meters) from any surface water or well.

If you do not have the land base that can benefit from the fertilizer value of manure, make arrangements for your manure to be used off your property. Additional chapters in this manual will provide you with alternatives for managing your manure if spreading is not an option.

Figure 18. Denitrification and volatilization are chemical reactions that convert inorganic nitrogen
ions (NO3 - and NH4 +, respectively) to nitrogen gases, which are lost to the atmosphere.
Courtesy University of Minnesota Extension Service: www.extension.umn.edu

Pasture: To Spread or Not to Spread?

Even with a diligent deworming program, manure and stall waste can contain intestinal parasites, eggs and larvae that can live for years. Therefore, spreading raw manure and stall waste directly on a pasture carries the risk of spreading parasites.

Because composting kills parasite eggs and larvae, properly composting the manure before spreading can reduce the potential for recontamination. For more information on composting, see the chapter "Managing Horse Manure by Composting" in this manual.

Alternatively, harrowing the manure in a pasture to break up manure clumps may allow the heat of the sun to penetrate the manure and kill the larvae. However, harrowing is less effective at destroying the parasite cycle. Harrowing should be done only during hot, dry weather and, ideally, horses should be removed from the pasture for two to four weeks after harrowing. Most importantly, if you spread fresh manure on your pastures, have your veterinarian perform routine fecal egg counts as part of your intestinal parasite control program.

Figure 19. A custom spreader being used to spread large amounts of manure.

Spreading Compost

Compost is essentially manure that has been actively managed to enhance the breakdown process. Because composted manure has undergone decomposition, nutrient levels in compost are somewhat different than in raw manure (Table 8).

While compost can provide some fertilizer value, it is best used as a soil amendment to improve the texture of the soil and the soil.s nutrient level and water-holding capacity.

Spreading compost on cropland or pastures has several benefits over spreading manure:

Compost does not clump like raw manure, so it spreads more uniformly.
Compost contains less moisture than raw manure, resulting in a lighter load to haul and spread, making compost more affordable to spread over large areas.
Proper composting destroys weed seeds and kills parasite eggs and larvae present in raw manure, thereby reducing the risk of reinfection.
Compost carries less risk of depleting the soil, crops at all growth stages and pasture plants of nitrogen because the organic material in the manure has already been degraded more completely.

Compost should be spread on pastures during the growing season (May to September) or incorporated into cropland before seeding. Ideally, you should sample your compost and send it to a laboratory for analysis to gain a better understanding of how much compost to apply. Obtaining a representative sample of compost is similar to collecting a sample of manure for analysis (see "Manure Sampling Tips").

Manure and compost carry the risk of polluting water sources when runoff carries away nutrients and organic matter. Similar to manure handling methods, compost should not be spread on frozen ground or snow. In addition, compost should not be spread within 100 feet (30 meters) of surface water.

The Agriculture Operation Practices Act
As of January 1, 2002, amendments to the Agricultural Operation Practices Act (AOPA) brought major changes to livestock management in the province. AOPA is Alberta.s legislation governing new and expanding confined feeding operations (CFO.s) and is administered and enforced by the Natural Resources Conservation Board (NRCB). AOPA also presents management standards for manure storage and handling, nutrient management and record keeping.

The Bottom Line

Horse manure can be a valuable fertilizer if applied at the proper time in the proper amounts.
Start by sampling your soil and manure to determine what nutrients your soil lacks and what level of manure to apply.
To avoid contaminating the water supply, do not spread manure within 30 meters (100 feet) of surface water, and do not spread manure on frozen or snow-covered ground.
If applying to cropland, spread and incorporate manure into the soil just before seeding.
If applying to pasture, spread and harrow manure only during the growing season (May to September), when the grasses can use the nutrients.
Spreading uncomposted manure on pasture carries the risk of contaminating your pastures with weed seeds and exposing your horse to larger intestinal parasite loads.

Manure and Pasture Management for Horse Owners: Managing Manure by Spreading on Cropland or Pasture

Other Documents in the Series