Revised:  09/14/2012

Ask the Expert -- Farm and Pasture Management













Farm and Pasture Management

Fertilizers and Herbicides



How do I get rid of alsike clover in my pasture?



I want to spray and fertilize my pasture, but I have a problem with alsike clover. Can you tell me what herbicide I should use to get rid of it?



Alsike clover in your pasture can be treated much the same as other broad leaf weeds. There are products such as Banvel, Cimarron, and Milestone that can be used, but it is recommended to follow the recommendation on the label of the herbicide or check with your local extension office before considering what one to use. A recommendation for herbicides in New Jersey may not be appropriate for other states. Some herbicides approved for use here may not be approved in your area. Also, there could be differences in production practices that may need to be considered. Also be aware that most herbicides that will kill alsike clover will kill all other clovers.


Answer provided by Bill Bamka, Rutgers Cooperative Extension, Burlington County Associate Professor/County Agriculture Agent, Field and Forage Crops.



Which fertilizer is better – ammonium nitrate or ammonium sulfate?


I plan to fertilize my pastures soon. I am trying to decide between ammonium nitrate and ammonium sulfate. I have calculated that ammonium nitrate is 35 % nitrogen and ammonium sulfate is 21% nitrogen. Other than cost per pound of nitrogen, is there any other reason to choose one over the other?



Ammonium nitrate has a nitrogen/phosphorous/potassium (or N-P-K) ratio of 33-0-0 and ammonium sulfate is 21-0-0. Since pastures should receive 50 pounds of nitrogen per acre at green-up in spring, you will need to apply approximately 175 pounds of ammonium nitrate per acre and 250 pounds of ammonium sulfate per acre. Ammonium sulfate supplies a small amount of sulfur to the soil, which may or may not be deficient in your soils. All nitrogen fertilizers will increase soil acidity and ammonium sulfate has a slightly higher acidity equivalent than ammonium nitrate. You should be sure to maintain your soil pH above 6.5. Urea (46-0-0) is another option for pasture fertilizer use. Urea is unstable and will volatilize fairly quickly. You should only use urea if the weather forecast calls for rain in the near future.


Answer provided by Donna Foulk, former Senior Agriculture Program Coordinator, Rutgers Cooperative Extension.



How do I get rid of brome grass?


I am trying to get rid of the brome grass that is growing in a meadow next to my house. I want to plant all red fescue. How do I get rid of the brome and turn it into fescue.



Removing one species of grass selectively from a grass mixture can be extremely challenging. An herbicide that is selective for grass control will likely kill the brome grass as well as any other desirable grasses in the meadow. Therefore planting will likely require a complete renovation. This can include plowing, disking the ground and preparing the ground for planting. Another alternative would be to kill all the vegetation with a non-selective herbicide such as glyphosate and no-till the fescue into the meadow. A word of caution regarding the fescue you choose - make sure it is a grazing type fescue that is free from endophytes. Many turf varieties of fescue contain endophytes.


Answer provided by Bill Bamka, Rutgers Cooperative Extension, Burlington County Associate Professor/County Agriculture Agent, Field and Forage Crops.



How do I control Cheat and Downey Brome in a hay field?


I purchased a small 6 acre horse farm. On two of the acres I am growing hay for my farm. My two horses graze on almost 3 acres. The problem this year seems to be that one half of the hay field is covered with Downey Brome or Cheatgrass. This weed seems to be concentrated on one side. Last August I sprayed a weed killer over the field to try and kill the broadleaf weeds. In mid September I harrowed the field and overseeded it with Orchardgrass. This spring, all this Cheatgrass popped up.


What are your recommendations? Should I just kill off the entire 2 acres, till the soil and plant a new field of Orchardgrass? Or is there a simpler way to rid my field of this weed?


Unfortunately, there are no herbicide products that are labeled for Cheat or Downey Brome. Cheat is a winter annual grass, so control would have to be on a pre-emergent basis, and unfortunately we have no herbicides labeled for hay or pasture that fit that situation.


Controlling a grass weed in a grass pasture is an extremely difficult situation. Plowing up the field and restarting will offer some challenges also, I am afraid. It is my guess that you have a seed base within the soil, so there is a possibility of the Cheat becoming re-established. If you think the stand needs to be re-established, you will want to do everything you can to insure a healthy and vigorous stand of orchard grass, so that the orchard grass out-competes the Cheat. I would suggest taking a soil test to ensure that the soil pH of the field and the nutrients in the soil are in the optimum range. I would start out with a vigorous, quality seed, and make sure the seed bed is adequately prepared for forage seed establishment.


Answer provided by Bill Bamka, Rutgers Cooperative Extension, Burlington County Associate Professor/County Agriculture Agent, Field and Forage Crops.



How much water do I mix with my fertilizer?


I am in the process of fertilizing my hay field. My soil test results say I need to apply 50 lbs of nitrogen per acre. I have a 100 gal sprayer and I have Ammonium Nitrate in 50 lb bags. I need help knowing how much water to mix per lbs of fertilizer?



When trying to make a fertilizer solution from a granular fertilizer it is important not to exceed the solubility of the fertilizer. You want to avoid materials that do not dissolve into the solution. Ammonium nitrate fertilizer has a solubility of 984 pounds per 100 gallons of water. This results in about 3.3 pounds of nitrogen per gallon. This would require about 15 gallons of material per acre to get 50 pounds of nitrogen per acre. However, I am afraid that applying that much material per acre will likely result in burning and possibly killing the vegetation. The material would best be applied as a granular broadcast across the pasture. If you really want to apply a liquid you could mix a test batch and apply it to a small area of the pasture to see if vegetative burn does occur.


Answer provided by Bill Bamka, Rutgers Cooperative Extension, Burlington County Associate Professor/County Agriculture Agent, Field and Forage Crops.



When fertilizing a pasture, what kind of fertilizer should be used and how often?


I have a small farm with approximately 5 acres of grazing pasture. The pastures are a mix with clover. Is there an all-purpose liquid fertilizer product(s) that you would recommend that will not break the bank? And how often do I need to fertilize?



The best way to find out how much fertilizer your pastures need is to take a soil test. Your grasses, just like your horses, need certain nutrients (such as nitrogen, phosphorus and potassium) to keep them healthy and the only way to know what may be missing in your soil is to get it tested. It is a simple and inexpensive process which may actually save money that might have been spent on unnecessary fertilizer. Go to the Rutgers Soil Testing lab website for instructions on how to take a soil test and where to send it. If you are not in New Jersey you can do an on-line search for your state’s Cooperative Extension Service soil testing lab.


You can also go to our website and read other answers to questions regarding fertilizing pastures.


Answer provided by Carey Williams, Ph.D., Rutgers Cooperative Extension.



Will horses founder on freshly-fertilized pasture?


I was going to fertilize and lime our 6-acre horse pasture, but was advised by a friend not to, as there have been cases of founder linked to over-fertilization and nitrogen left in the soil. I lost a horse last summer to a mysterious case of founder a few months after my pastures were treated. Are the two events related?



Fertilizing and liming pastures is a very important component of pasture management. There is no risk to horses as long as the correct protocol is followed as outlined below:


Soil Testing Pastures
It is always advisable to conduct a soil test on pastures before applying fertilizer so that you are only applying nutrients that are necessary for the forage in your particular pastures. A soil test kit can be obtained from your local Cooperative Extension office.


Liming Pastures
Pastures can be limed with ordinary limestone without removing the horses from the pasture. It may be advisable to remove horses from limed pastures until rain has removed the limestone "dust" from the forage leaves, but agricultural lime has no toxic properties.


Fertilizing Pastures
Horses should be removed from pastures when fertilizer is being applied to the pastures. Nitrogen (N) fertilizer is toxic and horses should not be allowed to graze pastures until rain has completely removed all of the fertilizer from the leaf surfaces and carried it into the soil. Ammonium-based nitrogen fertilizers bind to soil particles but are quickly (within 2-3 days) converted to nitrate nitrogen when the soil is warmer than 50 degrees. Nitrate nitrogen is quickly leached from soil. Generally it takes about ½ inch of rainfall to dissolve the fertilizer. Therefore, as a general rule of thumb, horses should be removed from fertilized pastures and not returned until at least ½ inch of rainfall has occurred and the fertilizer is no longer visible on the soil surface. Best management practices dictate that after fertilizing pastures, horses should not be returned to the pastures for 2-3 weeks in order to provide ample time for the pasture grasses to grow and recover from grazing.


Sources of nitrogen fertilizer
Pastures should receive an application of 50 lbs. of nitrogen per acre in spring and late summer. There are many different chemical and physical forms of nitrogen fertilizer. The nitrogen in urea (46-0-0) is completely water soluble and is readily available to plants upon application to the soil. If ½ inch of rain does not fall after application, significant loss of nitrogen will occur from volatilization. Therefore, urea should be used only if rainfall is imminent.


Other sources of nitrogen, including ammonium nitrate and ammonium sulfate as well as complete fertilizers such as 10-10-10 or triple 15 are not subject to volatilization and will remain on the soil surface until rainfall leaches the fertilizer into the ground.


A note of caution: Turf -type fertilizers should not be used for horse pastures since the nitrogen is specially formulated so that it is released very slowly. Slow release fertilizers can exist on the soil surface for several weeks.


As far as laminitis being caused by fertilizers, there is no evidence that pasture grasses that are fertilized correctly cause laminitis. It is important to introduce horses to new pasture slowly since any abrupt change in diet can trigger digestive problems that can result in laminitis. If your horse has foundered in the past, you may want to restrict access to pastures. Two periods of time to be especially careful in grazing laminitis-prone horses are in spring and fall. If you think back to your biology classes, you will recall that grasses produce sugar through photosynthesis during the day. At night plants use up some of the sugar through respiration. It has long been known that the sugar content of pasture grasses is higher in the afternoon than in the morning. If nighttime temperatures in spring and fall drop below 45 degrees, respiration slows or stops and the sugar remains in the grasses. Fairly high sugar contents can occur in cool season grasses if several cold nights occur in succession and are followed by bright sunny days. This is a normal process that does not affect most horses. However, there is some discussion and research occurring at present to determine whether the high sugar concentration in pasture grasses caused under specific environmental conditions can contribute to laminitis in horses that are predisposed to metabolic problems.


Answer provided by Donna Foulk, former Senior Agriculture Program Coordinator, Rutgers Cooperative Extension.



Is there a grazing-safe herbicide to use on horse pastures?


Are there any liquid herbicides available (natural or chemical) that can be applied to pastures without having to keep horses off of the pasture until it rains significantly (1 inch)? Any advice would be appreciated.





Yes, there are herbicides you can use on horse pastures that do not require a long grazing restriction (see first 2 links below). However, it is most important to select an herbicide based on the type of weed you are trying to control. Some herbicides have greater efficacy on certain weeds, and do not control other weeds at all. For information about this, contact your Cooperative Extension county agricultural agent for weed identification and recommendations for your specific situation. Remember that some of the herbicides listed are restricted use and must be applied by a licensed applicator. It is also important to note that on pastures, regular mowing can be a very effective form of weed control. Mow weeds before they go to seed and many will die out, while grasses will thrive with the extra mowing. However, you do need a good stand of grass to replace the weeds, so make sure your pastures are healthy and soils are tested and limed/fertilized according to the soil test results. Good, lasting weed control is a matter of maintaining pastures so that the grasses out compete the weeds. Otherwise you will find yourself spraying frequently.


Rutgers Fact Sheet

Grazing Restrictions for Pasture Herbicides


Penn State Extension

Grazing and haying restrictions for grass forage and pasture herbicides

Finding your county Cooperative Extension Agricultural Agent


Rutgers Fact Sheet

Establishing and Managing Horse Pasture

Equine Pasture Management “A Year-Round Approach”




What herbicides can I use on a horse pasture?


Are there any safe weed killers that can be used on horse paddocks? I dig out as many weeds as I can in early spring but they never go away.



There are many weed control products that are safe for use in a pasture when applied according to the label instructions. The first step in determining which herbicide to use is to first properly identify the weed species you are trying to control. Once you know what weed species you are trying to control you can develop a control strategy. For instance, you need to know whether you are trying to control winter annual or summer annual weeds, or perhaps a perennial weed. The time to apply herbicides for effective control is different for each of these weed types. Also, herbicides vary in their effectiveness in controlling individual weed species. Most pasture owners in our area are looking to control broadleaf weeds; however, you should contact your Cooperative Extension Agent for help in identifying the weeds in your area. Just remember to follow all the instructions and grazing restrictions listed on the herbicide label.


Answer provided by Bill Bamka, Rutgers Cooperative Extension, Burlington County Associate Professor/County Agriculture Agent, Field and Forage Crops.




Should we still lime and fertilize our pastures when our horses don’t need the grass?


I have two very easy keeping horses, on the chunky side housed on four acres. I feed them very little when the pasture is good. They are in a turnout shed and have 24 hour access to the pasture. My husband is not happy with the amount of weeds and bare spots we have this year in the pasture and after doing a soil test we found out the pH is very low (5.3). Should we spend the time and money applying lime and nitrogen when my horses really don't need a lush pasture?




It sounds like your pastures are in need of some care. For several reasons outlined below, we do believe that it is worthwhile to invest in improving your pastures. It is recommended to apply lime and nutrients as shown in the soil test. Fixing the soil’s pH and nutrient levels encourages grass growth rather than weed growth; many weeds thrive in poor soil conditions. It would also be wise to eradicate the weeds because certain common weeds can be toxic to horses. See this fact sheet for more information on toxic plants: Maintaining a healthy stand of grass is also environmentally friendly, because when your horses defecate and urinate in the pasture, they are depositing nutrients that can flow off your farm in rainwater and potentially contaminate local water bodies. Having a well-vegetated pasture, or even a vegetated buffer strip around your pasture, allows the plant roots to take up the nutrients deposited by your horses before reaching waterways. In terms of your horses, many easy keepers benefit from a grazing muzzle for at least part of the day, which allows them to drink water and perform normal grazing behavior, while not actually consuming enough grass to put on weight. When horses eat overgrazed pastures, they prefer the very short young grasses because they contain the most sugar. Especially for an overweight horse, this is not ideal. Allowing the grass to mature before letting your horses graze will increase the fiber content of the grass, making it more appropriate for your horses to eat if they are easy keepers. When implementing new feeding management practices, you should use a weight tape and/or body condition score your horses every few weeks to monitor for weight loss or gain. It sounds like this setup could benefit from a rotational grazing system. Briefly, you would establish a “sacrifice lot” with the shed and water that horses can access at all times, and you would not try to grow grass there. Then you could split the remaining acres into two or three smaller lots and give them access to one at a time. This way, you can control your horses’ pasture access without stalling them, plus you will improve the grass stand by letting it rest for a few weeks (approx. 21 days) after being grazed. Once horses have grazed down one smaller section, you move them into the next section and allow the first to regrow. You can also remove the horses from pasture when it is too wet or frozen so that they do not damage the plants. Many farm owners use lower-cost electric tape to section off larger pastures. The “Establishing and Managing Horse Pastures” fact sheet contains more information on best pasture management practices and rotational grazing.



How long do I need to keep horses off of a newly-fertilized pasture?


I have 3 horses on my pasture. I want to spray a liquid fertilizer on the pasture. How long do I need to keep the horses off the grass after I apply the fertilizer?



Horses should be removed from pastures when nitrogen based fertilizers are being applied and should not be returned to the pastures until adequate rainfall has removed the fertilizer from plant tissues and leached all nitrogen from the soil surface into the ground. Generally, approximately ½ inch of rainfall is sufficient to dissolve granular nitrogen; less is needed when the fertilizer is in liquid form. Under ideal circumstances, it is best to leave the horses off of the pastures for at least 2 - 3 weeks after fertilizing the grasses to allow time for the grass to regrow.


Liquid fertilizers are becoming increasingly popular. The major disadvantage when comparing liquid fertilizers to dry formulations is that they are generally higher in price and usually have a lower analysis. Remember that when making calculations of liquid fertilizer, the analysis is given on a weight percentage, NOT on a volume or "per-gallon" basis. Most fluids weigh between 10 and 12 pounds per gallon. As an example, if you choose a liquid fertilizer with a 10-34-0 analysis that weighs 11.4 pounds per gallon, the gallon will contain only 1.14 pounds of nitrogen (11.4 x .10) and 3.87 pounds of phosphorus (11.4 x .34). Approximately 48 gallons of this liquid fertilizer would be needed per acre to supply the 50 pounds of nitrogen that is recommended for spring applications to pasture grasses. Depending on the productivity of your pastures and your grass species, additional nitrogen applications should be considered in early and late summer. Conducting a soil test will allow you to determine if you need to add lime to maintain proper pH conditions or add any potassium or phosphorus to your pastures.


Answer provided by Donna Foulk, former Senior Agriculture Program Coordinator, Rutgers Cooperative Extension.




Is there a lawn fertilizer that is safe for horses?

I was wondering if you could recommend a commercial fertilizer for that includes an agent for weed and crabgrass control that would be safe for horses. This would be for my home lawn. Although our horse lives on a nearby farm, he is brought to the house on occasion to graze.



No fertilizers or weed control products that are labeled for lawn use should be used on grasses that are used for grazing. They are not labeled for pasture use and it is illegal to use these products on pastures or lawns that are used for grazing.


Lawn fertilizers are frequently time-released products. The nitrogen is often encapsulated to allow a slow release of fertilizer. Slow release nitrogen fertilizers can remain in the soil for many weeks. Nitrogen is toxic and horses should not graze in areas that have received fertilizers marketed for lawns.


Lawn weed control products also cannot be used on grasses that are being grazed either. The products have not been subjected to the rigorous testing that is required when the products are used for pastures.


If you truly need to graze your lawn, then you should manage it as a pasture and only use agricultural fertilizers and herbicides that are labeled for pasture use.


Answer provided by Donna Foulk, former Senior Agriculture Program Coordinator, Rutgers Cooperative Extension.




How can I get a pesticide applicator's license so I can spray my pastures?

How can I go about obtaining certification to spray a restricted herbicide? I have horrible "prickler" stems/bushes that are overtaking both my pastures. My Co-op sells different types of herbicides; however, the restricted one is supposed to really get those bushes under control. I have been trying to find out where I can get the appropriate training with no success. Could you help please?



It is essential to know exactly what weed this "prickler” bush is before you spray anything. A given herbicide will vary in its effectiveness on different weeds. The type at your Co-op may not be the appropriate herbicide for this specific weed. Get a positive identification on the weed first, and then find out which herbicides are most effective. Your local county Cooperative Extension agricultural agent can help determine the best herbicide for your pasture.


In most (if not all) states, pesticide applicators must be licensed. Pesticide is a broad term which includes herbicides, insecticides, fungicides, etc. In New Jersey, one must take an exam administered by the Department of Environmental Protection- Pesticide Control Program to obtain a license, which is valid for five years. Training manuals can be purchased from your county Cooperative Extension office. One may either attend courses and workshops throughout the five-year period to accumulate a certain number of recertification credits. This enables an individual to maintain a valid license status. Another method would be to simply retake the exam at the end of the five-year period. If one does not intend to spray pesticides regularly, it may be more time and cost effective to hire a licensed pesticide applicator for a one-time application for the "prickler" bushes. Commercial applicators for hire have more extensive licensing requirements.


Check with your state’s Department of Agriculture; it should have the pesticide applicator guidelines listed online. Another option would be to contact the Cooperative Extension office in your county. County agents should be able to answer questions and offer guidance and suggestions on procuring the services of licensed commercial applicators.




How do I apply urea on pastures?

I broadcast granulated urea 46 % on our nitrogen-depleted horse pasture (150 pounds per acre as advised by a fertilizer expert) about 12 days ago. We had about a 1/4" to 1/2" of rain that night and then a solid week of warm (upper 70's) sunny weather. We only just got more rain yesterday and today. I was looking out over our pasture today to see how well the grass was coming in and was a little shocked to see that the grass appears to be burned in areas, turning or already turned gold. Did I make a mistake somewhere in the process of spreading the urea? Are there any steps I can take to prevent further burning?



All nitrogen fertilizer materials are salts and have the potential to burn grasses. Urea is an unstable form of nitrogen. The nitrogen in urea quickly hydrolyzes to ammonium and will volatilize into the air and be lost until at least 1/2 inch of rain falls. The conditions for your application sound ideal, since you received rain immediately after the application.


Because all of the nitrogen in urea is in the ammonium form, it has the potential to temporarily "burn" grass. Spring nitrogen recommendations for pastures are normally 50 pounds of nitrogen per acre - so 100 pounds of urea should be sufficient. Higher rates increase the chance of burning the grasses. The effects are temporary, and with repeated rainfalls, the grass should recover and start to benefit form the nitrogen that was applied.


Answer provided by Donna Foulk, former Senior Agriculture Program Coordinator, Rutgers Cooperative Extension.



Can I use vinegar to kill grass growing in my riding ring?

I have grass growing in my sand and stone dust ring. These paddocks and ring have not had a problem in the 18 years that they have been there. I have been told I can use a home remedy of two cups vinegar, 1 tablespoon of liquid soap and 1 tablespoon of salt and that should kill any vegetation.    Do you think this will work? If not what other methods should I try?



As a University program, we cannot recommend the use of “home remedies” which are not scientifically tested for safety and effectiveness, especially around horses. However, after a bit of research on using vinegar as an herbicide, I have come across some University-published information that would be useful. Kitchen vinegar is a solution of 5% acetic acid and 95% water and other compounds. This solution is too weak to control mature plants; it may injure very young seedlings. However, it does not go through the plant, so it only injures above ground parts of the plant and has no effect on the roots. This means that the plant may regrow. You can find stronger acetic acid solutions, but since they are highly acidic, they are corrosive and dangerous to handle. It is recommended to find a commercial product that has been tested and approved for this purpose. There are a few commercial herbicides out there that contain acetic acid. See the links below for University-published information on using acetic acid as an herbicide. As you may be aware, one product that is very effective at killing all vegetation that it touches is glyphosate. This will quickly take care of your weed problem and it does not persist in the soil. Whatever you choose to use, make sure you read and follow label directions carefully. With any pesticide, the label is the law.


Oregon Department of Agriculture

“Fact Sheet for Vinegar/Acetic Acid Recommendations.”


University of Illinois Extension

“Using Vinegar as a Herbicide.”




The material provided on this site is for educational purposes only and is not intended to diagnose, prevent, or treat any illness. Any recommendations are not intended to replace the advice of your veterinarian. Any products mentioned are not intended to diagnose, treat, cure, or prevent disease. Mention or display of a trademark, proprietary product, or firm in text or figures does not constitute an endorsement by the Equine Science Center or Rutgers University and does not imply approval to the exclusion of other suitable products or firms.







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