Manure is not only a byproduct for livestock producers, it is also a valuable commodity. When manure applications are carefully planned and timed they can take the place of artificial fertilizers. The value of using manure as an organic fertilizer is no secret. Dairy farmers across the country apply manure to their fields in hopes of utilizing the nitrogen (N), phosphorus (P) and potassium (K) from the manure to improve soil health.
“Depending on state regulations, a farm’s soil types and the composition of the manure, farms can sometimes get enough nutrients from a manure application to last through an entire corn crop,” said Justin Wagler of Nutrient Management Partners.
Wagler and his wife, Sarah, operate a custom application business that covers Indiana, Illinois and Ohio. “When manure is used as fertilizer, it is extremely valuable,” he said. “Farms can hire a custom application system and still spend less than if they applied an artificial fertilizer. And they get the organic value of manure.”
State regulations dictate application details, but a well-executed manure management plan allows any farm to obtain the full value that a crop nutrient manure can provide while protecting water, air quality and staff.
“Although manure management on dairy farms is often associated with regulations and permits, it is important for all farms to utilize manure properly since it is a valuable resource of nutrients and proper manure management helps to protect the environment,” said Tamilee Nennich, a dairy nutrition specialist with Farmo Feeds.
Nennich and Wagler share their expertise on the latest trends in manure application, considerations for on-farm practices that may alter the nutrient content of manure and tips for maintaining application records.
Gone are the days of simply running a spreader across the fields to dispose of manure. As regulations continue to evolve and an emphasis is placed on environmental impacts, science and sophisticated equipment work in tandem to develop specific application rates that can be adjusted to meet varying needs across a field. In tractor mapping, software plots exactly how much manure was applied to a specific spot in the field.
“We create detailed maps for farmers to retain with their records and so they can submit it to the state along with their other required reports. The maps outline the rate manure was applied at specific locations throughout the field,” Wagler said.
The application rates and subsequently the maps can only be generated based on sample results, both manure and soil.
“It’s important to collect representative manure samples and submit the samples to a certified lab to have them analyzed for major crop nutrients, including nitrogen, phosphorus and potassium,” Nennich said.
Many states only require once-a-year manure sampling, but pulling samples more often can create a more accurate picture of the nutrient content. Some factors impact the availability of nutrients in the manure and ultimately how it is applied in the field. Nennich explained that the nutrition of the animal affects the amount of nutrients in manure, particularly regarding phosphorus.
“When cows are overfed phosphorus, it will be excreted and will need to be managed in the manure through proper applications rates,” Nennich said.
Managing a feeding program to reduce as much over-feeding of nutrients as possible is usually more economical for feeding the cows and it can reduce manure application expenses when manure is properly applied.
Wagler finds that in cattle, dairy and beef, the type of bedding also changes nutrient levels and application rates. “Sawdust and straw have more organic matter to begin with than sand,” he said. “If you have clay fields and use sand bedding, the sand in the manure can be good because it can help the soil come around.”
“Some of the farms pull samples in the spring and the fall so they have closer records,” Wagler said.
The results from soil samples are the other piece of the puzzle. State regulations vary as to how often soil samples must be collected and from how many points within the field. Some producers are sampling more often and are using grid sampling rather than random sampling to have a more accurate representation of the soil types across the entire field. Wagler explained that taking one sample from a 100-acre field may not necessarily tell the whole story whereas grid sampling may show where some parts of the field can take more manure than others.
“It’s important to maximize your manure applications and get the most bang for your buck,” he said. “With grid sampling you may actually be able to apply more total gallons even though some areas within the field receive less than others.”
Wagler noted that one of the newest trends in manure application is the use of drag hoses rather than driving tanks or injectors across a field. Compaction from tank spreaders or injectors can reduce crop yields. “Drag hoses help with compaction issues,” he said.
Application timing is ultimately up to the farmer. However, a spring application may be more beneficial than a fall application.
“I’ve had farmers ask me how much nitrogen they’ll lose over the winter if they apply the manure in the fall,” Wagler said. “I estimate they lose nearly half of the nitrogen compared to spring applications.”
Manure that is applied in early September has a good chance of evaporating into the air, running off and more. If that’s what the farmer chooses, Wagler encourages the use of a cover crop over the top of an application to bind the manure to the soil. “When you have bare dirt, you have more problems with nitrogen and phosphorus leeching out of the soil,” he said.
With new technologies available, manure application rates can be adjusted according to soil type, crop yields and soil fertility. The ability to fine-tune application rates is continually improving as new technologies become more affordable.
Before heading out to spread manure, carefully inspect all manure handling and application equipment to make sure it is working properly. Replace or repair anything that needs to be fixed to prevent leaks and spills.
“Calibrate manure application equipment so that you will know how much manure is applied on the available land,” she said.
Study the field and decide where buffers and sensitive areas are within the field. Consider the location of drainage areas and tile lines. Nennich reminds farmers to take into account specific setbacks that need to be followed in your nutrient management plan.
“Visit with neighbors to inform them of expected upcoming application dates and determine if there are days when manure application might be avoided,” she said.
Watch weather forecasts for wind and rain events that may affect application and avoid making an application immediately prior to predicted rainfall events. Manure that is applied to wet, soggy fields is more likely to runoff or be absorbed by the drainage system rather than infiltrating into the soil.
In the field, additional precautions are needed to ensure that the manure isn’t leeching into drainage outlets or nearby water sources. “Every hour we’re checking in and outbound water ditches and testing for nitrogen to minimize what is leeching into the water,” Wagler said.
Injection applications are one alternative that can help minimize runoff and odor. “Injecting manure or incorporating as soon as possible after application will not only help to conserve the valuable nitrogen in the manure, but it helps to reduce the odor as well,” Nennich said.
Wagler agrees that the new injection equipment used for manure applications creates minimal soil disturbance and puts the manure just under the soil surface. This not only helps with nutrient retention and odor reduction, but also helps reduce erosion and runoff.
Regardless of the size of the farm, maintaining records of all manure application activities is critical. Accurate records are one of the best ways to demonstrate that manure is being handled properly on the farm.
Include the application date, the total acreage the manure has been applied to and the field location. List the amount of manure spread on the fields and the source of the manure. Record the actual nitrogen and phosphorus application rates for each field. If you have access to mapping software, include a map of the manure application in your records as well.
“Manure application periods are very important for livestock producers. Proper management and application of manure is essential to maximize the fertilizer value of the manure, meet regulatory requirements, protect the environment and foster good neighborhood relations,” Nennich said.
Because regulations can vary from one state to the next it’s best to check with your state’s department of agriculture, the local cooperative extension office and or the U.S. Department of Agriculture’s Natural Resources Conservation Service (NRCS) for specific guidelines.
To learn more about the latest developments in manure management practices, check with your local Extension agent and the entity that oversees your manure management plan on a state level.