As crop growers evaluate the damage done to your fields and crops by the 2012 drought it’s easy to see first-hand the cracks, or fractures, that have developed. Confronting the damage left behind will be a priority for months to come.

Whether you or someone else uses your hog manure, when it comes to fertilizing fields for next year, there are some new challenges and considerations. While the first thought is to consider the reduced yields and lower nutrient removal from a field, you also need to account for application challenges that the drought caused.

 “When nutrient uptake is reduced there is an opportunity to capture a drought nutrient credit from the stricken crop that may reduce fertilizer need in the year following drought,” says John Lory, associate professor, University of Missouri Extension.

This year, corn and soybean fields have been harvested for grain, baled as forage or silage, grazed as forage or been abandoned with no removal of the crop. “The methods used in managing fields this year will directly affect the amount of fertilizer carryover to the next year,” according to Lory. (Go to http://bit.ly/OMvWRJ.)

Drought nutrient credits can be important, particularly on fields where little or no material was harvested in 2012. Yet other crop removal scenarios may actually increase fertilizer needs next year. “Chopped corn, for example, can increase potash requirements for next year’s crop,” he adds.

There’s also the potential for further nitrogen loss through leaching or denitrification if excessively wet conditions prevail between now and next spring. (For more on estimating next year’s nitrogen requirements, go to http://bit.ly/R29jLP.)

While some producers or applicators till the soil prior to manure application, others may not be able to because of the hard ground. However, always consider possible consequences. “Tilling will seal the soil surface which can lead to surface runoff even under dry conditions, especially if a sprinkler system or a big gun is used,” says Mahdi Al-Kaisi, professor of soil management, Iowa State University.

Be aware that the drought damage in fields may require you to alter your routine as you prepare to apply liquid swine manure to dry fields. Large cracks in crop fields are common this year and create a new set of challenges. Depending on soil type and clay content, deep cracks can open a direct route to drainage pathways beneath the surface, which will require extra caution when applying swine manure to parched fields.

Before application begins, be sure to have a good understanding of field conditions and soil type, Al Kaisi says. “Make sure that your planned application rate will not exceed the soil’s infiltration rate.”

While that’s true regardless of soil moisture conditions, it’s especially important during or following dry conditions. Over-application in dry or wet conditions can create concerns for either surface runoff or deep percolation if the soil is wet. “However, in dry conditions, the soil’s storage capacity is much higher and it can naturally store more moisture than in wet conditions,” Al-Kaisi says. He recommends low rates and gradual application, as that will provide better opportunity for liquid manure to soak in and prevent surface runoff. 

Taking measures to prevent manure from reaching tile outlets is critical, according to Amanda Meddles and Glen Arnold, Ohio State University agronomists. They suggest monitoring tile outlets for manure flow during and after application. Sometimes it can take only seconds for manure to reach tile lines.

If more manure is applied than the soil can hold, there is an increased risk that the manure will move off the field and result in contamination of water bodies. “Injecting on 30-inch centers means that manure is being applied at a much higher volume directly behind the injectors than the soil may be capable of absorbing,” Meddles warns. 

Check during application as well as throughout the next 24 hours, depending on how dry the tile is and how far the outlet is from the site of application, Meddles says.  Tile plugs and control structures can be used to ensure manure does not exit the outlets, or they can be used in an emergency situation to stop manure that’s already flowing. (See sidebar.)

Lory suggests having an assistant on an ATV monitor for runoff during application. “Fields with ground cover and those protected by vegetative buffers will pose less runoff risk,” he says. “However, ground cover and vegetative strips that are drought-stressed will be less protective.”

If injection is not possible, surface application will leave nutrients vulnerable to runoff if initial rains are heavy, Lory says. “A portion of the nitrogen value in manure also will be lost if applied to the surface, due to volatilization.” 

Whether surface applying or injecting this fall, consider using lower application rates. That is just what Troy Goeckner, Effingham County, Ill., pork producer and corn grower, is doing. “The only thing we may be doing differently this year is applying less manure per acre to increase our coverage,” he says. “The short corn crop removes fewer nutrients, and we are able to cover more acres.”    

The impact of the 2012 drought will likely linger for years. Being cautious with manure application this fall will help you prevent yet another possible drought-related problem.

Safety Comes First

Having the proper equipment and tools available should an emergency arise during manure application should be on your to-do list.

“Check your state regulation as well as your operating permit and nutrient management plan,” says Matt Bradshaw, Bradshaw Custom Pumping, Griggsville, Ill. He does custom application and finishes 18,000 hogs annually.

Often regulations in each will limit total one-pass application rates. These are dependent on, but not limited to, soil type, slope and soil conditions. “Before you start, make sure you’re aware of current state regulations as well as the responsible agency and its contact information.”

Bradshaw encourages customers to do some tillage prior to application to fill cracks and ease injectors into the soil. When that’s not possible, he may rely on an Aer-way applicator for less concentrated slurries from lagoons and sow buildings with deep pits.  “This does a good job of evenly incorporating liquid into the top 9 inches of soil. The plow injects every 30 inches, which does increase the possibility of reaching field tiles.”

Bradshaw monitors field tiles continuously during and after manure application and has not encountered problems with leakage into drainage tiles this year.  In the event there is evidence of manure in tile lines, Bradshaw and his crews follow a set protocol:

  1. Stop application in the affected area.
  2. Plug tile line to stop flow. Each crew carries commercial inflatable pipe plugs in case of leaks. (Foam pigs held in with an inflatable kick ball also work and can cut expenses.)
  3. Find how far the liquid has traveled from the end of tile and stop it by damming up the area.
  4. Always have a spill response kit — at least shovels, trash pump and plugs. Clean up affected area. 
  5. If release levels were high enough or liquid reached any surface waters, contact your state agency and file the proper spill reports.

This fall, Bradshaw has adjusted application rates on very dry and hard ground, especially when applying low-percent solid slurries such as lagoon water.  The thinner product does not “stick” and tends to move more readily. However, because it has fewer nutrients, it may require higher application rates to meet crop nitrogen needs.  “In these cases, we decrease application rates to less than one-half inch per acre and make multiple applications.”

Bradshaw avoids applying on fields with fresh tile lines installed within the past year.  “If application is the only option, do not apply until tile lines have had a few inches of rain on them and worked down,” he says. “Then apply a very low rate-- less than one-third of an inch per acre.”