For many pork producers, manure application follows closely on the heels of the corn and soybean harvest. This year may prove more challenging than most, due to the wet weather and excessive soil moisture, according to Paul Walker, Illinois State University animal science professor.

Walker says a delayed grain harvest means there may be little opportunity to land apply manure before soils freeze in some parts of the country. “Even in those cases where farmers have been able to harvest corn and soybeans, wet soils increase the chances of nutrient leaching and runoff during or after manure application,” he states. Walker provides the following seven management practices to help producers prepare for fall manure application:

1. Review nutrient management plans. To prevent leaching and/or runoff resulting from manure application, lower manure application rates may be warranted. Nutrient leaching may increase when injecting liquid manure and solids runoff may increase when spreading solid manure during episodes of high rainfall. Consequently, additional land may be required for manure application this fall. Using fields with flatter slopes and lower phosphorous index scores may be a good idea. Plan ahead. Manure application may have to wait until emergency application guidelines for frozen ground are applicable.

Review your current nutrient management plan and noted application methods, application rates and fields of choice. They may require revising for this year. Making updates now may save time, energy and costs later.

2. Develop an emergency application plan. The incidence of manure spills increases when the weather is harsh. “Handling manure is bad enough on a sunny, 80-degree day. Near-freezing temperatures, wet weather and muddy conditions increase the chances for something to go wrong,” Walker says. Train employees in manure spill response. Emphasize who to contact, safety issues and what to do when emergencies occur.

3. Take manure samples. If nutrient overload, runoff and/or leachate are potential problems, as this year, it is especially important to know the nitrogen, phosphorus and potassium concentration of the manure. High nutrient loads mean more land area required for application. In a wet year, balancing nutrient application with potential for runoff is more important than normal to prevent environmental contamination. Sampling ahead of land application helps plan which fields can be used.

Sampling during land application or manure agitation may provide more accurate nutrient results for planning future application rates but it will not help plan application rates for this fall. It is important to build a history of nutrient analyses over time for manure sampling to help manage the nutrients in manure for crop production over the years.

Correct sampling technique is most important. A sample that is not representative of the manure volume is of little value. Slurry sampling is best accomplished using a probe of sufficient length to reach to the bottom of the storage tank. Sampling should only take place immediately following agitation and multiple samples from several locations in the pit should be collected and pooled, especially if only one sample will be sent to a laboratory for analysis. For solid manure, several grab samples from several locations in a manure pile both inside and outside of the stack should be collected and pooled.

4. Take soil samples. Soil samples should be taken prior to manure application. If a field has not been sampled recently, then one sample for every 2.5 acres is best. Generally, one sample collected for every 10 acres is adequate for fields that are routinely sampled, Walker says.

5. Calibrate application equipment. “Calibrating manure application equipment takes a little time, but in the long run it will help meet the correct application rate and make better use of manure nutrients,” according to Walker.

To determine how much solid manure a manure spreader applies, Walker suggests laying out a 56-sq. in. sheet of plastic. Spread manure across the plastic sheet at the desired rate of travel and spreader settings. The net weight in pounds collected on the plastic sheet is equivalent to the tons-per-acre application rate. Remember, N, P and K are calculated based on the dry matter weight of the manure – not the wet weight basis -- unless the laboratory has been given directions otherwise.

6. Timing of application. Manure application on dry soil is the best option. Try to apply at least 24 hours before a substantial rainfall to help prevent runoff. Injection of slurry is a necessity, but it requires dryer soil conditions. Surface application of solid manure should be followed by some kind of primary tillage, but even disking in freshly applied manure is more desirable than no tillage at all. Applying manure to snow-covered or frozen ground may not be allowed except under emergency conditions and, Walker says, this looks like it could be one of those years in some states.

7. Consider the neighbors. “Yes, manure does have odor. It is reality. Therefore, inform your neighbors. Let them know about manure application plans. If possible, tell them how long it might take, how you plan to apply the manure, and how long they might expect to smell the manure. Inquire about any outdoor events in the neighborhood, such as weddings, cookouts, etc. and try to avoid those times for application. This will be extremely difficult this fall because we seem to have such small windows of opportunity to land apply manure. Most neighbors will understand. Some won’t, but at least make an effort. It may yield future dividends,” Walker concludes.

See also Nov. Pork magazine feature article, Manure Matters.

Source: Illinois State University