Manure is not a liability but an asset. As livestock and cash grain margins narrow for the foreseeable future, producers should start viewing manure more favorably, according to specialists at Rock River Laboratory.
“To best do this, producers should track exactly how much of this valuable asset is supplied to the crop to account for its tremendous value,” Rock River Laboratory nutrient management specialist Scott Fleming explained.
According to Fleming, livestock owners should pay attention to three key factors that can affect the value gleaned from manure: application rate, analysis and placement.
Application rate. The easiest means to harvest the value of manure requires little more than the manure applicator's time.
“Unfortunately, accurate manure spreader calibration is not implemented on most farms,” Fleming said. “Whether applying liquid manure through a dragline or pen pack solids via a box spreader, the only way to accurately credit manure application is by knowing the application rate."
When applying solid manure, the calibration process is fairly straightforward. “The first step is weighing the application rig to determine the weight of manure hauled, Fleming explained. “Then, calculate the area of manure application in acres.”
He said it is typically easier to calculate the manure rate for most dragline systems versus box spreaders. Custom haulers have a flow meter in their systems that calculates the manure application rate. “Regulations state that flow meters must be calibrated twice per year,” Fleming said. “This allows for a very accurate estimate of manure rates.”
If a flow meter is not used, the same calculation of volume per area can be used to determine the application rate, but it will be calculated in gallons per acre rather than tons.
Analysis. Once the amount of manure to be applied has been established, it is important to determine what is in the manure. “A manure analysis is the best way to determine the fertilizer value of the manure,” Fleming said. “Proper sampling is critical to accurately reflect the true nutrient content of the manure."
When sampling solid manure, use a push-probe, auger or spade to obtain a representative sample from several locations throughout the manure pile or pack, he said, noting that if the manure is being loaded for spreading, a sample can be obtained by subsampling several spreader loads.
“For liquid manure, we recommend thoroughly agitating the contents of the storage facility before sampling,” Fleming said. He added that it’s best to make a composite sample from 5-10 loads. The subsamples should be thoroughly mixed and submitted as one sample.
According to Fleming, submitting a sample to the laboratory is as easy as placing the liquid or solid samples in a pint-size, screw-top plastic container filled to three-quarters capacity and freezing it immediately. Solid samples may also be placed in a high-quality freezer bag, but most laboratories have sample kits available, so check with the laboratory or fertilizer supplier first to order sampling supplies. Then, keep the manure samples frozen until shipped or delivered to the laboratory.
“We advise customers to mail samples early in the week and avoid mailing over holidays and weekends,” Fleming said.
Most standard manure analysis includes moisture, total nitrogen, phosphorus, potassium and sulfur. A comprehensive analysis will likely include the standard analysis specs, plus nitrate, ammonium, organic nitrogen and pH. Fleming explained that “these values are expressed in either pounds per ton or pounds per 1,000 gal. and are multiplied by the application rate to determine the amount of nutrients applied.”
Placement. The key to safe and effective manure application is applying the manure in the right place at the right time. “In many states, there are laws in place stating where and when manure may be applied,” Fleming said. “Even if your operation is not under a nutrient management plan, it is in your best interest to follow these rules.”
The rules he references exist to limit the amount of manure lost to the environment. When nutrients are lost to the environment, they are no longer available to supply nutrients to the crop.
“In general, nutrients should not be applied during high runoff risk periods,” Fleming recommended. “The Upper Midwest’s avoidance window is generally in February and March, when snow is melting and precipitation rates are high.”
Surface water quality management areas should also be spared from winter applications of nutrients. “These are areas within 1,000 ft. of a lake or pond or 300 ft. of a stream,” he explained. “Such areas close to water create a very high risk of runoff directly into the water body.”
Soil type is the final factor to take into account when applying manure. “Soil types that have high permeability or are seasonally wet are best reserved for spring manure application,” Fleming said. “Since these applications occur closer to the crop use timeline, the risk of loss is reduced.”
For more information on recommended application rates and timing, Fleming suggested referring to the nutrient or manure application standards of specific states.
With just a few simple yet effective strategies, livestock producers can make the most of their manure. These fine-tuned approaches to manure application will allow for better use of the valuable fertilizer that is supplied via manure.