As winter approaches, the challenges associated with cattle manure application become more pronounced. Adopting best practices that maximize nutrient utilization and safeguard water resources is crucial. What follows are critical considerations for cattle manure application in the winter.
Compliance with regulations
Familiarize yourself with and adhere to local regulations governing winter manure application. For example, Iowa prohibits liquid manure application from confinement operations with more than 500 animal units on snow-covered ground from Dec. 21 to April 1 and frozen ground from Feb. 1 to April 1. Most other states will have similar guidance on whether manure application is allowed and, if so, under what conditions. Understanding what your state or province's rules are is critical for compliance.
While solid manure application is not prohibited by Iowa law, careful consideration should be given to minimizing negative impacts on water quality, as the state's waters are protected. For a cattle operation, this means that how the law impacts you is dependent on your operation and the manure management system you use. The law doesn't prohibit manure application if you work with solid manure, like a bedded pack. However, all manure applications must prevent water quality violations. Applying from a deep pit or other liquid or slurry manure system will be restricted if you use a deep pit or other liquid or slurry manure system.
If your facility has an NPDES permit or an NRCS Comprehensive Nutrient Management Plan, check restrictions specific to your operation in these documents. Typically, both will prohibit winter manure application for all types of manure, solid and liquid, in states where frozen or snow-covered ground is typical.
The winter manure application rules have two parts: a date and condition. Both components must be true for liquid and slurry manure application to be prohibited. So while the calendar date of Dec. 21 is quickly approaching, it is unlikely that the ground will be snow-covered (defined as 1 inch of snow or 0.5 inch of ice on the soil surface). As a result, liquid manure application would still be allowed until snow cover occurs.
Winter liquid manure considerations
When considering liquid manure application during the winter, it is essential to acknowledge its higher risk than solid manure. Liquid manure is more susceptible to runoff and nutrient loss, mainly when applied to snow-covered or frozen ground. Liquid manure has a greater tendency to move with surface water flow, leading to a higher risk of contaminating nearby water bodies.
Inject or incorporate liquid manure into the soil whenever possible to increase manure-to-soil contact and reduce the risk of nutrient movement. Good manure-to-soil contact helps lock in nutrients, reduce runoff potential and improve crop availability. Incorporation also minimizes surface exposure, which limits the chances of manure being washed away during snowmelt or rainfall.
Suppose injection or incorporation is not feasible during the winter. In that case, liquid manure application should be considered only when necessary to avoid storage overflow, which can also pose environmental risks. In such cases, ensure that the application is done to protect water quality, such as selecting fields that are relatively flat and away from water bodies and using vegetative buffers to slow any potential runoff.
Ultimately, the key to effective winter manure management lies in good planning. Ensuring adequate manure storage throughout the fall and planning for spring applications are essential to reducing the need for winter applications. By preparing early and having a solid manure management plan, you can minimize the environmental risks associated with liquid manure application during the most vulnerable times of the year.
Winter solid manure considerations
Solid manure, particularly from bedded pack systems, contains fewer soluble nutrients than liquid manure, which reduces the immediate risk of nutrient loss during runoff events. The bedding material, often straw or cornstalks, helps bind nutrients, making them less mobile and less likely to be washed away. Additionally, solid manure lacks the free water in liquid manure, which minimizes the immediate risk of nutrient movement during snowmelt or rain. As a result, solid manure has a lower overall potential for water quality issues, especially when applied during winter. However, even with these advantages, managing manure applications thoughtfully is essential, ensuring that field conditions – such as soil structure and slope – support nutrient retention and reduce the chance of runoff.
Despite the reduced risk, proper manure-to-soil contact is essential to enhance nutrient absorption and prevent loss before the first runoff event. Applying solid manure to fields when the ground is frozen or before snowmelt can still result in nutrient runoff if conditions change rapidly. To mitigate this, applying solid manure in the fall or spring, outside of periods of higher risk, ensures that nutrients remain in the soil and are available for crop uptake. While bedded pack manure has advantages in winter application, proper planning and timing are necessary to avoid potential nutrient losses and to protect water quality.
Understanding snow conditions
Applying manure directly onto snow-covered fields poses a significant risk of nutrient runoff when the snow melts, mainly if melt occurs quickly. Instead, wait to apply until after snowmelt or choose alternative manure management strategies. Applying manure on frozen ground is also discouraged as the frozen surface inhibits absorption, increasing runoff potential.
Timing is critical; if winter manure application is necessary, apply manure when limited snow is present and quick melts aren't expected. Slow melting encourages water infiltration and absorption of manure nutrients into the soil. If using solid manure when snow is present is necessary, choose fields with lesser snow accumulation that are relatively flat. Increase buffer or setback distances around field edges to reduce the risk of nutrient transport from the field.
Thoughtful land use choices
Assessing land use choices is pivotal in winter manure management. Avoid applying manure on steep slopes or areas prone to poor drainage, as these increase the likelihood of runoff. Choose fields with good water-holding capacity to minimize the risk of nutrient loss.
Additionally, consider the implementation of cover crops, which capture excess nutrients and protect the soil from erosion during winter months. Residue cover offers these main benefits – it helps hold the soil in place, slows down runoff, reduces erosion and acts as a filter to help hold dislodged soil and manure particles. However, residue can also capture snowfall and keep it in the field. While it takes approximately 10 inches of snow to make an inch of water, ice-crusted soil water intake is often slow.
Protecting water quality
Prioritize water quality by maintaining setback distances from water bodies and sensitive areas. Implementing vegetative buffers helps prevent nutrient runoff into waterways. Incorporating manure into the soil soon after application is another effective strategy, reducing the risk of surface runoff and enhancing crop nutrient absorption. Where possible, maintain grass or cover crop buffers downslope of manure-applied areas to slow any runoff and ensure solids in the water settle out before trickling away. Leave a setback area around field borders to reduce the risk of manure nutrients leaving the field.
Adopting these best practices for manure application in the winter will enhance nutrient management and protect our water resources. While research has consistently shown greater potential risk of nutrient loss from winter manure application, research studies demonstrate loss is often related to quick snowmelt or rainfall on frozen soils. If you are currently experiencing no snowpack and low chances of rainfall, the late risk of nutrient loss is lessened this year. Stay informed of the forecast and be proactive in changing weather conditions.
