The feedlot and manure management
By using the best manure management practices, the field application of manure produced in the feedlot can enhance soil productivity and contribute to overall farm profitability while maintaining proper environmental stewardship.
As a byproduct of raising livestock, “shit happens” literally, and that is no different in a beef feedlot setting. Therefore, as the producer, we must carefully decide how to remove and utilize the manure produced from the cattle in the feedlot. By using the best manure management practices, the field application of manure produced in the feedlot can enhance soil productivity and contribute to overall farm profitability while maintaining proper environmental stewardship to prevent water contamination.
The first step to successful manure management is to determine the Nitrogen (N), Phosphorus (P), and Potassium (K) levels of the manure being produced and of the soil in the fields. The level of these nutrients excreted in the manure can be impacted by the diets being consumed by feedlot cattle. For instance, some by-product feeds have a slightly greater P content and a greater inclusion of them in the diet could cause manure to have a greater P concentration. Likewise, higher protein diets or diets that supply excess protein can lead to greater N excretion, and therefore, a greater N concentration of manure. At the 2009 Cattle Feeder’s Conference: A New Era of Management, Russ Eken, an extension livestock specialist, reported that backgrounding and finishing cattle have been reported to excrete 6.3 lb. of manure per 100 lb. body weight, 0.22 to 0.48 lb. of N, and 0.035 to 0.085 lb. of P per head per day.
Other factors such as feedlot design, stocking density, time of year, and method of manure storage can influence the moisture and nutrient composition of manure. Eken also reported that on a dry matter basis, N, P, and K concentrations of manure from open earthen lots (1.64, 1.19, and 1.04%) and bedded confinement (3.08, 1.67, 2.00%) facilities are less and more variable when compared with deep pitted manure storage (20.0, 12.5, 17.5%;). Manure nutrient composition from open earthen lots is likely to be influenced by the amount of dirt collected when scraping. While manure accumulation from bedded confinement barns will likely be greater due to the inclusion of bedding. According to Applied Engineering in Agriculture, manure from open lots will be dryer (33% moisture) due to a greater pen surface area and lesser stocking density compared with bedded confinement (70% moisture) and deep pit manure (90% moisture); especially during the summer and fall months as compared with the winter and spring months. Manure from open earthen and concrete lots, as well as bedded confinement facilities will lose more N due to the volatilization of ammonium (inorganic N) into ammonia gas compared with deep manure pits. According to the Nebraska Beef Cattle Reports, increasing the frequency of cleaning pens monthly compared with at the end of the feeding period can reduce the loss of N from volatilization by 12.5 to 15.0%. Storage of freshly scraped manure can also be stockpiled or composted when weather conditions are not favorable for spreading manure on fields due to run-off or compaction concerns.
The business management saying, “You can’t manage what you [don’t] measure,” also applies to smart manure management. Get into the habit of recording manure and fertilizer application dates and rates. Keep a record of manure and soil nutrient analyses to track changes in nutrient composition of the manure being produced and field/crop nutrient usage. Past field crop yields are also very useful when it comes to predicting the proper manure application rate for your fields. Knowing the total amount of manure produced, the nutrient concentration of the manure, and the nutrient requirements of the crop at an expected yield can allow you to determine the appropriate manure application rate for the field. Diligent record keeping of your manure management practices allows for better manure management decisions to be made and increase the farm’s profitability.
The weather and soil conditions greatly dictate the timing for proper manure application practices to prevent water contamination. Michigan State University (MSU) has partnered in developing the Michigan EnviroImpact tool, which provides a short-term daily forecast for nutrient run-off risk across Michigan. The Michigan EnviroImpact tool factors in precipitation, soil moisture and temperature, and landscape topography to assess the risk of nutrient run-off. Use of the Michigan EnviroImpact tool can be an extremely valuable resource to determine proper timing of manure application due to variable weather events with possible email and text alerts. In addition to the weather and soil conditions, it is also very important to be aware of nearby water bodies, wells, and tile lines, so you can maintain an adequate distance away when applying manure to prevent water contamination. Consult with your local MAEAP technician to determine the appropriate distance away from water resources before applying manure.
It is also important to consider manure application methods and the use of cover crops to improve manure nutrient efficiency, soil composition, and reduce nutrient run-off. In a 2010 article “Nutrient transport in runoff as affected by diet, tillage, and manure application rate”, by Transactions of the ASABE, reported incorporating or injecting manure into the soil versus only surface broadcasting manure has been found to reduce the loss of the manure N applied due to volatilization during manure application. Tilling fields after broadcasting manure can also result in a lesser total P concentration in run-off but results in a greater NO3 concentration in run-off collections compared with no-tilling after manure application. Cover crops offer protection from nutrient run-off after manure has been applied to fields and can be harvested or grazed as a feedstuff. The roots of cover crops help to bind field soil to prevent erosion and prevent nutrient leaching from the soil. According to a 1998 article “Cover crop impacts on watershed hydrology” by the Journal of Soil and Water Conservation, cover crops allow for greater water infiltration to help reduce water run-off and increase the water storage capacity of the soil (Dabney, 1998).
If you are interested in additional information regarding the best management practices for manure management application, consider completing the online Michigan Manure Hauler Certification Program.
This article originally appeared in the Michigan Cattleman’s Magazine.