Proper land application of compost is important for plant uptake, and utilizing best management practices for application also improves environmental sustainability and helps maintain positive neighbor relations.
Compost is a mixture of biological materials that are rich in carbon, such as straw and leaves, and biological materials that contain nitrogen and other plant nutrients, such as animal manure and legume plants. This process requires adequate moisture, time and mixture to create a more stable, organic soil input.
Compost does not supply a quick source of nutrients but supplies the soil with organic matter that contains a blend of nutrients, which are gradually available two the crop and add to soil carbon. Applying compost provides crop nutrients and organic matter that help to improve soil quality. Remember that the proper transfer and calibration of equipment is critical for suitable land application.
Michigan State University (MSU) Extension recommends considering the following factors when land applying compost:
• Environmental impact.
• Neighbor relations.
• Crop nutrient utilization.
Both long-term seasonal conditions and short-term weather forecasts must be taken into consideration when land applying compost. The ideal time to apply nutrients to the soil is when crops can maximize uptake, which is in the spring. However, this may not always be practical. In many cases, fall or early winter application occurs. If compost needs to be applied during this time, utilize the following recommendations:
• Apply to medium or fine textured soils.
• Avoid coarse textured soils.
• Wait until soil temperatures are below 50 F.
• Consider establishing cover crops to maximize nutrient uptake.
Precipitation increases the chance of runoff and the potential for nutrients to flow into surface waters. Frozen or snow-covered ground increases the chance of nutrient runoff, especially if the field is sloped. Fields with a slope of greater than 6 percent should be avoided when the ground is frozen or snow-covered. Waterlogged fields also have a greater chance of surface runoff and leaching into tiles.
Ways to help prevent environmental issues include incorporating compost within 48 hours following application to reduce the chance of runoff and loss to tile lines. The way incorporation is done depends on available equipment, the type of cropping system (no-till vs. tillage) and crops planted.
You may want to consider conservation practices such as a vegetative buffer or filter strips to collect soil coming off the field. Cost sharing for these practices may be available through your local conservation district. Application should be avoided in areas of the field that routinely flood, such as wet holes and near surface water.
Many crop fields in Michigan have tile drains installed. These tile drains are a direct conduit to surface waters; therefore, it is critical to locate the tile outlets before application of compost. If the tile outlets have flowing water, application is not recommended because the soil is already saturated. Observing the tiles after application is also important.
There should be no flow from the outlets, but if flow is present after a rain event, check to make sure the water coming from the outlets is clear. Color indicates that sediment and associated nutrients are making their way through the tile and into surface waters, and leaching is occurring.
Just like with the environment, neighbors should also be considered when applying compost. While compost typically has less odor than straight manure, there may still be some odor. To maintain good neighbor relations, some key points may help:
• Avoid application on holidays and weekends.
• Tell your neighbors when you are going to spread compost to keep open communication.
• Avoid application during your neighbors’ big life events, such as reunions, weddings or open houses.
• Utilize vegetative barriers, like trees, that can capture some particles on which odor is carried.
• Spread compost in the morning, as warmer air will then rise throughout the day and carry odors up and away.
• Spread compost during weekdays, as most people are at work or school during this time.
• Where possible, keep hauling and spreading equipment clean.
The last piece to consider is the nutrient utilization of the compost by the crops it is applied to. It is important to obtain a nutrient analysis of compost and a soil analysis of the field where the compost will be applied. These analyses guide the operator to apply the correct amount of compost to meet the nutrient needs of the crops. Additionally, the analysis of the soil identifies where there are excess nutrients in the field, so excess application of nutrients, and therefore loss of nutrients, will be less likely to occur.
Finally, keep updated records for best management. Record items such as soil and compost nutrient analyses, the date and rate of compost application, cropping records, including past yields, etc. A helpful reference record sheet can be found in MSU Extension’s Small Farm Manure Management Planning publication.
All types of farming can benefit from the addition of compost. Certified organic systems require records of not only the above items but also temperatures of the compost as it is being made, requiring the compost to reach a minimum temperature between 130-170 F over several days, depending on the system used. See the USDA compost tipsheet for additional information.
By following these recommendations for the storage, transfer and application of compost, you will have more success from an economic, environmental and social standpoint. — MSU Extension
