By Erica Rogers and Sarah Fronczak
Proper land application of compost is important for plant uptake and utilizing best management practices for application also improve environmental sustainability and help to maintain positive neighbor relations.
Compost is a mixture of biological materials that are rich in carbon, such as straw and leaves, mixed with 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 to 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, as discussed in part 4 of this series, is critical for suitable land application.
Michigan State University 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 degrees Fahrenheit
- 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 slope of greater than 6% should be avoided when the ground is frozen or snow-covered. Waterlogged fields also have a greater chance of surface runoff and leaching into tile.
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-share for these practices may be available through your local Conservation District. Application should be avoided in areas of the field that routinely flood like 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 of the outlets is clear because color indicates that sediment and associated nutrients are making their way through the tile and into surface waters, thus 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 to which it is applied. It is important to obtain a nutrient analysis of compost and a soil analysis of the field on which the compost will be applied. These analyses guide the operator to apply the correct amount of compost to meet the nutrient needs of the crop. Additionally, the analysis of the soil identifies where there are excess nutrients in the field, so that excess application of nutrients, and therefore loss of nutrients, will be less likely to occur.
Fertilizer recommendations can be found in Tri-State (Michigan, Ohio, and Indiana) recommendations for field crops. Tri-state recommendations now use Mehlich-3 extraction, not Bray P1, as in the past. It is important to refer to your specific soil results as to which test was used. This will help determine the application rate at which you can apply the compost.
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 temperatures of compost as it is being made, requiring the compost to reach a minimum temperature between 130-170 degrees F over several days, depending on the system used.
By following these recommendations for the storage, transfer, and application of compost, you will have more success from an economic, environmental, and social standpoint.
Source : msu.edu