ST. CLOUD, Minn. — For vegetable gardeners who happen to have livestock around, manure and compost can be a valuable part of your soil health and fertility plan. There are differences between manure and compost, as manure is not placed on a pile to allow microorganisms to accelerate the decomposition process. On the other hand, compost is when manure, straw, leaves, and other materials, are placed in a pile and given time to begin the decomposition process. Compost piles create heat, which can kill E.coli that may still be present in manure. Late fall is the best time to apply manure or compost to help your garden for the ensuing year.
When applying manure, it is imperative that it is applied after the garden is done with production for the year. Manure can harbor certain bacteria, like E.coli, that can have some severe food safety implications if one is still picking from the garden. It is recommended that no produce is picked for 2-3 months after manure is applied. For this reason, it makes the most sense to apply manure to a garden after the garden is finished for the year, or early in the spring right after the final snow has taken place.
When determining the fertilizer benefits that manure or compost can provide, there is no quick answer to it. Both sources are highly variable in their nutritional value to an ensuing crop. Factors that determine the nutrient levels present include: the type of animal, amount of straw present, moisture content, and the storage procedure. Manure or compost with a lower moisture content will have higher nutrient contents, and vice versa. Storage times can impact the amount of mobile nutrients, like nitrogen, that will still be present. Composted manure piles can lose 10-50% of their nitrogen during storage.
Rates of manure or compost to apply vary depending on the many of the same factors listed above. Generally, one should apply no more than these amounts of fresh manure per square foot of garden: cattle: 1 lb, horse: 1.25 lbs, sheep or goat: 2/3 lb, and chicken: 1/3 lb.
There are multiple benefits to applying a manure or compost to your garden soil. First, manure, especially types with plenty of straw, can quickly add organic matter to your soil. Increased organic matter can help with soil structure, water permeability, and water holding capacity. Manure and compost provides a slower release of nutrients into the soil and for your plants to use. About half of the manure’s nitrogen will be available for the first year of growth, the rest will slowly be released as the manure degrades and decomposes.
If you want to know if your soil has enough nutrients to support next year’s crop or if your manure will be able to be sufficient fertilizer, a soil test could be an effective option. The Soil Testing Lab at the University of Minnesota can test your soils and help you see where specific nutrients are needed. For more information, visit: http://soiltest.cfans.umn.edu/testing-services/lawn-garden.
— Eric Koehlmoos, University of Minnesota Extension
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