Should I top dress with compost or a combo of compost & soil? - Ask Extension
1) two years ago we added 6 yards of compost to our flower beds. You wouldn’t know it now—Where did it all go? (See pics)
2) Would a mix of top s...
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Should I top dress with compost or a combo of compost & soil? #865769
Asked April 24, 2024, 3:50 PM EDT
1) two years ago we added 6 yards of compost to our flower beds. You wouldn’t know it now—Where did it all go? (See pics)
2) Would a mix of top soil & compost last better than plain compost?
3) a horse farm in our area is offering free compost— am I asking for trouble if I were to use that?
Marion County Oregon
Expert Response
Dear Pamela,
Thank you for contacting us about your soil. In answer to your question, compost continues to decompose for up to 5 years after it is applied. Think of it as a process, not a product.
You can add a topsoil/compost mix which will not sink as fast; however, if you are trying to raise the nutritional content of your soil, topsoil will do little or nothing.
Recent research indicates that most gardeners are using too much organic matter in their soil. The 'ideal' soil contains 3 to 5% organic matter. Any more than this will degrade the environment because plants can only use so much nitrogen, and the excess runs off into local waterways.
N is highly mobile in both plants and soil. Our recommendation is to apply up to 1-inch of compost to the surface of your soil each year, preferably in late autumn. Then, and always, cover any exposed earth with 2 to 3 inches of organic mulch. This stops erosion, protects the soil from compaction by weather, and overall improves the texture and nutrient-holding capacity of the soil.
You may notice that I mentioned adding it to the surface. The reason is that any tilling will disrupt the living systems in the soil. In answer to your question, I suggest filling your beds with a good quality soil that has a similar texture to the existing soil. Then begin a routine of applying compost annually and maintaining the mulch layer throughout the year. It is not necessary to remove the mulch when adding compost since it will naturally perk down into the soil with the rain.
With regards to horse manure, proceed with caution. Horse manure in particular contains many unspoiled weed seeds. While it does provide some nutrition, you may be getting more than you hope for.
I hope this information is helpful. Please write again whenever you have a gardening question.
Thank you for contacting us about your soil. In answer to your question, compost continues to decompose for up to 5 years after it is applied. Think of it as a process, not a product.
You can add a topsoil/compost mix which will not sink as fast; however, if you are trying to raise the nutritional content of your soil, topsoil will do little or nothing.
Recent research indicates that most gardeners are using too much organic matter in their soil. The 'ideal' soil contains 3 to 5% organic matter. Any more than this will degrade the environment because plants can only use so much nitrogen, and the excess runs off into local waterways.
N is highly mobile in both plants and soil. Our recommendation is to apply up to 1-inch of compost to the surface of your soil each year, preferably in late autumn. Then, and always, cover any exposed earth with 2 to 3 inches of organic mulch. This stops erosion, protects the soil from compaction by weather, and overall improves the texture and nutrient-holding capacity of the soil.
You may notice that I mentioned adding it to the surface. The reason is that any tilling will disrupt the living systems in the soil. In answer to your question, I suggest filling your beds with a good quality soil that has a similar texture to the existing soil. Then begin a routine of applying compost annually and maintaining the mulch layer throughout the year. It is not necessary to remove the mulch when adding compost since it will naturally perk down into the soil with the rain.
With regards to horse manure, proceed with caution. Horse manure in particular contains many unspoiled weed seeds. While it does provide some nutrition, you may be getting more than you hope for.
I hope this information is helpful. Please write again whenever you have a gardening question.
Thanks so much Lynne— so if I’ve understood you, how does this plan sound:
We’ll add a 1” layer of soil mix?/soil? now, then a deeper layer of organic mulch in the fall.
As far as the organic mulch, what would you recommend? Wood chips? Fir bark?
Also I’ve heard other people recommend putting cardboard down under the mulch for weed suppression. Do you recommend?
Thanks again,
Pam
Dear Pam,
I suggest that you fill your beds with a good quality soil that has a similar texture to the existing soil. Then, add up to an inch of compost or manure each fall.
Any organic material can serve as a mulch. It depends on what you are planting in the bed and your sense of aesthetics. Landscapers' woodchips (but not bark mulch) are excellent for shrubs, trees, and most perennial plantings. However, these are too coarse for use in vegetable beds where seeds will be planted. For these I suggest clean straw because it is easy to move aside while waiting for the seeds to sprout.
Chopped leaves make a good mulch for almost any type of bed, as are lawn clippings. In a pinch, you can use almost anything to cover the soil including old blankets or evergreen boughs (repurpose your Christmas tree). The main purpose of mulch is to keep wind and rain from eroding or compacting the soil.
If this is still not clear, please let me know.
I suggest that you fill your beds with a good quality soil that has a similar texture to the existing soil. Then, add up to an inch of compost or manure each fall.
Any organic material can serve as a mulch. It depends on what you are planting in the bed and your sense of aesthetics. Landscapers' woodchips (but not bark mulch) are excellent for shrubs, trees, and most perennial plantings. However, these are too coarse for use in vegetable beds where seeds will be planted. For these I suggest clean straw because it is easy to move aside while waiting for the seeds to sprout.
Chopped leaves make a good mulch for almost any type of bed, as are lawn clippings. In a pinch, you can use almost anything to cover the soil including old blankets or evergreen boughs (repurpose your Christmas tree). The main purpose of mulch is to keep wind and rain from eroding or compacting the soil.
If this is still not clear, please let me know.
