Raised Bed Vegetable Bed Prep - Ask Extension
We have a large topsoil pile with the nutrient levels shown below. Starting with this topsoil pile, what material should we mix in and in what proport...
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Raised Bed Vegetable Bed Prep #865561
Asked April 23, 2024, 10:31 AM EDT
We have a large topsoil pile with the nutrient levels shown below. Starting with this topsoil pile, what material should we mix in and in what proportions to prepare the soil for filling 12 Large raised bed gardens? We will be growing vegetables in these gardens.
"Vegetable Garden" Soil Test Report "GARDEN" (Apr 23, 2024, #KCYM58)
Phosphorus (P) 19 ppm Below Optimum
Potassium (K) 56 ppm Below Optimum
Magnesium (Mg) 155 ppm Optimum
Calcium (Ca) 900 ppm
CEC 5.9 meq/100 g
Soil Type Mineral *For more information on each individual nutrient, or the bar graph, click on the underlined word.
Soil pH 6.8
Lime Index 72
Organic Matter 2.3 %
Organic matter in your soil is 2.3%. Your soil is low in organic matter and you may consider adding organic matter to your soil by incorporating garden beds with a locally available compost material.
Emmet County Michigan
Expert Response
HI Bill, thanks for your inquiry. A big question re your raised beds. will they have a bottom that does not allow roots to penetrate the natural soil? if this is so you must feed and water on a more frequent basis. Your topsoil mix that you had tested appears to be a good balance and the OM is 2.3% which is not bad. But you can add compost at planting/transplanting time ( a handful into each hole for transplants and a 1/2 along row trenches before planting seeds). Purchase a compost that is labeled or one that you know was processed correctly (turned, heated and allowed to age) to reduce the addition of weed seed. Also know that different plants (vegetables?) have different levels of Nitrogen needs (and the other 2 primary plant nutrients-potassium and phosphorous). But each year checking the pH is a good approach to make sure the compost is allowed to do its job as well as possible. This is also true for any other soil inputs (fertilizers, vermicompost, fish emulsion-all good nutrient suppliers). Just read labels of any product you buy to check the nutrient % so you know what you are adding and account for this. Dont put manure in the garden when there are plants growing as that poses a food safety risk and fresh/raw manure can burn plants due to the high nitrogen. If you use raw manure add it after the season so it breaks down and the nitrogen is available to the crops. This is also a good time to plant a cover crop to over winter, like cereal rye (can buy from any farm store in the fall). Be sure its cereal rye and not ryegrass.Please reach out if you have other questions.
Thank you for your response. Our raised bed gardens will be 24” deep and not have a bottom. There is no soil in them today. The previous sample tested was from a topsoil pile that we intend to use as a base mix for filling the raised beds. So, we have the possibility of adding organic material, vermiculite, compost, worm castings, etc. by mixing into the soil pile before filling rather than composting around each plant or seed. We do not intend to plant until next Spring. Do you have any fertilizer and product recommendations and/or proportions for how to make this raised bed mix utilizing the soil tested? We intend to make organic gardens so any specific product recommendations are also appreciated. Although the ph doesn’t show as needing adjustment should we attempt to adjust it slightly as we make the mix knowing we will be growing asparagus, Brussels sprouts, carrots, lettuce, tomatoes, herbs, etc?
Thank you for your help and advice!
Bill C
Hi Bill. I have entered your soil test values into MSU fertilizer calculator spread sheet and assumed tomatoes was one of the crops you would grow (https://soilweb.spnl.msu.edu/fmi/webd?homeurl=https://www.canr.msu.edu/fertrec/#WebClient). Based on attached info at bottom these are their recommendations. So what you add to the soil and amount depends on each product's tested analysis which you should see on the bag. I know Morgan Dairy doo based in Sears Michigan sells worm castings as well as compost and they provide the test results right on their bag. Most composts are low in NPK but that means it won't burn your plants and adds much more than NPK, but also adds organic matter which is good for the short and long term for crop health. I think if you get a well aged (one that has been turned when heated 3 x or more and more than 6 months old (reduces weed seeds). Most composts are about 3-2-2 (NPK%) so add 1/2 inch of the compost to the surface of filled beds then turn in about to 8 inches. I would try to get a non poultry compost as poultry manure is highest in phosphorous and you don't want too much in the soil for the sake of your plants and the environment as it is a nutrient that easily runs off of the soil or is leached. Since you pH is just right now you could sprinkle some lime on the surface in the spring a couple weeks pre planting to keep the pH at near neutral. I suggest if you are able is to make your beds this year then plant buckwheat in the heat of the summer then just as it starts to bloom weed whip it down, leaving roots in the soil to add to the organic matter. then after they are done plant oats which will grow into the fall. if the oats start to put out a head before frost and you don't want volunteer oats weed whip them too. Leave all of these cover crops on the top of the soil, their roots work to feed the microbes and compete against weeds and the above ground lays and protects the soil surface from erosion and compaction (yes rain falling does cause compaction amazingly). If youre garden is in an area where there are cats you may want to cover the beds with a breathable cover like weed barrier overwinter to keep it from turning into a litter box. During the growing season water your plants with water that you have added fish emulsion, another organic source of NPK (N =~ 5%) but don't water leaves but just the soil around the plants. Note the nice smell :) so don't get it on greens that will be harvested in a week or 2 unless you want pre marinated stir fry (JUST KIDDING). its not harmful to the plants or to us if we consume it. The dosage is typically 2 tablespoons to the gallon when providing nutrients. So about every other week i would add to water.
hope this helps
Vicki<personal data hidden>)
hope this helps
Vicki<personal data hidden>)