soil amendments - Ask Extension
I recently rebuilt my garden to raised beds and large containers. First, I would like to know where i can get the soil tested and analyzed. I tried to...
Knowledgebase
soil amendments #817070
Asked November 30, 2022, 10:45 AM EST
I recently rebuilt my garden to raised beds and large containers. First, I would like to know where i can get the soil tested and analyzed. I tried to grow lima beans in one bed and string bean in the other. The string beans took 6 month to mature and the limas were all bush and almost no beans. I started testing the soil ph too late. The ph in all the beds and pots was 8! No wonder I had problems. I need to know how to get the ph down to the 6 to 7 range and keep it there. And I need to know what nutrient are missing that the beans need to really produce. The soils I'm using come from a number of different sources but they all seem to be equally deficient.
Frederick County Maryland
Expert Response
Home soil pH testers are notoriously inaccurate. A soil pH reading of 8.0 is unusual and suspect.
It is quite possible that your soil does need amending, but not necessarily due to the pH value.
Can you tell us more about where/what soil types and sources you are using? That would help us to determine if you need a soil test. It could be due to other factors and we are happy to guide you with all of it.
For instance, 'top soil' is mostly mineral and
putting mineral soil in containers will lead to poor growth from compaction, and reduced aeration.
This page is about organic matter and soil amendments: https://extension.umd.edu/resource/organic-matter-and-soil-amendments
In the case of your lima beans, very strong lima bean plant growth and no flowers or beans suggest too much Nitrogen from fertilizer. With excess N, plants are encouraged to produce a beautiful flush of foliage at the expense of flowers and fruits.
We have great pages on individual vegetables that you may like, and here is our Vegetable growing info:
https://extension.umd.edu/resource/vegetables-home-garden
Here is our soil testing information:
https://extension.umd.edu/resource/soil-testing-and-soil-testing-labs
Christine
It is quite possible that your soil does need amending, but not necessarily due to the pH value.
Can you tell us more about where/what soil types and sources you are using? That would help us to determine if you need a soil test. It could be due to other factors and we are happy to guide you with all of it.
For instance, 'top soil' is mostly mineral and
putting mineral soil in containers will lead to poor growth from compaction, and reduced aeration.
This page is about organic matter and soil amendments: https://extension.umd.edu/resource/organic-matter-and-soil-amendments
In the case of your lima beans, very strong lima bean plant growth and no flowers or beans suggest too much Nitrogen from fertilizer. With excess N, plants are encouraged to produce a beautiful flush of foliage at the expense of flowers and fruits.
We have great pages on individual vegetables that you may like, and here is our Vegetable growing info:
https://extension.umd.edu/resource/vegetables-home-garden
Here is our soil testing information:
https://extension.umd.edu/resource/soil-testing-and-soil-testing-labs
Christine
Thanks for your response Christine,
In the raised beds which are 4' x 8' x 2'h. I layered my material. At the bottom is a layer of old wood that beginning to rot then a layer dead grass. That was the bottom half but it compressed. On top of that I have " garden compost" from the Frederick Co. Landfill that they certify as being tested for herbicides and pesticides and other noxious stuff. It is ground very fine and it mixes well with other soil. The top layer is soil I purchased from a company in Baltimore. It's certified organic pesticide and herbicide free and I mixed a little of the compost into it. It stayed loose and never got compacted all year.
All my plants were started in flats and then transplanted into the beds around the end of May. Most of my pots are 15 gal. and are a mix of the garden compost above, bagged garden soils from Lowe's and Home Depot which I've been using for a few years and composted cow manure. I don't use any bagged top soils because they turn into brick material.
Every year I dump my pots out, de-weed them, mix in something like Job's organic fertilizer for vegetables then back in the pots. I planted zucchini and yellow squash, one in each pot and they went berserk. So they liked the soil I had. I fertilize during the season with a fertilizer that's low in nitrogen and higher in Phosphorus. It used to be called 5-10-5 but I haven't seen those numbers in a long time. I put triple phosphate on my potatoes but all I got were marble size. I thought the soil might be missing some trace minerals the plants need so that's why I want to get it analyzed. I have some test strips that I use for our Koi pond so I'll try to use those to test my Ph meter for accuracy.
Thanks,
Bryan
Hi-
We assume the 4X8 garden beds are sitting on top of the soil and are not on a hard surface like concrete or blacktop.
In the future, we would suggest when making beds to use follow the recommendations on this web page:
https://extension.umd.edu/resource/soil-fill-raised-beds
If the Baltimore soil you bought was >50% compost the soil in your beds may be too high in organic matter for a soil lab to test it as soil, which is mostly made up of minerals- sand, silt, and clay. Some soil testing labs (Penn State, University of Delaware) do test compost and soilless growing media.
For the containers, the growing mix is high in organic matter which continues to degrade into smaller and smaller particles that can reduce aeration if the same material is used year after year. If the container plants grew well this may not be a problem yet for you.
Plants need about 4X as much nitrogen as phosphorus (P) so fertilizers high in P are not helpful unless your soil is deficient in P.
Here's our web page on fertilizing vegetables:
https://extension.umd.edu/resource/fertilizing-vegetables
Jon
We assume the 4X8 garden beds are sitting on top of the soil and are not on a hard surface like concrete or blacktop.
In the future, we would suggest when making beds to use follow the recommendations on this web page:
https://extension.umd.edu/resource/soil-fill-raised-beds
If the Baltimore soil you bought was >50% compost the soil in your beds may be too high in organic matter for a soil lab to test it as soil, which is mostly made up of minerals- sand, silt, and clay. Some soil testing labs (Penn State, University of Delaware) do test compost and soilless growing media.
For the containers, the growing mix is high in organic matter which continues to degrade into smaller and smaller particles that can reduce aeration if the same material is used year after year. If the container plants grew well this may not be a problem yet for you.
Plants need about 4X as much nitrogen as phosphorus (P) so fertilizers high in P are not helpful unless your soil is deficient in P.
Here's our web page on fertilizing vegetables:
https://extension.umd.edu/resource/fertilizing-vegetables
Jon
