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soil test kit accuracy?

I picked up a soil test kit at TSC for 3.99. Has these little tubes and capsules in it.

how accurate are these? is it worth relying on?

Last year I noticed my garden didn't seem to grow anything very well. So I figured I'd give this a shot. I did the ph test and the nitrogen test so far.

PH shows akaline. it's pretty green in there. the chart only shows four results, 8.0=akaline, 7.0=medium, 6.0=acid, 5.0 = very acid. mine seems to be somwehere between 7 and 8.

the nitrogen is pink, def not high zone pink but can't really tell between the other three choices.

how bad is it to have an alkaline soil? Will adding sheep manure that's been aged still allow good growth or is it an issue that needs to be addressed quickly?


  • nutcutletnutcutlet Posts: 27,166

    An alkaline soil isn't bad john. Alkaline describes the soil, it's not a criticism. Many plants prefer it.

    I've always had alkaline soil in my gardens.

    In the sticks near Peterborough
  • ObelixxObelixx Posts: 29,160

    Did you use demineralised water?   Tap water may make the results more alkaline.

    Having said that, alkaline is great as long as you don't try to grow ericaceous plants like camellias, azaleas, rhodos and some others.   My garden is fertile alkaline loam on a clay subsoil - great for clematis, honeysuckles, roses, all sorts of shrubs, tres, perennials and bulbs and also good for veggies.   Brassicas like alkaline soil as it helps fight club root.

    Adding fertiliser is always going to help but it's best applied as a mulch of garden or municipal compost in autumn to condition the soil and then well rotted cow, horse or sheep manure in late winter so the goodness doesn't get leached out by all the winter rains.   You can also scatter pelleted chicken manure or blood, fish and bone if foxes aren't a problem.   You can make a liquid feed from nettles to give a nitrogen boost to leafy plants and a comfrey feed for plants which will flower or produce fruits.

    Vendée - 20kms from Atlantic coast.
    "We don't stop playing because we grow old; we grow old because we stop playing." - George Bernard Shaw
  • johngreenjohngreen Posts: 58

    Okay that's good news. I used natural spring water from the stuff i was drinking at the time to do the tests.

    my nitrogen, phosphorous and pot were all in the very low margins! no wonder nothing grew well last year! growth was crazy slow last year it was nuts. So i guess I've definitely got a problem here with ferts

  • No expertNo expert Posts: 415

    Collect some rain water on a plastic sheet. This will give you almost pure water for the test. We add lime to acid soils, so lime water will give a more alkaline result. Have a very black loamy soil here and it is on the Alkaline side as can be seen by the scab on the spuds in my profile pic.

  • They are a good indicator when used correctly, the chemistry is standard. Try testing in summer as well, the nutrient status usually perks up as the micro and mesofauna become more active and surprise plants lift nutrients. Rainwater is acidic BTW.

    You could test the pH of the water you use and if you don't want to use all your litmus strips you could use turmeric, red cabbage, radish or one of many other garden veg with pH-sensitive anthocyanins as pH indicators. 

    Beside the pH and mineral content the texture, structure, porosity,  water potential, micro and mesobiology of your soil are important. 

    There are so many things one would look at before the pH and soil nutrient levels. Location? Is your soil sandy? Is your soil bare over the winter? With some moisture in it does it hold in a ball. Does it form large clumps which fall apart when you squeeze them? Are there very small, hard aggregates of soil?

    It's the UN International Year of Soils, so there should be a lot of events and public  access material about on soil science just now. I had a look for YouTube content from the Mccaulay (James Hutton Institute), which is local.. but nothing. Nothing much in the way of actual soil science on YT from UC Davis. Cornell has a few videos. Berkeley has whole video courses on most STEM topics but it won't have anything with Davis being the Agri campus. I've just got rid of the remnants of Apple and its bloatware from my PC but you could also look up iTunesU for soil science courses. 

    There's an accessible-looking series of videos on soil science on Youtube from Walla Walla Community College WWCCSoils (Walla Walla is the town in Washington State known for its large sweet onions) It might be accessible to non-scientists / non-STEM people. It looks the most comprehensive from a short YT search, though you could look up the 'extensions' of the major North American unis (soils may be bundled in with IPM).

    If your soil has leached nutrients to the underworld or if your structure is poor and lacking humic material you could put down a rapidly establishing lifter and integrate it in as soon as 4 weeks time (assuming the soil is warm enough). You might need to wait a further few weeks to sow anything else but plug plants tend to be less critical of  recently integrated green manure than direct sown. I'd recommend a winter green manure (eg rye and vetch) this coming winter which is good in alkaline soil. A local agri seed merchant would easily sort you out with a green manure suitable for your situation.

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