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farrmerjon

help with soil test results

11 years ago

vegetable garden

ph 7

P lb/a 166

P ppm 83

BCSR: K 3.1 Mg 14.4 Ca 82.5

organic matter 7.9%

CEC: 17.6

The two questions/concerns I have involve nitrogen and phosphorus.

nitrogen - am I going to need any this year considering the nitrogen that should be available from the organic matter in the soil? I grow vegetables and had problems with big plants/small yield last year. I think that was from too much nitrogen last year. I was planning on only adding about half of the compost I did last year. compost is the only fertilizer I use.

phosphorus - in the literature I got with the soil test it said that phosphorus is low and 200-600 is a normal range. but from what I have read online that seems pretty high. so I am confused as to what amount of phosphorus is ideal.

any other comments about my numbers would be appreciated, thanks

Comments (5)

  • 11 years ago

    Your soil pH is very good, that should be in the 6.0 to 7.0 range.

    Phosphorus may be a bit low depending on how it is reported, pounds per acre or parts per million. Most any source of P you add now would not be available to the plants (except superphosphate) until the Soil Food Web converted it into a plant useable form. I find numbers all over the place when looking for information about P in soil with some places talking about ppm and others about lb/a, with numbers ranging from 150 ppm upward and 40 lb/a upward.

    Nitrogen availability is dependent on soil temperature which determines that activity of the Soil Food Web which feeds the plants.

    The CEC (Cation Exchange Capacity) is good. That should be in the upper teens to low twenties and is an indication of how well the soil will hold onto and release the nutrients that are there.

    Organic matter is very good. That should be in the 6 to 8 percent range.

    However, a single soil test does not tell us much unless there are others to compare with to see what is happening with the soil and if we are managing it right.

    kimmq is kimmsr

  • 11 years ago

    Thank you for taking the time to respond. Overall I'm pretty happy with the results. I seem to have enough of all the major nutrients, except possibly phosphorus. I live in zone 6 so there should be plenty of warm weather this summer to get the organic matter digested. I'm still just not sure if I should add more compost this year or not for the nitrogen. If i do it will be much less than in years past. I have been for the past 4 years including leaf mulch which the soil just gobbled up

  • 11 years ago

    Keep in mind that organic matter is the one part of the soil equation we control the most. The mineral component, the sand , silt, or clay, we have little control over unless we import a lot of something. The water component we do have a little control over as we do the air component (too much water decreases the air). But we need to replace the organic matter as it is digested by the Soil Food Web, but carefully so as not to get too much mixed in the soil.

    kimmq is kimmsr

  • 10 years ago

    Converting ppm to lbs/acre

    ppm can also be written as mg/kg. If one assumes than an acre plow layer (an acre of land 6" deep) weight 2 million pounds, one can convert ppm to lbs/acre by dividing by 2.

  • 10 years ago

    You should only need to add nitrogen if the plants seem like they need it. I have had plenty of plants grow very well that I added nothing but compost to. And others that are heavy feeders like rhubarb that seem to need additional help.