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2001 Paul Barlow

Soil Analysis

There are several ways to have your soil analysed. Cheap (and not so cheap) DIY kits can be obtained from local garden centres and DIY stores, alternatively it is possible to send soil samples away to specialist Soil Analysis firms. Over the last three years I have chosen the last option and have been particularly pleased with the results. (Link to Results Page).

To follow the growing methods I described in the Feeding Chrysanthemums page it is essential that the starting point for Nitrogen and Potash can be established and adjusted if necessary to the levels recommended.

Of course there are other important nutritional elements that should not be ignored. The soil analysis results will give guidance on these. I've made two charts that demonstrate the amounts of major and minor nutrients found when the dried leaves of chrysanthemum plants were analysed. Link to Nutrient  Charts Page.

The following diagram shows the effect of pH on nutrient availability. This chart is valid only for soil based mediums. The second chart,   further down this page shows a very different picture for soilless mediums.


It's clear from the target zone highlighted on the diagram, that between 6.5 and 7.0 all nutritional elements are available to our plants. From experience in my garden, I have noticed that there is a slight reduction in pH over the growing season. For this reason I would like to see my pH closer to 7.0 at planting out time, hoping that I still have something close to 6.5 when blooms are developing.

The line showing 5.6 is where my pH reading was when I received my first soil analysis results. At this pH level  all the major nutrients were not available to my plants - even if they were present in abundance in the growing medium. Things could only get better!

I've plotted my soil analysis results for the last three years into four graphs, you can link to these graphs from here: Analysis Graphs.  The fact that apart from pH all other results show little consistency is of little concern. What is important is knowing what the results are so that appropriate adjustments can be made.

pH chart for soilless mediums
ph2.gif soillesss

This is not the easiest chart to read, and I had some difficulty coming up with a meaningful reporoduction! Basically, the thickness of the black band is an indication of nutrient availability  along the pH scale.

Clearly the picture is a little more complicated with soilless mixes. Typically, nutrient availability is better at the lower end of the pH scale than in a soil based mix. A pH in the range 5.0 to 5.5 is generally recommended for growing in a soilless medium.

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Last updated on 16 December, 2001