Soil pH
Thanks to CynicalDrivel for mentioning the need to pH test soil here
I’ve looked into this a little, having previously had very little knowledge of the difference in the outcome of crops depending on soil acidity.
The pH of soil tends to run from 4 (considered highly acidic) to 8 (alkaline) with 7 being neutral. Most nutrients become available in soil with a pH between 6 and 7 but specifically:
Nitrogen (N) is available at pH 5.5 or greater, Phosphorus (P) is available at pH 6-7 and Potassium (K) is available as quoted:
Soil type and environmental conditions have an effect on the amount of potassium available for plant use. Potassium availability is highest under warm, moist conditions in soils that are well aerated with a neutral or slightly acidic pH. Too much water in the soil profile will lower oxygen levels, which in turn decreases plant respiration reducing potassium uptake. In clay soils, potassium availability can be affected due to its competition with calcium and magnesium for sites on the cation exchange. Both calcium and magnesium can easily displace potassium from the cation exchange
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You can get an idea as to whether the soil is more acidic or alkaline depending on plants that are already growing in the area. If there are Hydrangeas close by or on your plot, they will flower blue with acidic soil and pink with alkaline.
A really quick, cheap and easy way of finding out if your soil is acidic or alkaline is here. It won’t tell you the exact pH, but will tell you which ball park you’re in. Another good indicator, like with the hydrangeas, is the type of weeds on your plot
Weeds as Indicators
Does your lawn or garden seem to favor particular types of weeds? Certain weeds can act as indicators of your soil's pH. For example, sorrels, docks, dandelions, and Queen-Anne's lace typically grow in poor, acidic soils. On the alkaline side of the pH scale, mustards and thistles tend to grow in soils with a higher pH. Changing the pH can actually help reduce the incidence of certain types of weeds.
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If you want a more accurate reading of the soil pH the best bet is to invest in pH testing kit or meter, which can easily be found with google et al.
I searched for a soil testing kit on amazon and found them with process ranging from £1.05 for a test-tube type kit with “2 powder capsule tests for soil pH levels” to £37.95 for a wand type meter with "soil analysis pH, N P and K with enough materials for 40 tests "
Soil acidity/alkalinity as per the pH are as follows:
Ultra acid <3.5
Extreme acid 3.5 - 4.4
Very strong acid 4.5 - 5.0
Strong acid 5.1 - 5.5
Moderate acid 5.6 -6.0
Slight acid 6.1 -6.5
Neutral 6.6 - 7.3
Slightly alkaline 7.4 - 7.8
Moderately alkaline 7.9 - 8.4
Strongly alkaline 8.5 -9.0
Very strongly alkaline >9.0
Soil Types
In terms of soil texture, soil type usually refers to the different sizes of mineral particles in a particular sample. Soil is made up in part of finely ground rock particles, grouped according to size as sand, silt and clay. Each size plays a significantly different role.
For example, the largest particles, sand, determine aeration and drainage characteristics, while the tiniest, sub-microscopic clay particles, are chemically active, binding with water and plant nutrients. The ratio of these sizes determines soil type: clay, loam, clay-loam, silt-loam, and so on.
In addition to the mineral composition of soil, humus (organic material) also plays a crucial role in soil characteristics and fertility for plant life. Soil may be mixed with larger aggregate, such as pebbles or gravel. Not all types of soil are permeable, such as pure clay.
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The best soil to work with is loam. If your soil is too clayey/petey, or silty/sandy adding compost is beneficial. In clayey soil it helps reduce moisture retention in wet conditions or helps disperse the moisture so it doesn’t clump. It also makes sure it doesn’t bake hard with a lack of moisture in dry conditions. Compost in silty/sandy soil will help retain moisture that would otherwise drain away. A really good and much more detailed description of the 6 soil types is here
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