All about potatoes.pdf - Vegetableipmasia.org

3.
SOIL
• Observe the sediment: the top layer of sediment will be loam, under that will be
clay, with sand at the bottom.
• Compare these three components, and determine each soil type based on the soil
textural triangle (See figure 2).
Figure 2: Soil textural triangle
3.1.2 Soil acidity
The pH of soil indicates the level of acidity and is measured by using a pH meter.
Unfortunately this is quite expensive, so a cheap and easy method for measuring pH
balance is to use litmus paper, which you can buy at any pharmacy. Instructions on
how to use it will be found on litmus paper packaging. The lower the pH level, the
higher the acidity, while the higher the pH level, the lower the acidity. Potato plants
grow well in soil with a pH value of between 5.0 and 6.5. Potatoes planted in soil with
pH levels lower than this will produce poor quality tubers and abnormal growth.
Potatoes planted in high pH soil will have problems with common scab.
Generally, soils in potato producing areas have high acidity or pH levels below 5.0.
The lower pH soil is caused, among other things, by the use of acidic chemical
fertilizers, particularly urea and ammonium sulfate. Adding lime and/or reducing use
of urea and ammonium sulfate fertilizers can increase the pH level of a soil. One kind
of liming material is dolomitic limestone, which is added to soil four weeks before
planting. Quantities have to be adjusted in accordance with requirements and soil
type. The amount of lime required is measured based on the initial soil pH and the
desired pH increase. Estimated amounts of lime required for increasing pH of
different soil types are displayed in Table 1 below. It may take several seasons
before the soil pH is close to neutral. Liming of soils with a pH higher than 6 is not
recommended, since further increase in pH may induce potato common scab.
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ALL ABOUT POTATOES