Name______
Passage 1
From an agricultural standpoint pH is important because it strongly affects plant growth, nutrient availability, elemental toxicity and microbial activity. Plant Vitality is defined as the percent of the planted plants that survive based on conditions. In an agricultural sense, soil pH indirectly affects plant growth. This is because various mineral nutrients are available in varying concentrations depending on the pH of soil. At certain pH levels, certain mineral nutrients remain bound with other minerals and are unavailable to the plant.
For example, with respect to cotton, soil pH should be in the range of 5.5 – 7.0. If the pH is greater than 7, the availability of some critical nutrients, such as zinc, may become limiting. Conversely, if pH is less than 5, the availability of some needed nutrients, such as phosphorus, calcium, magnesium and molybdenum, are so low that plant uptake becomes limited.
In addition to this, some generally insoluble nutrients, such as iron and aluminum, may be released into the soil at lower pH values. The result will be reduced plant growth owing to the sensitivity of many plant roots to aluminum toxicity.
It is therefore argued that pH is the single most important diagnostic chemical measurement of soil.
Figure 1
Table 1
Soil pH / Manganese Concentration (mg/cm3) / Plant Vitality (%)4 / 30 / 65%
5 / 21 / 70%
6 / 15 / 75%
7 / 12 / 80%
8 / 10 / 85%
9 / 9 / 90%
10 / 9 / 95%
1. If this study had included a trial involving a Manganese concentration at a soil pH of 3, then the plant vitality at that pH would most likely have been:
a) 42%
b) 60%
c) 65%
d) 100%
Purpose: What is this question asking?
Look: Where are you going to find this answer?
Answer: Why is the answer you chose correct?
2. Given the information in Table 1, what would the resulting Manganese concentration be if it were measured at a soil pH of 3?
a) 26 mg/cm3
b) 36 mg/cm3
c) 42 mg/cm3
d) 50 mg/cm3
Purpose: What is this question asking?
Look: Where are you going to find this answer?
Answer: Why is the answer you chose correct?
3. Assume the trends shown in this study continue. If another sample of Manganese had been taken at a soil pH of 11, then the change in its concentration would most likely have:
a) Decreased
b) Increased
c) Stayed the Same
d) Decreased, then increased
4. Assume the trends shown in this study continue. If another sample of Manganese had been taken at a soil pH of 2, then the change in its concentration would most likely have:
a) Decreased
b) Increased
c) Stayed the Same
d) Decreased, then increased
5. A soil pH of 14 is tested. Why does a plant vitality percent of 110% not make sense?
Define Your Pride.