Name_______________________

Quiz 3 May 24, 1999

Choose the one best response.

1. Sulfur is taken up by plants from the soil in which form?

a. SO4

b. SO₂

c. H₂S

d. S⁰

Match the nutrient with its corresponding situation where it is likely to be deficient (you can use a letter more than once but there is only one best answer).

2.	Cu___	a. Coarse textured soil low in organic matter
3.	B ___	b. High organic matter soil
4.	S ___	c. Acidic soil
5.	Mo___	d. Soils with 2:1 clays

6. If a soil is flooded or kept very wet for long periods Mn would likely under go which of these reactions?

a. reduction of Mn2+ to Mn3+

b. oxidation of Mn2+ to Mn3+

c. reduction of Mn3+ to Mn2+

d. oxidation of Mn3+ to Mn2+

7. Which factor does not increase S mineralization?

a. decreasing soil temperature

b. wetting/drying cycles

c. C:S ratio of 100:1 of organic residue added to soil

d. presence of plants

8. Which form of S in aerobic soils is thought to be the source from which most S is mineralized due to biological activity?

a. FeS

b. Calcium carbonate-sulfates

c. H₂S

d. ester sulfate

9. Which statement about elemental S is true?

a. provides S that is directly available to soils

b. causes alkalinity in soils

c. must be oxidized to SO₄ before it is available for plant uptake

d. causes acidity in soils

e. c and d

f. b and c

g. a and b

5) 10. You are working as a field person and have long-term sweet corn yield data for field. The results show yields and crop quality have been maintained at slightly higher levels than the average of the farmers at the cannery where the grower sells her crop, including the last time the grower grew corn 3 years ago. A B soil test indicates you were deficient in B quite good, what information about the field should you obtain and what questions might you ask of the lab before making a decision about B fertilization?

4) 11. What are the advantages of using elemental S over ammonium sulfate where a S deficiency has been identified in a pasture that has a mix of legumes and grasses?

4) 12. What is a chelate and why is it used in fertilization with some nutrients? Name two nutrients that can be applied in the chelated form.

4) 13. Why do most micronutrients (except Mo) become less available to plants when soil pH is greater than 7.0? Indicate a generalized reaction that might account for this.

Extra credit

5) 14. (a) Provide 3 factors in soils that contribute to Ca being deficient in soils (Do not list more than 3 factors as I will only grade the first 3 factors you list). (b) What is grass tetany and how can this problem be corrected?