Page 124 - Ilmu Tanah

The Chemistry and Fertility of Soils under Tropical Weeds 111

22. What is oxidation, reduction, and redox reactions of hydrocarbons? How do these
reactions relate to the soil environment?
23. What are the electron acceptors and electron donors in soil system? Give some
examples and their roles in the soil environment!
24. What are the alternative electron donors in the soil system? Are these compounds are
limited in the soil environment?
25. What are the effects of deforestation on soil total N and organic C or soil organic
matter?
26. What are the effects of deforestation on soil P? Explain why!
27. How do weeds and natural vegetation in coffee plantation maintain the soil organic C
and total N?
28. How does the tillage system affect soil organic C and organic matter content? Explain
with examples!
29. Why are the activities of soil enzymes higher in no tillage than those in tillage soils?
How does this phenomenon relate to soil physical and chemical properties of soils!
30. How does the the effects of continuous cropping on soil C, total N, and available P?
Explain!
31. What are the differences of the effect on soil organic C of grasses versus food plants?
32. What are the effects of deforestation on the activities of soil enzymes? Give examples!
33. Explain the relationship between the soil depth vs the soil enzymatic activities! Explain
why!
34. Explain the relationships between the soil enzymatic activities vs the soil organic C and
total N content? Describe it with graph!
35. What are the effects of plant covers on soil enzymes? Explain why!

Abdul Kadir Salam and Nanik Sriyani – 2019