Page 148 - Ilmu Tanah

The Chemistry and Fertility of Soils under Tropical Weeds 135

Key Questions

1. How can weed roots increase the soil soluble and exchangeable K? Explain the sources
of K and how these sources release K!
2. How do the soil minerals weather? Explain an example that includes the effect of soil
pH on accelerating the process!
3. Explain the release of K from organic K sources! How do soil enzymes participate in this
process?
4. What is the effect of Root-To-Shoot ratio on nutrient release from soil minerals? How
does the mass distribution between root and shoot in marginal soils? What happen in
fertile soils?
5. Explain all K forms in the soil system and their relationships with the plant root
absorption!
6. Explain the supplies of K from soils! How do the supplies relate to each chemical form
of K in the soil system?
7. Explain the nutrient element sources in the soil system and the mechanisms of releases
of their nutrient elements!
8. What are the important factors that control the release of nutrient elements in soils?
Explain!
9. Explain the relationship between the release of K from soil minerals versus soil pH,
water, and leaching! Describe it with graphs!
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10. Explain the effects of soil water and H in the weathering of orthoclase! What
conclusion you can make from this reaction?
11. Explain the availability of soil K!
12. Explain the relatonship between the availability of K and their chemical forms in the soil
system!
13. How is the release of K from organic sources in the soil system? Explain!
14. What are the important factors controlling the release of K from organic matters? How
does each of these factors accelerate the process?
15. Explain the fates of the released K from organic matter decomposition in the soil-water
system!
16. Explain the effect of soil pH on the rates of soil mineral weathering! How does each
factor accelerate the process?
17. Explain how to increase the weathering of orthoclase in the soil system!
18. Explain the effects of organic acids on the soil K?
19. Explain the effect of K releasing bacteria! How can you manage the bacteria to enhance
the soil mineral weathering!
20. How does A pintoi stimulate more K release in the soil system? Explain it with some soil
chemical reaction!
21. Explain the role of RSR in K release in the soil system!

Abdul Kadir Salam and Nanik Sriyani – 2019