Page 30 - Ilmu Tanah

The Chemistry and Fertility of Soils under Tropical Weeds 17

1.3 Scope of The Chemistry and Fertility of Soils under

Tropical Weeds

This book is organized into nine chapters. Chapters 1 (Introduction) briefly
focuses on the interrelationship between the chemistry of soils and the existence
of plants and weeds in the soil environment. Chapters 2 (The Soil – Weed
Interrelationships) describes more specifically the interrelationship between the
chemistry of soils and the growth of weeds while Chapter 3 (The Important Facts
about Tropical Weeds) briefly describes the important weeds of the tropics: their
concepts, their effects, invasion and dominance, and their control and
management. Chapters 4 - 9 deal with the effects of weed presence on the
chemistry of soils that include soil pH and soil enzymatic activities (Chapter 4:
Effects of Forest Conversion, Chapter 5: Effects of Tropical Weeds on Soil pH and
Enzymatic Activities), soil contents of carbon, nitrogen, phosphorus, and sulfur
(Chapter 6: Effects of Tropical Weeds on Soil Carbon, Nitrogen, Phosphorus, and
Sulfur), soil exchangeable potassium (Chapter 7: Effects of Tropical Weeds on Soil
Potassium), and heavy metals (Chapter 8: Effects of Tropical Weeds on Heavy
Metals). Chapter 9 (Closing Remarks) highlights some important conclusions
related to the effect of weed existence on the chemistry and fertility of soils.
This discussion is completed with tables and diagram of researches reported in
several scientific journal conducted by the authors by employing tropical soils of
Lampung Indonesia. Some data from other parts of the world were also used in the
discussion.

Key Questions

1. How do weeds affect the soil chemical properties? What soil chemical properties are
affected the most?
2. Explain how weeds change the soil reaction (pH) and indirectly affect the soil negative
charges and cation exchange capacity!
3. What are the difference between soil pH and soil E?
4. Explain the chemical properties of soils? Why are the soil pH and soil E considered the
master variables!
5. How do the soil pH and the soil E control the dominance of Fe species in the soil – water
system?

Abdul Kadir Salam and Nanik Sriyani – 2019