Soil Chemistry: An Environmental Perspective (October 2024) - PDF

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DistinctiveOrientalism

Uploaded by DistinctiveOrientalism

USTP Cagayan de Oro

2024

OCR

Professor ALMA N. ABUG

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soil chemistry environmental science soil properties ecosystems

Summary

This document provides a lecture on soil chemistry, covering its role in environmental science, including ecosystem functioning. It details the chemical properties and functions of soil, and its relevance in sustainable land management and various topics like nutrient management, pollutants and remediation, climate change, and other essential topics.

Full Transcript

October SOIL CHEMISTRY 2024 An Environmental Perspective Exploring Soil's Chemical Properties and Functions Presented by: Professor ALMA N. ABUG USTP CDO Environmental C...

October SOIL CHEMISTRY 2024 An Environmental Perspective Exploring Soil's Chemical Properties and Functions Presented by: Professor ALMA N. ABUG USTP CDO Environmental Chemistry 2 Soil chemistry is the study of the chemical composition, properties, and reactions of soils. It involves understanding how different chemical elements and compounds interact within the soil environment, including nutrient availability, pH levels, organic matter decomposition, and the effects of contaminants. Environmental Chemistry 3 Soil chemistry examines the behavior of key soil components—such as minerals, organic matter, water, and air—and how these components affect the overall fertility and health of the soil. Environmental Chemistry 4 Relevance of Soil Chemistry to Environmental Science Students: 1. Understanding Ecosystems: Soil chemistry plays a crucial role in ecosystem functioning by influencing plant growth, water retention, and nutrient cycling. For environmental science students, it provides insight into how soils support plant and microbial life, forming the foundation of terrestrial ecosystems. Environmental Chemistry 5 Relevance: 2. Soil as a Natural Resource: Soil chemistry helps students understand soil as a finite and essential resource, which is critical for agriculture, forestry, and biodiversity. It emphasizes sustainable soil management to protect this resource from degradation due to human activities like deforestation and urbanization. Environmental Chemistry 6 Relevance: 3. Nutrient Management: Environmental science students learn about nutrient cycling, including the nitrogen, phosphorus, and potassium cycles. Understanding how nutrients are retained or leached in soils helps them evaluate agricultural practices and ecosystem restoration efforts. Environmental Chemistry 7 Relevance: 4. Pollution and Remediation: Soil chemistry is essential for understanding the behavior of pollutants in the soil. Environmental science students learn how heavy metals, pesticides, and other contaminants move through soil, affecting water and air quality. It also provides knowledge on soil remediation techniques to mitigate contamination. Environmental Chemistry 8 Relevance: 5. Climate Change and Carbon Sequestration: The study of soil chemistry allows students to explore the role of soils in sequestering carbon, thus helping to mitigate climate change. They learn how soil organic matter contributes to carbon storage and how changes in land use can influence greenhouse gas emissions. Environmental Chemistry 9 Relevance: 6. Sustainable Land Management: By studying soil chemistry, students can evaluate sustainable land-use practices, such as crop rotation, use of fertilizers, and conservation techniques. This is critical for ensuring long-term food security and maintaining healthy ecosystems. Environmental Chemistry 10 Overall, soil chemistry provides environmental science students with the scientific foundation necessary to understand soil’s role in the environment, assess human impact, and develop solutions for sustainable land and resource management. Environmental Chemistry 11 Components of Soil. Presence of MINERALS Soil TEXTURE Minerals are the solid, inorganic Soil texture refers to the components of soil and are critical for relative proportion of different- its structure and fertility. sized mineral particles in the They originate from the weathering of soil, primarily sand, silt, and rocks and form the basic framework of clay. the soil, influencing its physical and chemical properties. These particles determine how Soil minerals are categorized into two the soil feels and significantly types: affect its water-holding a. primary and capacity, permeability, and fertility. b. secondary. Environmental Chemistry 12 PRIMARY MINERALS: These are minerals that have not undergone significant chemical alteration and are directly derived from the parent rock. Examples include quartz, feldspar, and mica. These minerals are typically found in sand and silt particles. SECONDARY MINERALS: These are formed through the weathering of primary minerals and include clay minerals like kaolinite, montmorillonite, and illite. Secondary minerals are essential in holding nutrients and water in the soil, playing a vital role in soil fertility. Environmental Chemistry 13 Functions of Minerals in Soil: Nutrient Supply: Many essential plant nutrients, such as potassium, calcium, and magnesium, are derived from soil minerals. Soil Structure: Minerals contribute to the soil's physical structure by forming aggregates that affect aeration and water retention. Water Retention: Clays and other fine mineral particles hold water, making it available to plants. Environmental Chemistry 14 Type of Particles in Soil Sand: Clay: Sand particles are the largest soil particles, ranging Clay particles are the smallest, less than 0.002 mm from 0.05 mm to 2 mm in diameter. in diameter. Sand feels gritty and does not hold water well due Clay feels sticky when wet and hard when dry. to the large spaces between particles, allowing Because of the fine particles, clay soils hold water water to drain quickly. and nutrients very well but can have poor drainage and be difficult for roots to penetrate. While it provides good aeration, its low nutrient- holding capacity makes it less fertile. Loam Loam is a soil texture that has roughly equal parts Silt: sand, silt, and clay. Silt particles are medium-sized, between 0.002 mm It is considered the ideal soil texture for agriculture because it provides a balance of good drainage, and 0.05 mm in diameter. nutrient retention, and root support. Silt feels smooth or floury when dry and becomes slippery when wet. It retains water better than sand and provides moderate drainage and fertility. Environmental Chemistry 15 Why Soil Texture Matters: Water Retention and Drainage: Soils with higher sand content drain quickly, while those with more clay retain water longer. The texture affects how well soil holds or loses water. Aeration: Larger particles, like sand, allow air to circulate through the soil, supporting root respiration and microbial activity. In contrast, clay soils can become compacted, limiting aeration. Nutrient Availability: Fine-textured soils, especially those high in clay, have a greater capacity to hold onto nutrients, making them available to plants over time. In summary, minerals provide the essential nutrients and structure of the soil, while soil texture determines how water, air, and nutrients are distributed within the soil environment. Understanding both components is vital for managing soil health and optimizing plant growth. Environmental Chemistry 16 Activity 4 (Individual) 1. Why is soil pH important for Agriculture? 2. How can farmers adjust soil pH for optimal growth? 3. How do human activities (eg farming, industrial waste) influence soil pH? 4. Identify plants that grow in each type of soil and relate this to the soil’s pH. Environmental Chemistry 17 THANK YOU! Prof A Email [email protected]

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