H1 (85) Principles of soil science AGRI20038 Clear and Concise notes

Description

These notes include hand-drawn images and information about the following content; Overview and Soils for Agriculture - Definition of soil - Soil functions - Inherent soil properties - Dynamic soil properties - Soil health - Importance of soil health - Soil health vs quality - Key soil attributes - Soil profile - Eluvial and Illuvial horizon - Solum horizon - Profile forms - Texture contrast - Key components of soil - Soil organic matter - Soil Texture – importance - Describing soil texture - Soil Colour and Characteristic - Soil pH Soil Distribution - Distribution of soils based on latitude - Köppen Climate classification - What factors influence the distribution of soils globally? - What factors cause variation in soils locally? - The world’s biomes - Formation of soil structure - Köppen A Soils - Köppen B soils - Köppen C soils - Köppen D soils - Common problem with soils from dry zone - Agriculture on soils from the dry zone: Australia - Soil topography and region - Shrink-swell soil - What can be done to soils to improve their suitability for - agriculture? - How is soil structure and bulk density related to soil properties? Soil Genesis, Morphology and Classification - Factors which influence soil genesis/soil formation - Important periods for soil formation – Northern hemisphere - Important periods for soil formation – Southern hemisphere - Transported parent material - Soil forming factor – climate and temperature - Soil forming factor – Climate, moisture - Soil forming factor – Topography - Soil forming factor – Organic activity - Soil forming factor – time - eneral model for soil formation - Additions - Losses - Transformations - Translocations - Cheluviation - Leaching - Solonisation - Podsolization - Lessivage - Master horizons - Landform morphology - Australian Soil classification (ASC) - Australian Soil classification (ASC) – main - Australian Soil classification (ASC) – - Australian Soil classification (ASC) – No texture contrast - Vertosol Chemical Processes - Primary Minerals - Secondary minerals - Surface areas - Important chemical properties of the clay fraction of soil - Colloidal component of soil - The clay faction - Secondary Silicates - Clay surface and cations - Clay composition - Montmorillonite - Illite - Kaolinite - Preference for cations on exchange surface - Isomorphic substitution - Adsorption - Specifically-adsorbed ions vs non-specifically adsorbed electrolyte - ions - Cation exchange capacity (CEC) - Anion exchange capacity (AEC) - Lewis acid/base and metal complexes - Permanent (negative) charge surfaces - Reaction of cations with permanent charge surfaces - Cation exchange on minerals with low permanent charge - Adsorption to minerals of high permanent charge - Variable charge - Development of surface charge – Variable charge surfaces - Adsorption of cations to variable charge surfaces - Adsorption of anions to variable charge surface - Variable charge and organic matter - Adsorption to charged surface - Adsorption of cations to organic matter - Reactions of cations with organic matter - Adsorption of anions to organic matter - Anions in soil solution – phosphate - Anions in soil solution – Sulphate - Anions in soil solution – nitrate – NO3- - Anions in soil solution – Arsenate and dichromate - Cations in soil solution – K - K in soil solution – Illite – Vermiculite - Heavy metal anion adsorption - Cations in soil solution – Fe and Mn - Soil Physics - Examples of hydrological challenges - Stores and fluxes of water - Water balance – local example - Water balance equation - Important properties of precipitation - Units of precipitation - Rainfall measurement methods - Evaporation - Transpiration - Evapotranspiration - Why do we want to quantify evapotranspiration? - Potential evaporation - Pan evaporation - Measuring evapotranspiration - Estimation of evapotranspiration - Evapotranspiration and vegetation - Surface runoff - Surface runoff measurements - Estimating surface runoff by infiltration measurements - Place without soil - Imagining soil - Soil pores – capillaries - Potential energy - Soil water (potential) energy - Soil water energy – definition - Saturation - Field Capacity - Permanent wilting point - Soil water potential equation - Matric potential - Classification of soil water - Plant available water - Soil-Plant-Atmosphere Continuum (SPAC) - Darcy’s law - Hydraulic conductivity and water potential - Relationship between suction and hydraulic conductivity - Measuring saturated hydraulic conductivity in the field - Infiltration - Infiltration rate: Dry vs Wet soil - Green and Ampt infiltration equation - Macropore flow; Poiseuille’s equation - Infiltration excess runoff - Saturation excess runoff - Water repellence - Compaction Land degradation - What is land degradation? - Global status of soil degradation - Effects of soil erosion - Erosion: processes - Formation of aggregates: - Colloid structure - Pore size and its function - Importance of soil structure - Flocculation - Deflocculation - Deflocculation processes - Causes of soil structural decline - Consequences of soil structural decline - Universal soil loss equation - USLE - What soil properties affect erosion? - Sodic soils; Sodosol - Sodium Adsorption ratio (SAR) - Sodosol - Problems with sodic soils - Managing sodic soils to prevent erosion - Factors that contribute to erosion - Erosion and soil structural decline: management - Types of erosion - 3 forms of wind erosion - Wind erosion - Sheetwash and Rill Erosion - Gully Erosion - Tunnel erosion - Initiation of tunnel erosion - Streambank erosion, contributing factors - Mass movement/landslides: management - Overall erosion management considerations - Salinity definitions - Primary and secondary salinity - Process of salinization resulting from clearing of native trees from a - catchment - Effects of salinity on soil - Effects of salinity on plants - Recharge and discharge control Soil Nitrogen - Why do we need to know about Nitrogen and soils? - Forms of nitrogen - Nitrogen cycle: inputs - N2 fixation - Biological nitrogen fixation - Industrial nitrogen fixation - Inputs: Fertiliser – Urea - Hydrolysis - NH3 loss from urea fertiliser - Nitrogen cycle: fate of ammonia/ammonium - Nitrogen cycle - Nitrification and pH - Organic N – soil organic matter - Mineralisation-immobilisation C:N ratios - Plant uptake of urea - Nitrate - Denitrification - N2O:N2 ratio Soil Phosphorus - Phosphorus vs. phosphorous - The phosphorus cycle in soil - P cycling in natural ecosystems - Phosphorus and productivity - Phosphorus scarcity - Phosphorus species in plants - Movement of phosphorus to plant root - How to enhance phosphorus uptake - Water soluble fertilisers - Phosphate rock fertilisers - Organic Phosphorus sources - Phosphorus fractions or pools in soil - Main transformations of phosphorus in soil - Placement of phosphorus fertilisers - Forms of organic phosphorus in soils - Other factors that decrease the effectiveness of phosphorus - How does phosphorus move? - Eutrophication Forest soils - Where does carbon in the soil come from? - History of the Earth - The carbon cycle - Forests and their role in carbon cycling - The soil carbon store - Soil profile and organic matter - Agriculture and organic matter - Organic matter – rates of decomposition - Definition of soil organic matter - Measurement of soil organic matter - Soil organic matter and atmospheric carbon - Aspects of the carbon cycle - Types of soil organic matter - Composition of soil organic matter - Extraction of soil organic matter - Characteristics of the Humic fraction – HA, FA, Humin - Typical elements analysis of humus - Functions of soil organic matter - Soil organic matter cation exchange - Soil biota - Micro-organisms in soil - Bacteria - Actinomycetes - Fungi - Energy and carbon sources for classes of soil organisms - Energy and principle carbon sources of the microorganisms - Physiological groups of soil organisms - Soil microbial biomass - Soil Fauna - Soil mesofauna - Summary of influences of soil biota on soil processes - Catabolism - Formation of soil organic matter - Decomposition and Humus formation - Decomposition of plant residues - Rate of decomposition - Environmental factors affecting decomposition of organic matter - Effect of soil type on decomposition of organic matter - Effects of management on SOM - Conserving SOM in farming - Mineralisation of carbon in soils - SOM turnover - Decomposition facts - Nutrient cycling Soil biological processes and amendments - Soil degradation timeline - Types of organic amendments - Framework of how organic amendments work - Effects of organic amendments - Issues with soil amendments - Soil amendments and agricultural industries - Subsoil manuring - Combined amendments with lime - On-farm (brown manures) and calcium nitrate - Conclusions