Physical Factors Soil Analyses PDF

SOIL ANALYSIS -Aspects of Environmental Monitoring... Physical Factors – Introduction  Provides organisms essential materials such as light, temperature, water, nutrients, and others  Organisms are not just passive recipients of vital resources ◦ Living organisms plays a hand in modifying t...

SOIL ANALYSIS -Aspects of Environmental Monitoring... Physical Factors – Introduction  Provides organisms essential materials such as light, temperature, water, nutrients, and others  Organisms are not just passive recipients of vital resources ◦ Living organisms plays a hand in modifying their physical environment to suit their needs  In this relationship, the environment controls the rate of change, while organisms control the direction and the quality of change – Among all organisms, man instigates the most profound effect on the environment Soil Analysis Why interested in studying the physical environment? 1. Physical environment is indispensable to all living organisms 2. Physical environment is gravely threatened by anthropogenic activities  Air, water, and land quality has undergone drastic changes during the last century because of the advances in technology and man’s careless ways Soil Analysis  Particular attention to the research methods which measures the physical and chemical factors that are operationally significant to the life cycles of organisms Soil Analysis  What’s the purpose of this study? Soil Analysis Objectives  Describe the range of physical factors commonly measured for environmental research monitoring  Establish the ecological significance of these factors and  Identify and describe the principles of the method for measuring these physical factors Soil Analysis Soil Quality  Humans are dependent on soil  Good soils are dependent upon man and the use he makes of them  no matter how advance his civilization and technology are, man is still dependent on the six-inch thick topsoil.  Plants grow naturally on soil (food, wood, medicine, animals.  Mans living standards are often determined by the quality of his soils and the kinds and quality of plants and animals grown here Soil Analysis  There are various signs that human activities threaten the quality of the soils  continuous cultivation  use of chemical fertilizers  pesticides  acid rain Causes negative impact on soils Soil Analysis Soil Quality Objectives:  Familiarize the common indicators for soil quality These indicators are sensitive to changes in soil quality Soil Analysis Common indicators for soil quality 1. Soil pH  acidity of soil is the standard parameter to detect changes in soil reaction  microorganisms and plants respond so markedly to their chemical environment  soil pH is an extremely useful indicator for the general physiological condition of the soil  3 conditions in the soil are possible 1. acidity 2. neutrality 3. alkalinity Soil Analysis  What are chemical attributes of the soil that correlates to soil pH? Very acidic/low pH  soil is dominated by exchangeable aluminum ions and H+ and Al3+ dominate  trace elements in soil are also high but the the rest of essential elements in the soil are low Higher pH values  the exchangeable bases predominate In general, a pH range of approximately 6-7 seems to be the most ideal condition for planting as it provides plants its needed nutrient (Buckman and Brady, 1969) Soil Analysis Determining Soil pH Two methods of determining soil pH 1. Electrometric Method  most accurate method of determining soil pH is by means of pH meter 2. Dye Method  a very simple and easy method but somewhat less accurate  many dye change color with an increase or decrease of pH, making it possible to estimate the approximate H+ - ion conc. of a solution  by using a number of dyes, a range of pH from 3 to 8 is easily determined  in determining such pH conc. on the soil, the sample is saturated with the dye and after standing in contact for a few mins a drop of the liquid is run out and its color observed Soil Analysis  Soil Organic Matter (SOM) What are the advantages if forest is converted into agricultural use? Will the crop yeild continuously increase? why? SOM content is widely seen as a major factor in the decrease of soil fertility after soil is converted to agricultural use  25% of SOM is rapidly lost a year after clearing of secondary forest  continuous ploughing, drainage and liming promotes mineralization and speeds up soil depletion  SOM therefore is an important indicator of soil quality Soil Analysis Soil Moisture (SM)  fundamental to plant organisms  no environmental study would be complete without measuring SM  very dynamic  when precipitaion reaches the soil, part of it runs off as surface flow, some evaporates into the atmosphere, while the remainder percolates into the soil to be stored in the interstices between soil particles.  when spaces are filed with water, air is driven out = waterlogged soil (days after water is drained away under gravity until drainage rate is slight/zero-stage of soil is now referred to as being at field capacity  below field capacity plants cannot extract water from the soil=wilting point Soil Analysis Methods in Determining Soil Moisture 1. Gravimetric Methods  most reliable method of estimating soil moisture a. volume of soil is removed from the desired depth and weighed b. volume is then heated until all moisture has been evaporated and the "dry weight" is obtained 2. Neutron Scattering uses radioactive material to measure the soil moisture  the principle is that neutrons given off by a radioactive source slow down according to the concentration of hydrogen atoms in the soil. These hydrogen atoms occur mostly in water so that the number of slow neutrons reaching a detector is correlated with the amount of water in the soil Soil Analysis  Salinity Refers to the accumulation of soluble salts of sodium, calcium, magnesium, and potassium in the soil. The anions found are mostly the chloride and sulfate with some carbonates and bicarbonates these salts have been carried upward by capillarity and have remained when water is evaporated result from intrusion of salt water from the sea when there is excessive withdrawal of fresh ground water it reduces the quality of the soil and its productivity Soil Analysis Pollutants in Soils  soils can retain, modify, decompose or absorb pollutants (atmospheric contaminants, liquid and solid waste)  biodegradable organic materials deposited in the soil are decomposed into safe products (carbon dioxide, methane, nitrogen, and phosphorus)=biogeochemical cycle  due to human activities harmful pollutants gradually accumulates in the soils.  metal mining operations, industrial, agricultural, commercial and domestic activities Soil Analysis Determining Soil Pollutant Gas Chromatography Atomic Absorption Spectroscopy (AAS) Soil Analysis Soil Analysis Soil Analysis Thank you