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Field capacity is the maximum amount of water that soil can hold without any drainage.
Field capacity is the maximum amount of water that soil can hold without any drainage.
True
Water movement in soil due to gravitational pull becomes significant after the soil reaches field capacity.
Water movement in soil due to gravitational pull becomes significant after the soil reaches field capacity.
False
The permanent wilting point is the amount of water remaining in soil when a plant is fully hydrated.
The permanent wilting point is the amount of water remaining in soil when a plant is fully hydrated.
False
Soil water management is essential due to the worldwide issue of water deficiency in agricultural production.
Soil water management is essential due to the worldwide issue of water deficiency in agricultural production.
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It is easy to replicate field capacity conditions in a laboratory setting.
It is easy to replicate field capacity conditions in a laboratory setting.
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PWP indicates that water is still available to plants for absorption.
PWP indicates that water is still available to plants for absorption.
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Water moves through soil at a slow rate once field capacity is reached.
Water moves through soil at a slow rate once field capacity is reached.
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A soil's field capacity can be measured by providing it with water until it is fully saturated.
A soil's field capacity can be measured by providing it with water until it is fully saturated.
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Tensiometers are effective in measuring soil moisture suctions up to 1.2 bars.
Tensiometers are effective in measuring soil moisture suctions up to 1.2 bars.
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Time Domain Reflectometry (TDR) measures the travel time of sound waves along metal rods.
Time Domain Reflectometry (TDR) measures the travel time of sound waves along metal rods.
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Most plants obtain 70% of their moisture requirements from the upper half of the rooting zone.
Most plants obtain 70% of their moisture requirements from the upper half of the rooting zone.
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The speed of electromagnetic waves in TDR is independent of the soil water content.
The speed of electromagnetic waves in TDR is independent of the soil water content.
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Tensiometers are used in environments like orchards and nurseries.
Tensiometers are used in environments like orchards and nurseries.
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Measurements with TDR are localized and extend several meters from the inserted rod.
Measurements with TDR are localized and extend several meters from the inserted rod.
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Water flows in a homogeneous soil primarily due to gravity.
Water flows in a homogeneous soil primarily due to gravity.
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Soil moisture probes should ideally be placed deeper than 1 meter for effective irrigation.
Soil moisture probes should ideally be placed deeper than 1 meter for effective irrigation.
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The weight of dry soil that was wetted can be calculated using the formula: $Weight\ of\ wet\ soil \times\ bulk\ density$.
The weight of dry soil that was wetted can be calculated using the formula: $Weight\ of\ wet\ soil \times\ bulk\ density$.
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The percent water at field capacity is calculated by dividing the weight of water added by the weight of soil wetted and multiplying by 100.
The percent water at field capacity is calculated by dividing the weight of water added by the weight of soil wetted and multiplying by 100.
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Resistance blocks can measure moisture content in soils with high moisture levels effectively.
Resistance blocks can measure moisture content in soils with high moisture levels effectively.
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The simple gravimetric method requires weighing a moist soil sample before and after drying it at temperatures exceeding 105°C.
The simple gravimetric method requires weighing a moist soil sample before and after drying it at temperatures exceeding 105°C.
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Tensiometers are used primarily for measuring soil moisture in areas with frequent irrigation.
Tensiometers are used primarily for measuring soil moisture in areas with frequent irrigation.
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The weight of the aluminum container is 31.32 g.
The weight of the aluminum container is 31.32 g.
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The mass of the oven dry soil is recorded as 40.96 g when weighed with the aluminum container.
The mass of the oven dry soil is recorded as 40.96 g when weighed with the aluminum container.
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Water movement in unsaturated soil occurs when there is free water present in the soil.
Water movement in unsaturated soil occurs when there is free water present in the soil.
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Stratified soil affects water flow due to the varying sizes of pores in different layers.
Stratified soil affects water flow due to the varying sizes of pores in different layers.
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Sandy loam has a greater wetting depth than clay when the same amount of irrigation water is applied.
Sandy loam has a greater wetting depth than clay when the same amount of irrigation water is applied.
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The pH level of soil can affect the solubility of nutrients necessary for plant growth.
The pH level of soil can affect the solubility of nutrients necessary for plant growth.
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The wetting depth of sand is less than that of loam when irrigated with the same amount of water.
The wetting depth of sand is less than that of loam when irrigated with the same amount of water.
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PH is measured as the positive logarithm of H+ ion activity in soil solutions.
PH is measured as the positive logarithm of H+ ion activity in soil solutions.
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Aggregation of soil can influence infiltration rates when water is applied.
Aggregation of soil can influence infiltration rates when water is applied.
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A soil with a high pH is considered to be alkaline.
A soil with a high pH is considered to be alkaline.
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Soil pH only reflects the reserve acidity in an acid soil.
Soil pH only reflects the reserve acidity in an acid soil.
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Electrometric determination of soil pH requires standardization against buffer solutions of known pH.
Electrometric determination of soil pH requires standardization against buffer solutions of known pH.
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The optimal soil pH for maximum nutrient availability is generally around 5.5.
The optimal soil pH for maximum nutrient availability is generally around 5.5.
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A distilled water extract measures both active and reserve acidity in the soil.
A distilled water extract measures both active and reserve acidity in the soil.
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PH influences microbial activity and nutrient availability in mineral soils.
PH influences microbial activity and nutrient availability in mineral soils.
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Active acidity can be altered by the addition of either water or a salt solution.
Active acidity can be altered by the addition of either water or a salt solution.
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Weak acid groups associated with soil organic matter remain unaffected by dilution.
Weak acid groups associated with soil organic matter remain unaffected by dilution.
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The recommended concentration of CaCl2 to represent normal soil solution salinity is 0.01 M.
The recommended concentration of CaCl2 to represent normal soil solution salinity is 0.01 M.
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The use of a potentiometer is not necessary in electrometric soil pH measurement.
The use of a potentiometer is not necessary in electrometric soil pH measurement.
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The pH measurement should only be conducted with distilled water and not with CaCl2 for accurate results.
The pH measurement should only be conducted with distilled water and not with CaCl2 for accurate results.
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Soil samples for pH measurement should weigh 5 grams and be added to 35 ml vials.
Soil samples for pH measurement should weigh 5 grams and be added to 35 ml vials.
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The total time to measure the pH after preparing the soil solution is 30 minutes.
The total time to measure the pH after preparing the soil solution is 30 minutes.
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Colorimetric determination of soil pH is considered more complex than other methods.
Colorimetric determination of soil pH is considered more complex than other methods.
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PH-sensitized paper can provide a rough estimate of soil pH by matching color changes to a chart.
PH-sensitized paper can provide a rough estimate of soil pH by matching color changes to a chart.
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Two systems for measuring soil pH currently use either distilled water or a series of color indicators.
Two systems for measuring soil pH currently use either distilled water or a series of color indicators.
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The soil series should not be mixed when graphing the pH values obtained from different solutions.
The soil series should not be mixed when graphing the pH values obtained from different solutions.
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Study Notes
Soil Water
- Soil water is a crucial component in agriculture, often the limiting factor globally.
- Water availability varies, sometimes deficient, other times surplus.
- Managing soil water requires understanding soil properties affecting water retention and movement.
- Two vital measurements are field capacity and permanent wilting point.
Field Capacity (FC)
- Field capacity is the water held in the soil 2-3 days after saturation, from rainfall.
- This period allows water movement downwards via capillary action and gravity.
- Gravitational pull becomes negligible, and capillary movement slows.
- A fairly constant moisture content is achieved in the top soil layers - this is field capacity.
- Field capacity is the maximum attainable water content under normal agricultural conditions.
- Duplicating these conditions in a lab is difficult.
- Measuring field capacity involves filling a container with soil, saturating, and letting it drain for a week, then sampling moisture.
Permanent Wilting Point (PWP)
- Permanent wilting point is the amount of water remaining in the soil when a plant wilts in a high-humidity environment.
- Plants cannot absorb water below this point, losing turgidity.
- Temporary wilting can occur in moist soil when transpiration exceeds water absorption capacity.
- This wilting reverts when humidity/temperature changes.
- Available water is the water between field capacity and permanent wilting point, usable by plants for transpiration.
- Multiplying the gravimetric moisture percentage by the bulk density gives the available water volume.
Soil Water Constants
- Hygroscopic water content is another important constant.
- This water is held tightly by soil particles only moving in the vapor phase, it’s unavailable to biological life.
- The amount depends on the soil particle surface area. Air-dried soils retain hygroscopic water.
- Important for crop growth that the soil moisture is above the permanent wilting point.
Experiments
- Experiment 1: Capillary Action in Soils
- Experiment 2: Field Capacity
- Experiment 5: Hygroscopic Water
Additional Information
- Rooting depth varies depending on water supply and soil type.
- For crop growth, sufficient water is crucial, but exceeding field capacity is inefficient.
- If soil dries out before sufficient water is available, shallow-rooted plants will be affected.
- Deep-rooted plants are better adapted to arid conditions.
- Methods for measuring soil water content include gravimetric method, resistance blocks, tensiometers, and time domain reflectometry (TDR) methods.
- These procedures vary based on the conditions like dry soil/irrigated soil, homogenous/stratified soil etc.
- Different methods measure different aspects of water content in soils (e.g., available water or hygroscopic water).
- Soil pH measurements.
- Soil pH values are measured using a pH meter or colorimetrically with indicator dyes.
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Description
This quiz explores the essential concepts of soil water management, focusing on field capacity and its significant role in agriculture. Understanding the measurement techniques and the importance of moisture retention is crucial for effective farming practices. Test your knowledge on these vital agricultural principles.
