4.1 Soil properties and their influence on infiltration
3 min read•july 22, 2024
Soil properties play a crucial role in infiltration, the process of water entering the ground. Texture, structure, and porosity influence how quickly water moves through soil. Understanding these factors helps predict water movement and storage in different soil types.
Soil moisture and also affect infiltration rates. Initially dry soils absorb water faster, but rates decrease as soil saturates. and can significantly reduce infiltration, highlighting the importance of proper soil management practices.
Soil Properties and Infiltration
Key soil properties for infiltration
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Top images from around the web for Key soil properties for infiltration
Soil Texture and Structure – Soils Laboratory Manual View original
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Determining Soil Texture | OER Commons View original
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refers to the relative proportions of sand, silt, and clay particles in a soil
Sandy soils have larger pore spaces between particles allowing for faster infiltration (beach sand)
Clayey soils have smaller pore spaces resulting in slower infiltration (pottery clay)
Soil structure is the arrangement of soil particles into aggregates
Well-structured soils have more stable aggregates and larger pore spaces facilitating better infiltration (crumbly topsoil)
Poorly structured soils have less stable aggregates and smaller pore spaces reducing infiltration rates (compacted subsoil)
represents the percentage of soil volume occupied by pores or spaces between particles
Higher porosity allows for more water storage and faster infiltration (pumice rock)
Lower porosity restricts water movement and reduces infiltration rates (granite rock)
Soil moisture and hydraulic conductivity
refers to the amount of water present in soil pores
Initially dry soils have higher infiltration rates due to and available pore space (desert soil after a dry spell)
As soil becomes saturated infiltration rates decrease (soil after heavy rainfall)
Hydraulic conductivity measures a soil's ability to transmit water
Depends on soil texture structure and pore size distribution
Higher hydraulic conductivity allows for faster water movement and infiltration (gravel)
Lower hydraulic conductivity restricts water flow and reduces infiltration rates (clay)
Soil characteristics vs infiltration capacity
is the maximum rate at which soil can absorb water and varies based on soil properties and initial moisture content
Soil texture: sandy soils generally have higher infiltration capacities than clayey soils (sand dunes vs clay plains)
Soil structure: well-structured soils have higher infiltration capacities due to larger pore spaces (healthy grassland vs overgrazed pasture)
Soil porosity: higher porosity allows for greater infiltration capacity (volcanic ash vs hard pan layer)
: initially dry soils have higher infiltration capacities than wet soils (soil after a dry summer vs soil in the rainy season)
Infiltration capacity changes over time
Decreases as soil becomes saturated and pore spaces fill with water
Reaches a constant rate when soil is fully saturated
Impact of compaction on infiltration
Soil compaction is the reduction in soil pore space due to external pressure
Caused by heavy machinery livestock or human traffic (construction sites animal feedlots hiking trails)
Decreases infiltration rates by reducing pore size and hydraulic conductivity
Surface sealing is the formation of a thin low-permeability layer on the soil surface
Caused by raindrop impact fine particle deposition or chemical dispersion (bare agricultural fields after rainfall)
Reduces infiltration rates by limiting water entry into the soil
Management practices to mitigate compaction and surface sealing include:
Minimize soil disturbance and compaction during wet conditions
Use conservation tillage or no-till practices to maintain soil structure (cover crops crop residue management)
Maintain surface cover to protect soil from raindrop impact (mulch plant litter)
Incorporate organic matter to improve soil structure and porosity (compost manure)
Key Terms to Review (10)
Antecedent Moisture Content: Antecedent moisture content refers to the amount of water present in the soil before a precipitation event occurs. This existing moisture level plays a crucial role in influencing infiltration rates, as soils that are already saturated will absorb less additional water compared to drier soils. Understanding antecedent moisture content is essential for predicting how much rainfall will infiltrate the ground versus becoming surface runoff.
Capillary Forces: Capillary forces are the forces of attraction between liquid molecules and solid surfaces, which play a crucial role in the movement of water through porous materials like soil. These forces arise due to the surface tension of water and the adhesive forces between water and soil particles, enabling water to move upward or laterally against the force of gravity, particularly in unsaturated soils. Understanding capillary forces is essential for grasping how water interacts with soil, influencing both infiltration rates and vadose zone hydrology.
Compaction: Compaction refers to the process by which soil particles are pressed together, reducing the volume of pore spaces between them. This process can significantly affect the physical properties of soil, including its density and porosity, which in turn influence water infiltration rates. The degree of compaction can alter the movement of water through the soil, impacting how much water is absorbed and how quickly it moves through the ground.
Hydraulic Conductivity: Hydraulic conductivity is a measure of a material's ability to transmit water through its pores or fractures, crucial for understanding groundwater flow and its interaction with surface water. It relates to aquifer properties, influencing how quickly water can move through soil and rock, which is essential for managing groundwater resources and recharge processes.
Infiltration Capacity: Infiltration capacity refers to the maximum rate at which water can penetrate into the soil surface, influenced by various factors like soil texture, structure, moisture content, and land use. Understanding infiltration capacity is essential as it directly affects water availability, runoff generation, and groundwater recharge, playing a significant role in the overall hydrologic cycle.
Infiltration Rate: Infiltration rate is the speed at which water enters and moves through the soil surface and into the ground. This process is vital for understanding how water interacts with the land, impacting groundwater recharge and the overall hydrologic cycle. Factors like soil texture, structure, moisture content, and vegetation play a significant role in determining how quickly water can infiltrate, affecting everything from flood risk to water supply.
Soil Moisture Content: Soil moisture content refers to the amount of water contained within the soil, expressed as a percentage of the soil's weight or volume. It plays a crucial role in plant growth, water availability, and hydrological processes, influencing how water moves through the soil and interacts with the atmosphere. Understanding soil moisture content is essential for grasping how it affects processes like evapotranspiration and infiltration, which are vital for maintaining ecosystems and agricultural productivity.
Soil Porosity: Soil porosity refers to the volume of empty spaces or pores within a soil sample compared to its total volume. This characteristic is crucial as it affects how much water and air can be held in the soil, influencing both infiltration rates and the overall health of the ecosystem. Higher porosity often leads to better drainage and aeration, while lower porosity can contribute to waterlogging and poor plant growth.
Soil Texture: Soil texture refers to the relative proportions of different particle sizes in a soil, specifically sand, silt, and clay. This characteristic influences various soil properties, including porosity, permeability, and water retention, which play vital roles in infiltration processes. Understanding soil texture helps predict how water moves through soil and how it interacts with the surrounding environment.
Surface sealing: Surface sealing refers to the formation of a layer on the soil surface that restricts water infiltration, often caused by compaction, crusting, or the accumulation of organic matter. This layer can significantly hinder the movement of water into the soil, leading to increased runoff and reduced groundwater recharge. Understanding surface sealing is crucial as it affects the overall hydrological processes, influencing both water availability and soil health.