Soil Flashcards
What is soil fertility?
The ability for soil to sustain plant growth
Describe water content for fertile soil
Good drainage to prevent water logging but allows enough retention for soil biota to survive.
Describe Soluble Material for fertile soil
Fertile soils have macronutrients like nitrogen and phosphorus as well as micronutrients like copper or iron. Toxic ions are adsorbed so they cannot be mobilised and taken into plants
Describe Air Content in fertile soil
Aerated soil allow aerobic processes to take place, which usually increase fertility
Describe Dead Organic Matter in fertile soil
Dead organic matter helps water retention and provides food for soil biota and nutrients for plants.
Describe pH in fertile soil
Usually in the range of 5.5-7.0, avoiding acidic conditions that can damage membranes and alkaline conditions that can deny nutrients
Describe soil biota in fertile soil
- Detritivores break up dead organic matter and increase nutrients
- Decomposers release enzymes that break down organic matter
- Several bacteria types interact with nitrogen
- Mycorrhizal fungi aid nutrient uptake of plants
What is the soil triangle?
Coolest thing in env sci
What type of soil has the largest particles?
Sand
What type of soil has the smallest particles?
Clay
What is a loam?
Soils with a fairly equal mix of clay, sand and silt that have an ideal mix of properties for agriculture
What are peds? What are the two types?
A ped is soil particles held together by roots, soil biota or other factors.
Crumb peds are small and round and have good drainage and aeration.
Platy peds are large and flat and have bad drainage and aeration.
How does soil depth affect fertility?
Deeper soils are more stable in water content and allow good root anchorage.
How can ploughing affect soil fertility?
Increases the air content of the soil
How can we affect soil nutrient levels?
- Fertilisers
- Supporting natural processes
- Erosion
- Biomass removal
- Inhibiting natural processes
What benefits does Irrigation have for soil fertility?
increases water content allowing plants to keep their stomata open to do gaseous exchange during normally dry periods
What can cause soil compaction?
Heavy machinery and livestock
What are the two types of erosion?
Wind and water
What conditions can increase risk of wind erosion?
Dry climate and high-clay soil reducing particle cohesion.
What issues can wind erosion cause?
Reduces soil levels in area, increases soil level elsewhere and can cover plants
What are the 3 types of water erosion?
- Rain splash
- Runoff
- Slumping
Why does Rain Splash erosion take longer?
Each drop of rain only causes loose soil particles to move slightly, so even downhill movement takes time
What condition allows for Runoff erosion?
When soil has reached it maximum infiltration capacity
How does slumping erosion work?
When soil on slopes becomes wet its mass and lubrication increases leading to it making large downward movements
What issues can slumping erosion cause?
deforestation and destruction of habitats or individuals
How can erosion naturally be reduced?
Vegetation can act as a windbreak, impact reducer, particle binder and increases the amount of water able to be held by soil
Name human activities that can increase erosion
- Vegetation removal
- Ploughing
- Overgrazing
- Compaction of soil
- Agrochemicals reducing soil biota
- Slope cultivation
How can we reduce soil erosion rates?
- Long term crops
- Zero-tillage cultivation
- Contour ploughing
- Terracing
- Windbreaks
- Multicropping
- Increasing soil organic matter with mulch
- Livestock management
What effects can accelerated soil erosion have?
- Reduced productivity
- Sedimentation in nearby water bodies
- Increased atmospheric particulates
- Desertification
What does USLE stand for? What does it do?
The Universal Soil Loss Equations which can be used to estimate soil loss and impact of farming technique
What are the 7 factors in the USLE?
- Rate of soil erosion
- Rainfall susceptibility/erosivity
- Erodibility factor
- Slope length
- Slope gradient
- Crop management factor
- Erosion control factor
What are the 5 Soil Erosion classes and what USLE score do they each have?
Very Low = <5.0 USLE
Low = 5.1 - 10.0 USLE
Moderate = 10.1 - 20.0 USLE
High = 20.1 - 30.0 USLE
Severe = >30.0
