Phosphorus Flashcards
(7 cards)
Eutrophication costs
Damage costs - drinking water treatment $26.6m
Loss of key/ sensitive species $10 -14.7 m
Policy response costs $77
Fraction of agri’s contribution to total economy gross = 1.6-2.1%
The p problem: when is P expected to peak? How efficient is P uptake for a) plants b) livestock
2030
a) 60%
b) 16%
Soil erosion on site and off site effects
On site:
- soil redistribution and loss
- breakdown of soil structure
- loss of matters and nutrients
- decrease in soon moisture availability
- decrease in soil cultivated depth
- decrease in soil fertility
Off site:
- sedimentation -> increase flood risk, blocked irrigation canals
- effects on ecology -> periphyton and macrophytes -> decrease in biomass, abrasive damage, decrease in abundance and diversity of invs, clogs gills and gut, salmanoids -> increase mortality of eggs and young, decrease growth, and feeding efficiency, physical damage to gills
- soil carbon released into amos globally = 1.14 x 10^15 gC yr-1
(Morgan, 2005)
Costs of soil erosion for Uk and US
UK : 90m /yr - 1.26% of agri’s contribution to total economy gross
US : $30-40 billion
Sources
Woodland Improved and unimproved grassland Arable land Roads and urban areas STW Mining and quarrying
Soil erosion mobilisation and transport
- Detachment via:
- rain splash
- weathering
- tillage and farm traffic - Transport via:
- overland flow (majority)
- rills, gullies
- increased by tramlines, macropore flow and drain flow
In water:
Suspended and bed load
- Deposition
- when flow decreases e.g. inside meanders or drier periods
But can be remobilised
Soil erosion - influencing factors
Rainfall erosivity = f(intensity, duration, drop-size distribution)
Soil erodibility = f(texture, aggregate, stability, shear strength, infiltration capacity, org and chemical content)
Also compaction
Antecedent soil moisture
Slope
Plant cover
