Lecture 1 Flashcards
age of universe
13.7 +/- -.13 billion years
age of our solar system
4.5 billion
virtually all elements heavier than C have originated from
a supernovae - exploding super-stars from before our sun existed
soils a major source of
microbial diversity
effects of disconnecting form soil
increase in inflammatory diseases and metabolic disorders
average ‘ecological footprint’ of a human in high income countries like ours is ____ ha but there are only ___ha of productive land per person in the world
require 5-10 ha
only 1.9 ha per person
only __% of the earths surface is land & only _% of this area is cultivated with little scope for future expansion
30% is land and only 9% is cultivated
whole of our food production is coming off of a cube =
20 x 20 x 20 km = 8000 km^3
UK wheat yield trends
increased in previous years but now plateaued
fresh water and soil
soil is the big filter
-97% of available freshwater passes through the soil into groundwater
it is estimated that it takes _ million litres of water to grow a hectare of maize
5 million litres
Pimental et al 2004
soil has a significant role in _____ ecosystem services
almost in all
it has crucial foundational role in at least 9 of these
-without soil well lose almost all ecosystem services
soil ecosystem services
1) Food production
2) fresh water
3) fibre
4) wood
5) fuel
6) carbon & nutrient storage
7) climate regulation
8) waste detoxification & pollution control
9) host biodiversity & support biodiversity of above-ground ecosystems
soil loss curve
Church 2010
– same pattern as global warming, exponential growth in soil loss
a cm of top soil typically takes ____ to form
> 200 years to form
–yet it can be swept away in a few seasons.
most of the organic matter and fertility of soil is concentrated in ____ of soil
in the top 20cm (the topsoil)
each year we lose __ billion trees and __ billion tonnes of fertile soil
15 billion trees and 24 billion tonnes of fertile soil
for every person on the planet _ trees are lost and more than __ tonnes of soil is eroded each year
2 trees & more than 3 tonnes of soil
nearly __% of the worlds arable topsoil lost to erosion or pollution in the last 40 years
33%
global soil erosion is increased by __% by human activity
60%
revised universal soil loss equation =
A = R x LS x K x C x P
A= potential annual soil erosion R = Rainfall erosivity LS = slope length & steepness factors K = soil erodibilty C = cropping and management P = soil conservation practices to reduce erosion losses
main anthropogenic causes of soil erosion
- Cultivation (tillage, bare soil, crops with small roots, compaction)
- overgrazing
- deforestation
- salinization - salt pollution from poor irrigation
europe soil formation rates inc dust depositions range from
0.3-1.4Mg (tonnes) ha-1 yr-1
nearly __ the UK for comes from international sources
half
china annual loss of soil
7 km^3 per year
croplands are losing soil at an average rate of nearly 28 tonnes per ha per year
nearly a billion tonnes of soil lost each year in the EU __% of this is from ___ land with a mean rate of __ tonnes per ha
68%
agricultural
3.24 tonnes per ha
soil degradation issue:
- loss of soil quality (loss of organic matter, salinisation, loss of nutrients, infertility)
- loss of soil quantity
loss of quality often increases risks of loss of quantity too
eroded soil __ up rivers and degraded soil stores less ___ increasing flood risks
silts
water
globally soil degradation costs
about 10 trillion US dollars a year (2015)
___ is the most profitable arable crop in the UK
Wheat
- farmers only get 3.9% of supermarket price
- 25-fold increase
is there national data looking at soil health +depth and erosion
lacking in the UK, Sweden better samples
