bio1ps201201

Australian Soils

Generally nutrient-poor

Very ancient soils

•long periods of erosion and leaching

•no recent geological processes such as volcanic, glacial or alluvial activity to build up ‘new’ soil rich in nutrients

•low biological activity (because hot and dry)

•very low in phosphate

Compare with very fertile soils in Java

•current volcanic activity

•heavy rains (alluvial activity)

•year-round biological activity

•supports large human population (100 million)

C, N, and P Cycles

•All the nutrient cycles are based in soil

•Pools of all nutrients on earth are limited

•Constant recycling necessary in order to provide nutrients to support continued life on earth

Knox p 357, 1185-1193

C, N, and P Cycles

Carbon

•woody structures of vegetation (cellulose!)

•must be recycled to provide CO2 for ongoing

photosynthesis	C in forest biomass: 288.8 billion t
Nitrogen	Global Forest Resources Assessment 2010

•proteins etc. in plants and animals

•must be recycled to give the N salts required by plants

Phosphorus

•

•

ATP, nucleic acids

easily immobilised in soil

Carbon Cycle

C Cycle Animation:

http://vro.dpi.vic.gov.au/dpi/vro/vrosite.nsf/pages/soilhealth_organic_carbon-cycle

Ladiges et al. (2010), 4th ed., Fig. 44.19

Nitrogen Cycle

N Cycle Animation:

http://vro.dpi.vic.gov.au/dpi/vro/vrosite.nsf/pages/soilhealth_nitrogen-cycle

Ladiges et al. (2010), 4th ed., Fig. 44.20

Phosphorus Cycle

Ladiges et al. (2010), 4th ed., Fig. 44.22