4. nutrient cycling

7/25/2019 4. Nutrient Cycling

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Material & Nutrient Cycles

1. Nutrient requirements2. Biogeochemical cycles


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Nutrient Requirements for Plant Growth

Taen u! in gaseous form" #$ygen %#2" Car'onC#2" an( from roots ) *ater %+2#.

,eri-e( from water an( car'on (io$i(e

Rest are taen u! from soil solutions

Macro)nutrients Nitrogen %N" Phos!horous

%P" Potassium %/"

Calcium %Ca" Magnesium %Mg" 0ulfur %0

Micro)nutrients Boron %B" Co!!er %Cu" ron%e" Manganese %Mn" Moly'(enum %Mo"

3inc %3n


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Biogeochemical Cycling

The cycling of nutrients through

ecosystems -ia foo( chains an( foo(

we's" inclu(ing the e$change of nutrients'etween the 'ios!here an( the

hy(ros!here" atmos!here an( geos!here

%e.g." soils an( se(iments


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Ecosystems produce and process energy

primarily through the production and exchange

of carbohydrates which depends on the carbon

cycle.

Once energy is used it is lostto the ecosystem

through generation of heat

!arbon is passed through the food chain

through herbi"ory predation and

decomposition it is e"entually lost to the

atmosphere through decomposition in the formof !O2and !#4. $t is then re%introducedinto

the ecosystem "ia photosynthesis.

#owe"er the amount of carbon present in a

system is not only related to the amount of

primary production as well herbi"ory andpredation &e.g. secondary production' it is also

dri"en by the rates of decomposition by micro%

organisms

(tmospheric carbon is rarely limiting to plant

growth


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Ty!es of Biogeochemical Cycles

Three ma4or categories of 'iogeochemical

cycles 'ase( on slowest)changing

!ool%5reser-oir6

1. Gaseous cycles of C" #" +27

2. Gaseous cycle of N" %0

8. 0e(imentary cycles of the remaining nutrients

Glo'al scale

9ocal scale


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0e(imentary Cycles

Gaseous Cycles


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Ma4or Com!onents of Nitrogen Cycle


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Biological Nitrogen i$ers

Cyano'acteria 'lue)green algae

ree li-ing soil 'acteria

Mycorrhi:ae

0ym'iotic 'acteria li-ing in root

no(ules


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oot nodules on Cassia fasciculata


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Phos!horous Cycle

Phos!hate P#;)8


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*ater !ycle

E(5O(,$O6

,(675$(,$O6

!O68E67(,$O6

5E!$5$,(,$O6

96 O:: O E,96E8


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!(;O6 !


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Tree Nutrient Content

7.12;?ucaly!tus

7.1Tem!erate

,eci(uous

7.1777.7;87.1;


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uestion (o !lants growing on sites

with low soil nutrients ha-e low

nutrient contents as well

The answer is no

Plants on sites with low nutrients ten( to

ha-e higher nutrient contents

They ha-e a higher nutrient use efficiency


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actors nfluencing

Nutrient D-aila'ility

Presence of nitrogen fi$ers

Micro'ial acti-ity

ire

Preci!itation !atterns

0oil (rainage 0oil tem!erature" moisture

4. nutrient cycling

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