1

Effects of Desertification on the Productivity of the Natural

and Agro-ecosystems: Consequences and Solutions

Convention to combat

desertificationLand degradation

Climatic changesHuman activities

Agro-ecosystems

Wind and water erosion

SalinizationWaterlogging

Drylands

Hyper-aridAridSemi-arid

2

5034

Sand dune encroachment

Humid environments

Deforestation

Unproductive deserts 9

80

Waterlogged

11.5

Carbon

sequestration

Arable lands

Highly variable rainfall

Scarcity of water resources

Agricultural intensification

1

Wild firesOvergrazing

3

2

HeatDroughtSalinity

Abiotic factors

1

Root systems

Source size

Transpiration

Evaporation

Well-branched deep root system

4

Turgor potential

2

Protective systems

Photoinhibition

3 WUE

Capacity types

Grain fill

Photo-assimilates

4

End- product effect

CO2-enrichment

5

1971

5

1

27Wheat42 Barley

Water use efficient cultivars

Water

productivity

EvaporationProductive transpiration loss

Contour ridging

Mulch

6

1

65

65

1 59

65

60

60

60

357 107 885 2 68

68

1103

1103

2 899

176

176

176

176

1105 1 901 4 1230

1107 1107 969

1164

1169 5 1119 2 1420

7

1119 1 1097 1 1500

1229 3 981

1245

1069

Intensive marginal

agricultural systemsRangeland areas

Technically feasible

Socially acceptableSustainable

Reverse

2

8

110Surface run-

9

offDeep drainage Evaporation

Transpiration

Weeds

Soil moisture content

Capture

Water

infiltration

1

2 Reseeding degraded rangelands

3 Fodder shrubs and trees

4

Pits

10

Degraded calcareous soils

Seedling establishment

Wind erosion

Intensive fallow system

Cereal monocropping

Soil fertility

Wind erosion

Vetches

(Vicia spp.)(Lathyrus spp.) Chcklings

Mediterranean

basin

Hay

Straw

Small ruminant flocks

Crop residues

11

CO2Intensive tillage

3050

Sustainable land productivityTillage

Carbon sequestration

1998Paustian et al.,

400900MMTCE

1997Lal15

(SOC) Soil organic carbon

200 MMTCE

Soil erosion

Soil Temperature regulation

12

No-tillage

Lal, 1997; Paustian et al., 1997b

CO2-sequestration

Yield gapFood gap

1Wheat

Conservation agriculture1136.55

11087.55

1

10.04

2Rainwater use efficiency

4.261

3.141

13

1

2

39251

3290

1350

1400

1450

1500

1550

1600

1650

الزراعة الحافظة الزراعةالتقليدية

ة جي

تاإلن

اطس

توه

(غك

/ار

كته

)

نظام الزراعة

الزراعة الحافظة الزراعة التقليدية

Series1 4.26 3.14

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

ر طا

لواال

ه يا ه

العو

ست اءة

فاك

(غك

/(هن

14

.1

18.723

3

4

4

الزراعة الحافظة الزراعة التقليدية

Series1 3925 3290

2800

3000

3200

3400

3600

3800

4000

ر عي

ش ال

يةجتاإنط

ستو

ه(

غك

/ار

كته

)

02468

10

الزراعة الحافظة الزراعة التقليدية

Series1 9.2 7.48

ر طا

لو ال

اههي

ل وا

تعس

اءة

فاك

(غك

/(هن

15

Evaporation

Organic matter

Aggregate size and stabilitySoil porosity

11051

Seed dressing

N 9% + P 15%

18Zn+2

6Cu+2

27.4Mn+2

5

Seeding rate

6912

1Weed control

Weeds

11051121

16

405.211

61

214.201

5.52

10.19

12112.94

Evaporation

More crop per drop

Water harvesting and irrigated agriculture:

Cisterns

17

Micro-

catchment techniques

Artificial storage structures

Macro-catchment techniques

Supplemental irrigation

Topography

Run-off coefficient

Shallow aquifers

Water

extractionRecharge

Sea water intrusion

18

Judicious application

250

200

0.54.0500

701.5

2

0.5

19

References

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Dubai. Taylor & Francis. 489 pages.

Discussion paper. ICARDA.

El-Beltagy, A. 1997. West Asia and North Africa: A Regional

Vision. ICARDA-023/400. PP.1-20.

FAO. 1995. FAO STAT. PC. FAO, Rome, Italy.

Farouk El-Baz and M.H.A.Hassan. 1986. Physics of desertification.

International Centre for Theoretical Physics. Springer. 473 pages

Glantz, M. H., and N. S. Orlovsky. 1983. Desertification: A review of

the concept. Desertification Control Bulletin 9: 15-22. Available at

http://www.ciesin.org/docs/002-479/002-479.html.

GreenFacts Digest. "Scientific Facts on

esertification". http://www.greenfacts.org/en/desertification/index.ht

m Last modified in 2006.

http://www.greenfacts.org/en/desertification/l-2/6-prevention-

desertification.htm#3.

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Millenium Ecosystem Assessment. 2005. Ecosystems and Human

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Nichola Geeson, C.Jane Brandt and John B.Thornes. 2002.

Mediterranean desertification: a mosaic of processes and responses.

John Wiley and Sons. 440 pages.

Nordblom, T.L., and Shomo, F. 1995. Food and feed prospects in the

West Asia/North Africa. ICARDA Social Science paper No. 2.

ICARDA, Aleppo, SYRIA.

Oweis, T. 1997. Supplemental irrigation--a highly efficient water-use practice.

ICARDA-037/1000. PP.1-16.

20

Rodriguez, A. 1997. Poverty and natural resources management in dry areas.

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Drylands". http://www.fao.org/docrep/007/y5738e/y5738e06.htm

Accessed 08 June 2010.

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