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Loss of resources

In the world as a whole about 25000 million tones of soil are being washed away from land every year. In India, the figure is 6.25 thousand million tones. Due to erosion and degradation, the world is losing between 5-7 million ha of cultivated land every year which is nearly the same as the new land brought under cultivation, which means that the extent of cultivated land remains more or less same (Lazarus, 1992). According to Millennium Ecosystem Assessment (MA) Report about 1020

per cent of world drylands are degraded accounting about 6-12 million km2 (MA, 2005). Drylands in India contribute to over 70 per cent of the total cultivated area and about 50 per cent of the total geographic area is affected by desertification (Hegde, 2006). Land degradation is particularly problematic for both environmental sustainability and poverty reduction in dryland areas. The UN Convention to Combat Desertification (UNCCD) and others use ''desertification'' to describe dryland degradation which is caused due to several factors including climatic variations and human activities. Depending on the level of aridity, dryland biodiversity is relatively rich, still relatively secure and is critical for the provision of dryland services. Of 25 global ''biodiversity hot spots'' identified by Conservation International, 8 are in drylands. So to conserve dryland are very important to ensure food security, conserve rich biodiversity of drylands and improve livelihoods of dryland people. To conserve the scarce resources of drylands a number of practices or methods are used which constitute dryland conservation technologies. These technologies are agronomic or cultural practices like conservation tillage, mulching, organic manure application, contour faming, strip cropping, use of wind breaks, allay cropping, vegetative barriers etc. and mechanical or engineering methods which include basin listing, sub-soiling, terracing, contour bunding, contour trenching, use of gully plugs, check dams and water harvesting structures like community tanks, intra terrace water harvesting and roof top water harvesting etc. In spite of these practices or methods there are several other measures which can be applied for dryland conservation. These approaches are :

i. Sustainable farming practices

ii. Precision conservation

iii. Integrated watershed approach, and

iv. Use of agroforestry

Table 2. Drylands of the world

Continents

Land mass (M ha)

Hyper

arid

(<0.05)

Arid (0.5 < 0.20)

Semiarid (0.200.50)

Dry subhumid

(0.50-.65)

% of world drylands

Africa

2965.6

672.0

503.5

513.8

268.7

31.9

Asia

4255.9

277.3

625.7

693.4

352.7

31.7

Australia

882.2

0.0

303.0

309.4

51.3

10.8

Europe

950.5

0.0

11.0

105.2

183.5

4.9

North America

2190.9

3.1

81.5

419.4

231.5

12.0

South America

1767.5

25.7

44.5

264.5

207.0

8.8

Total

13012.6

978.1

1569.2

2305.3

1294.7

100.

% of world drylands

16

26

37

21

[Source : Reynolds and Smith, 2002]

 
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