Soil and Water Conservation Works - Afforestation, Reforestation and Forest Restoration in Arid and Semi-arid Tropics - page 89

Contour Trench

Pits

3 m

Contour Trench

10 to 20 m

Sectional View of Layout

0.50

1.5 m

0.45

3.0 m

1.50 m

0.40

Section of a Pit

Layout of Pits Between Contour Lines

Mound/Berm

Saucer

Sectional View of Saucers

Direction of Slope and

Depth 10 cm

0.30

Flow of Water

↓

Ridge of

0.20

Compacted Soil

0.90

Section of a Saucer and Berm View From Top of a Saucer

Standard Pit Sizes

Volume m 3

Pit No. Size (m) When recommended

P-1
P-2
P-3
P-4
P-5

0.35 x 0.35 x 0.35 0.043 Limited soil depth, thorny plants.

Standard.
Standard.
Easily workable soils, good soil depth.
Avenue and urban area plantations.
High quality plantations; replaced soils.

0.45 x 0.45 x 0.45 0.091

0.091
0.125
0.216
0.562

(0.50,0.40) x 0.45

0.50 x 0.50 x 0.50

0.60 x 0.60 x 0.60
0.75 x 0.75 x 0.75 P-6

Fig. 5.1 Details of planting pits

5.2 Digging of Contour Trench

Continuous contour trench is dug along a previously marked contour line, keeping
the line on the upper edge of the trench so that it is visible even after excavation of
the trench. Sections of the contour line that are not diggable are left out. Only the