Glossary - Afforestation, Reforestation and Forest Restoration in Arid and Semi-arid Tropics - page 273

Rotational grazing Grazing in different areas by turn, usually in different years or
seasons. It reduces grazing pressure in the area and allows time for regeneration of
grasses and legumes.

rotodynamic pump A water pump which forces water with rotating impellers.

RSC ⇒ Residual sodium carbonate

Runoff The portion of precipitation on land that ultimately reaches streams. Steep
slope and hard impervious soils lead to a greater runoff, and also to greater erosion.

Runoff prediction Estimating the runoff resulting from a given tract of land in a
given storm of precipitation. Methods of runoff prediction often use formulae based
on empirical observation and some basic assumptions.

S ⇒ siemens

Saline soil Soil containing excess of sodium salts, especially sodium chloride and
sodium sulphate, usually occurring in depressions. On drying up, these lands show
white efflorescence, giving them the common name 'white alkali'. These soils may
be devoid of vegetation or may bear a restricted class of plants known as halophytes.
⇒

Alkaline soil

Salinity The extent of salts, especially of the alkali metals and magnesium, in
water or soil. Salinity as concentration of salts is measured in terms of the electrical
conductivity of such water or soil, often expressed in terms of mS / cm 2 .

Sand dune stabilisation Developing vegetative cover of trees, shrubs, and grasses
on sand dunes to check movement of sand and to make the land productive.

SAR ⇒ Sodium absorption ratio

Saucer A small shallow depression in shape of a saucer with a peripheral ridge
made of soil, around a plant. It is meant to harvest rain water and to hold water close
to the plant, so as to enable the plant to grow better in the water-deficient conditions
of arid and semi-arid areas.

Secateurs Pruning shears or cutters with narrow blades but powerful leverage to
allow cutting of thick branches.

Seedbed ⇒ Bed

Seed treatment The operation of softening, scarifying, or cracking the seed coat for
easy and quick germination. Seeds of many species have very hard seed coat which
may not break or whither for a very long time, thus leading to delayed germination.
The usual methods prescribed for treatment of such seeds before sowing include
soaking of the seeds in boiled water or in sulphuric acid, mechanically scarifying
the seeds, burying the seeds in a pit covered with moist soil or slurry, and alternate
wetting and drying in the open.
Seed viability The period over which the seed will retain its germinating capacity
within specified limits.