Nursery Techniques - Afforestation, Reforestation and Forest Restoration in Arid and Semi-arid Tropics - page 16

Table 2.1 Quality parameters for water suitable for use in nursery
Parameter Safe limits

Alkalinity or acidity (pH value) 6.5-7.5; though a great deal depends upon the

nature and pH of the soil

Salinity (total dissolved solids (TDS)):
electrical conductivity (EC) value in mS/cm 2

0.75 or less is standard; up to 2.25 in soils with
good drainage or with salt-tolerant species

Sodium absorption ratio (SAR) 10 or less; more problematic in soils with high

cation exchange capacity (fine-textured soils)

Boron cations 0.50 ppm or less; though concentration in the

range of 0.03-0.05 ppm is desirable for
normal plant growth

Residual sodium carbonate (RSC) 2.50 mEq/l, though 1.25 mEq/l is perfectly safe

for all situations

and soil. Accordingly, the quality stringency of water will depend upon the plant
species used in afforestation and also upon other factors such as presence or absence
of salinity in soils of the plantation site (Table 2.1 ). Water with salinity less than 0.75
mS/cm 2 will suit most of the species commonly used in arid zone afforestation.
The terrain that suits a nursery best is a gently sloping terrain, or a flat terrain as
a second choice. Steep slope should be avoided because it involves greater costs in
terms of terracing and levelling of the ground. Area required depends upon size of
nursery (its capacity in terms of plant production per season) and also upon whether
large-scale growing fields (mother beds) will be used for producing tall plants. How-
ever, for a nursery of 100,000-300,000 plants—to be raised primarily in polypots—
an area of 1 ha will be sufficient.
A nursery should be provided with a cattle-proof fence. If wild animals like blue
bulls ( Boselaphus tragocamelus ) are present in the area, they might even jump the
fence and destroy the plants. Therefore, choice of fence will depend upon local
conditions, upon whether the nursery is permanent or temporary and how much
expenditure can be justified on the fence.

2.1.2 Nursery Infrastructure

The essential infrastructure elements of a nursery are a water source, nursery beds,
water conveyance channels or hydrants and working tools (Fig. 2.1 ). However, a
permanent nursery should also have other infrastructure elements, such as one or
more ground-level water reservoir (GLR) or overhead water reservoir (OHR), a seed
store, staff quarters, and irrigation sprinklers. Choice of infrastructure is largely a
question of availability of funds and the size and importance of the nursery.
Discharge and quality of water are the two parameters that decide suitability of a
water source. Quality has already been discussed earlier. Discharge of water required
in a nursery will depend upon the plant production capacity of the nursery and the
method of irrigation adopted. On an average 25,000 l of water is required daily for