ABSTRACT
Reduction in yield ƒ Generally, whichever the plant, the yield decreases more or less linearly with increase in measured electrical conductivity (Fig. 13.18).
For example, the yield of lucerne drops by 7.3 per cent per additional mmho/cm when the conductivity exceeds 2.0 mmhos/cm. For a soil with EC = 5.4, we get
Yield = 100 – 7.3(5.4 – 2.0) = 75%
The correlations are so good that tables have been drawn up for predicting the yield, plant by plant, in relation to soil salinity (Bresler et al. 1982). Decrease in yield is noticeable much before toxicity symptoms appear. In fact, sensitivity to salt depends not only on species but also on variety or cultivar and growth stage. Absorption of salts can take place directly through the leaves if sprinkler irrigation is done with saline water. In this case, scorching appears on the leaves and the tolerance threshold is no higher than 5 meq/l, sometimes lower if the water gets concentrated by evaporation. Fruits are also affected. For avoiding this, irrigation at night is desirable.
