Question

Estimate the leaching requirement when electrical conductivity (EC) value of a saturated extract of soil is 10 m mho/cm at 25% reduction in the yield of the crop. The EC of irrigation water is 1.5 m mho/cm.

(a) 15%

(b) 6.66%

(c) 7.5%

(d) 10%

This question was addressed to me by my school principal while I was bunking the class.

My question comes from Reclamation of Saline and Alkaline Lands topic in portion Water Logged Reclamation and Saline Soils for Agricultural Purposes of Irrigation Engineering

Answer 1

Right answer is (c) 7.5%

Easiest explanation: The given values are:

E.C value of saturated soil = 10 milli-mhos/cm and E.C value of irrigation water = 1.2 milli-mhos/cm.

The EC of leaching water is assumed to be twice the EC value of saturation soil extract i.e. = 2 x 10 = 20 milli-mhos/cm

L.R = EC of irrigation water / EC of leaching water = 1.5 / 20 x 100%

L.R = 7.5%.