Subtopic: Leaching requirement and salinity control
Question Statement:
An agricultural crop is irrigated with water having an electrical conductivity of $EC_{iw} = 1.80\text{ dS/m}$. The soil salinity threshold for maintaining $100\%$ crop yield potential is $EC_e = 3.00\text{ dS/m}$. Using Rhoades' formula for leaching requirement under conventional surface irrigation:
$LR = \frac{EC_{iw}}{5 EC_e - EC_{iw}}$
the required leaching requirement fraction $LR$ expressed as a percentage ($\text{\%}$) is ________ (round off to one decimal place).