A soil stratum $40 c m$ deep with field capacity, wilting point and dry density $25 %$ , $10 %$ and $1.5 g m / c m^{3}$ respectively is grown with a crop having consumptive use requirement of $0.6 m m / d a y$ . If the soil is initially at field capacity , the number of days after which irrigation is required will be _____.
150

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Solution

The correct option is A 150
Given, F.C. = 25% = 0.25

W.P. = 10% = 0.10

$γ_{w} = 1.5 g m / c m^{3}$

Moisture holding capacity of stratum,
$= \frac{γ_{d} \times d}{γ_{w}} (FC - WP)$

$= \frac{1.5 \times 40}{1} (0.25 - 0.10) = 9 c m = 90 m m$

$Irrigation interval = \frac{Moisture holding capacity}{Consumptive use}$

$= \frac{90}{0.6}$

$= 150 d a y s$

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The correct option is A 150Given, F.C. = 25% = 0.25 W.P. = 10% = 0.10 γw=1.5 gm/cm3 Moisture holding capacity of stratum, =γd×dγw(FC - WP) =1.5×401(0.25−0.10)=9 cm=90 mm Irrigation interval=Moisture holding capacityConsumptive use =900.6 =150 days