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NIR and FIR and frequency of Irrigation

Following particulars were recorded from agriculture Land growing where:-

• FC = 20%
• PWP = 8%
• Permissible Depletion of available moisture = 50%
• Root Zone Depth = 2m
• Dry unit weight of soil =1400 kg/m^3
• Effective Rain fall = 20mm.
• Cu = 5.6mm/d
• Find NIR and FIR if application losses are 10%. Also,Find the Frequency of Irrigation.
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$$As, N I R=C I R+\underbrace{L R+P S R}_{0}$$ Assuming leaching Requirement and Pre-sowing Requirement to be Zero, $$\text { NIR }=C I R=C u-\text { Peff }$$

• Depth Required to the raised to satisfy consumptive use $=1.4 \times 2 \mathrm{~m}× 0.06$ $=0.168 \mathrm{~m}$
• [Out of total Required of $.168 \mathrm{~m}$ for the crop, $20 \mathrm{~mm}$ is contributed by Rainfall]

$\therefore$ NIR $=168-20=148 \mathrm{~mm}$

• $\quad F I R=\frac{N I R}{N a}=\frac{148}{0.9}=164.44 \mathrm{~mm}$

• $f=\frac{\text { Total Depth ofwater a vailablefiom }}{\text { various sources }}$

$$f=\frac{168 d}{5.6}=30 \text { Days }$$