A 10 ha field has 1.2 m deep layer of sandy loam soil underlain by sandy soil up to a depth of 5 m. A pre-irrigation rainfall brings moisture content of the top 0.3 m layer to its field capacity. The moisture content of rest of the sandy loam layer remains at permanent wilting point. FC and PWP are 32% and 16% respectively for the sandy loam soil. The field is irrigated with a stream size of 240 L s⁻¹ for 24 hours. Considering the drainage from the sandy loam soil as deep percolation, application efficiency and deep percolation ratio in percent respectively are
Options:
(A) 56.40 and 43.60
(B) 69.44 and 30.56
(C) 75.18 and 24.82
(D) 92.60 and 7.40
Official Answer Key:
B
Step-by-Step Solution & Explanation
Volume of water applied = 240 L/s × 24×3600 s = 20,736,000 L = 20,736 m³.
Water USEFULLY stored (raising the remaining 1.2−0.3=0.9 m sandy-loam layer, currently at PWP, up to FC) = (FC−PWP)×0.9m×Area = (0.32−0.16)×0.9×(10×10⁴ m²) = 0.144×100,000 = 14,400 m³.
Application efficiency = useful storage/applied = 14,400/20,736 × 100 = 69.44%.
Deep percolation ratio = 100−69.44 = 30.56%. Answer: (B).
Section 6 — Agricultural Process Engineering
Practice This in Real CBT Exam Interface
Test yourself with the official TCS-iON palette, virtual calculator, and immediate performance analytics.