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The moisture holding capacity of the soil in a 100-hectare farm is 20 cm/m. The root zone depth of the crop is 1.0 m and peak rate to moisture use is 5 mm/day. The field is to be irrigated when 40% of the available moisture in the root zone is depleted. Calculate the frequency of irrigation.

The moisture holding capacity of the soil in a 100-hectare farm is 20 cm/m. The root zone depth of the crop is 1.0 m and peak rate to moisture use is 5 mm/day. The field is to be irrigated when 40% of the available moisture in the root zone is depleted. Calculate the frequency of irrigation. Correct Answer 16 days

The moisture holding capacity is 20 cm/m and the root zone depth = 1 m Moisture holding capacity of soil for crop = 20 x 1 = 20 cm Allowable depletion of moisture = 40% of 20 cm = 8 cm Consumptive use of water= 5 mm/day = 0.5 cm/day The frequency of irrigation = 8 / 0.5 = 16 days.

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