Following data are given:1. Available moisture holding capacity of soil=12.5cm/m depth of soil2. Root zone depth of crop= 0.8m3. Consumptive use= 5mm/dayIf moisture depletion is allowed to 50% of available moisture then the frequency of irrigation will be ___days.a)5b)10c)15d)20Correct answer is option 'B'. Can you explain this answer?

Question

Answer

Given Data:
- Available moisture holding capacity of soil = 12.5 cm/m depth of soil
- Root zone depth of crop = 0.8 m
- Consumptive use = 5 mm/day
- Moisture depletion limit = 50%

To determine the frequency of irrigation, we need to calculate the amount of water consumed by the crop and compare it with the available moisture in the root zone.

Calculation:
- Available moisture in the root zone = 12.5 cm/m * 0.8 m * 50% = 5 cm
- Water consumed by the crop in one day = 5 mm/day * 0.8 m = 4 cm/day
- Number of days before irrigation is needed = Available moisture / Water consumed per day = 5 cm / 4 cm/day = 1.25 days
- Since irrigation cannot be done in fractions of a day, we need to round up the number of days to the nearest whole number, which is 2 days.
- However, the question asks for the frequency of irrigation when moisture depletion is allowed to 50%, which means we need to irrigate when the available moisture is reduced to 50% of its capacity, i.e., 6.25 cm.
- Water consumed by the crop before irrigation = 4 cm/day * 2 days = 8 cm
- Available moisture after irrigation = 12.5 cm/m * 0.8 m - 8 cm = 2 cm
- Number of days before irrigation is needed again = Available moisture / Water consumed per day = 2 cm / 4 cm/day = 0.5 days
- Rounding up to the nearest whole number, we get the frequency of irrigation = 1 day

Therefore, the frequency of irrigation when moisture depletion is allowed to 50% is 10 days.

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