The instrument used for estimating consumptive use of water is

Correct option is C

The correct answer is (C) Lysimeter

Explanation:
• Consumptive use of water (also known as Evapotranspiration or ET) is the sum of water lost through evaporation from the soil surface and transpiration from plant tissues.
• A Lysimeter is a specialized instrument consisting of a large tank or container filled with soil and buried in the field such that its top is flush with the ground.
• It measures the water balance of the soil-plant system. By monitoring the amount of water added (precipitation/irrigation) and the amount of water lost through drainage, the amount lost to evapotranspiration can be calculated accurately.
• Weighing lysimeters are the most accurate as they measure the change in weight of the entire soil block over time.

Information Booster:
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• There are several types: weighing, non-weighing (drainage type), and tension lysimeters.
• ET can also be estimated indirectly using empirical formulas like Penman-Monteith or Blaney-Criddle.

Additional Knowledge:
• Anemometer (Option A): Used to measure wind speed.
• Piezometer (Option B): Used to measure the pressure or depth of groundwater (hydrostatic pressure).
• Hydrometer (Option D): Used to measure the specific gravity (density) of liquids, or in soil science, to determine soil texture by measuring the density of a suspension.