1. By what number should the value from the phytometer method be multiplied when it comes to obtain possible field results?
a) 5
b) 6
c) 9
d) A Constant Number
Explanation: Since the phytometer method is tested in lab in artificial conditions, the obtained result is only relevant to the lab due different soil conditions in the open field. So, therefore in order to get or obtain exact field results we need to multiply the value of transpiration loss obtained from the method with a constant number.
2. Which type of soil has less ratio of AET/PET than the other?
a) Clayey Soil
b) Sandy Soil
c) Alluvial Soil
d) Black Soil
Explanation: The ratio AET/PET is directly proportional to available moisture. Sandy soil has less availability of moisture than the other type of soils like clayey soil, alluvial soil, and black soil. So, this gives that sandy soil has less AET/PET ratio.
3. On what factors Potential Evapotranspiration critically depends?
a) Climatological Factors
b) Types of Crop
c) Types of Soils
d) Vegetation
Explanation: Potential Evapotranspiration (PET) involves transpiration process. As this process consists of transpiration losses through leaves of plant, and evaporation losses from surroundings of the plant and this directly dependent on availability of moisture which when is sufficiently available to meet the needs of the vegetation then it is called PET. Therefore this clearly states PET critically depends on climatological conditions.
4. On what factors Actual Evapotranspiration depends?
a) Climatological Factors
b) Types of Crop
c) Types of Soils
d) Characteristics of Soil and Vegetation
Explanation: Actual Evapotranspiration (AET) is actual and real evapotranspiration that occurs in any specific situation of the field. The specific situation of the field directly depends on the characteristics of soil and the type of vegetation present in that particular soil. So, therefore AET indirectly depends on the characteristics of soil and vegetation, in the field.
5. Which type of method is adopted for research studies on crops?
a) Phytometer Method
b) Lysimeter Method
c) Furrow Irrigation Method
d) Drip Irrigation Method
Explanation: Actually lysimeter method is used to determine the AET. This method consists of a tight tanker filled with a block of soil and is installed in a field of growing plants. The conditions to maintain this tanker on par with conditions of the field and the measurement of water added to the tanker to maintain moisture content are time-consuming and costlier field studies.
6. Which formula is extensively used for estimating seasonal water requirements?
a) Blaney-Criddle formula
b) Hargreaves pan evaporation method
c) Penman’s equation
d) Christiansen formula
Explanation: This formula is also used for estimating monthly consumptive use.
Blaney-Criddle formula is written as Cu = k.f where, f = p/40[1.8t + 32].
Where Cu = monthly/seasonal consumptive use, k = crop factor, p = monthly % of annual daylight hours in that period, and t = mean monthly temperature
7. Which method is time-consuming and expensive?
a) Tanks and Lysimeter
b) Vapour transfer method
c) Field plot method
d) Integration method
Explanation: In the Lysimeter method, the plants are grown in the tank with a sand layer at the bottom and a pan for collecting the surplus water. The consumptive use is measured by the amount of water required for the satisfactory growth of plants within tanks. Other methods are more reliable than this method.
8. Which of the following is not an empirical method of determining consumptive use?
a) Lowry Johnson method
b) Penman’s equation
c) Hargreaves method
d) Inflow-outflow method
Explanation: Inflow-outflow method is a direct method in which field observations are made and physical models are used for the purpose. Lowry Johnson, Penman, and Hargreaves method are all empirical methods.
9. The evapotranspiration rate is higher in light green vegetation than in dark green vegetation.
a) True
b) False
Explanation: The production of the rate of absorption of solar energy is high in dark green vegetation hence; its evapotranspiration rate will be higher than that of light green vegetation. The plant diseases causing yellowing of the leaves of the plants greatly reduce evapotranspiration.
10. The monthly consumptive use values for paddy are 26.69, 8.76, 14.38, 22.73, 21.29, 25.50 and 15.06 for the duration of month from June to July. What is the average daily consumptive use?
a) 7.0 mm
b) 8.0 mm
c) 7.5 mm
d) 8.5 mm
Explanation: The total consumptive use for paddy = 29.69 + 8.76 + 14.38 + 22.73 + 21.29 + 25.50 + 15.06 = 137.41 cm
Average daily consumptive use = 137.41 / period of growth in days
= 137.41 / (30+31+31+30+31+30) = 7.5 mm.