Estimation of reference evapotranspiration (Eto) by different methods and determination of crop water requirement of major kharif
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Date
2018-08-23
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Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani
Abstract
The research work was conducted for “Estimation of Reference evapotranspiration (ETo) by different methods and determination of crop water requirement of major kharif cereals” during 2017-18. The historical daily weather data (29 to 35 years) for all districts except Hingoli were obtained from IMD, Pune. Daily mean data of all parameters were used to calculate reference evapotranspiration (ETo) by eleven methods for Parbhani district and by two methods for Aurangabad, Jalna, Parbhani, Nanded, Osmanabad, Latur and Beed districts. The daily crop water requirement (ETc) of major kharif cereals (Sorghum, Maize and Pearlmillet) was determined by multiplying daily ETo of each districts with FAO-56 Kc values.
The results indicated that, for Parbhani district highest daily ETo is 13.17 mm
day-1 Hargreaves-Samani method (H-S method) and lowest is 3.93 mm day-1 (Turc method). Highest weekly ETo is 13.17 mm day-1 (H-S method) and lowest is 3.27 mm day-1 (Modified Penman method). Highest monthly ETo is 401.76 mm (H-S method) and lowest is 107.07 mm (Modified Penman method). During summer season ETo was found to vary between FAO Modified Penman method (522.76 mm) to H-S method (1985.13 mm) while during kharif season it varied between Turc method (370.57 mm) to H-S method (1530.56 mm) and in rabi season it was between Modified Penman method (369.66 mm) to H-S method (1305.39 mm). Highest annual ETo is 4821.09 mm (H-S method) and lowest is 1284.86 mm (Modified Penman method).
The result shows that, Hargreaves and Hargreaves-Samani (H-S) method across the seven districts of Marathwada region revealed that the highest daily, weekly, monthly, seasonal and annual ETo is observed at Parbhani and lowest at Aurangabad.
The amount of water requirement (ETc) for kharif cereals was found to increase with the passage of time. The maximum amount of water is required at the crop development and midseason stages and comparatively less water is required in initial and maturity stages. The result indicated that, for Parbhani district highest ETc of kharif sorghum is by H-S method (1061.07 mm) while lowest by Turc method (259.84 mm), highest ETc of kharif maize is by H-S method (908.93 mm) while lowest by Turc method (209.43 mm) and highest ETc of kharif pearlmillet is by H-S method (710.48 mm) while lowest by Turc method (155.91 mm).
The result from Hargreaves method across the seven districts of Marathwada region revealed that, the highest ETc of kharif sorghum in Parbhani (436.04 mm) while lowest in Aurangabad (399.42 mm), highest ETc of kharif maize in Parbhani (373.13 mm) while lowest in Aurangabad (340.74 mm) and highest ETc of kharif pearlmillet in Parbhani (291.69 mm) while lowest in Aurangabad (265.02 mm).
The result from Hargreaves-Samani (H-S) method across the seven districts of Marathwada region revealed that, highest ETc of kharif sorghum in Parbhani (436.04 mm) while lowest in Aurangabad (978.57 mm), highest ETc of kharif maize in Parbhani (914.16 mm) while lowest in Aurangabad (834.82 mm), highest ETc of kharif pearlmillet in Parbhani (714.64 mm) while lowest in Aurangabad (649.30 mm).
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