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Estimation of evapotranspiration for paddy under alternate wetting and drying irrigation practice *
Author(s) -
Shekhar Shashank,
Tamilarasan R.,
Mailapalli Damodhara Rao,
Raghuwanshi Narendra Singh
Publication year - 2021
Publication title -
irrigation and drainage
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.421
H-Index - 38
eISSN - 1531-0361
pISSN - 1531-0353
DOI - 10.1002/ird.2536
Subject(s) - lysimeter , evapotranspiration , crop coefficient , irrigation , mathematics , environmental science , hydrology (agriculture) , agronomy , soil science , soil water , engineering , ecology , geotechnical engineering , biology
Crop evapotranspiration ( ET C ) of rice under an alternate wetting and drying (AWD) irrigation practice may be different from conventional (CON) irrigation methods due to the drying (water stress) phase. The focus of this study was to identify a suitable approach for estimating ET C for a rice crop under AWD practice. Field lysimeters were used for estimating daily ET C under AWD and CON practices during monsoon and non‐monsoon seasons. Lysimeter‐based evapotranspiration ( ET C_Lys ) was compared with that resulting from the product of reference evapotranspiration (FAO‐56 Penman–Monteith equation), crop coefficient (FAO tabulated values‐ K C_Tab and FAO equation‐ K C_Eqn ) and soil water stress coefficient (linear equation‐ K S_Lin ; FAO equation‐ K S_FAO ; logarithmic equation‐ K S_Log ). The K C_Eqn and K S_FAO methods were found to be better estimates for K C and K S , respectively, for AWD practice. The mean K C in initial, mid and late season for AWD were found to be very close to CON practice. The K S was observed to vary from 1 to 0.15 for AWD. Overall, AWD irrigation practice saved 10–20% irrigation water with about 2% reduction in grain yield and 13% reduction in ET C . The reduction in ET C indicated that K S must be considered when calculating the ET C in rice under AWD irrigation practice.