Impact of Climate Uncertainties, Soil Characteristics and Irrigation Scheduling on Evapotranspiration and Deep Percolation under Maize in Thrace Plane
2009
Popova, Z. (N. Pushkarov Institute of Soil Science, Sofia (Bulgaria))
The objective of this study is to assess the impact of climate uncertainties and irrigation scheduling on evapotranspiration ETa, nonused precipitation and deep percolation under maize in a vertisol Total available water TAW = 173 mm m-1 and a Chromic Cambisol TAW = 136 mm m-1, Stara Zagora region. Simulations were performed by water balance irrigation-scheduling ISAREG model that in former studies has been validated and used to generate five irrigation scheduling alternatives in agreement with past studies to develop improved irrigation practices. Simulations under present climate 1970-1992 and rainfed alternative show that: 1 ETa-dry ranges from 285 mm in the years of extreme irrigation demands probability of net irrigation requirements PI = 97% to 500 mm in the wet seasons PI = 6%) in Vertisol; 2 When results relative to both soils are compared, ETa-dry is up to 80-100 mm smaller in Chromic Cambisol over average and dry seasons PI 60%. Evapotranspiration under full irrigation ETa-max is much more stable over the studied period. It is about 560-580 mm in the dry and average years PI 60% and about 15-30 mm less in wet seasons. Nonused precipitation V-IX relative to developed irrigation scheduling alternatives and rainfed alternative is within the limits 0-100 mm over most 70-90% of the seasons. It increases to 180-250 mm in one of 75 years Pv
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