IRRIGATION SCHEDULING STUDY UNDER CHANGING CLIMATE IN PLOVDIV REGION | ИЗСЛЕДВАНИЯ ВЪРХУ ПОЛИВНИТЕ РЕЖИМИ ПРИ ПРОМЕНЯЩИЯ СЕ КЛИМАТ В РАЙОНА НА ПЛОВДИВ
2014
Popova, Z., N. Pushkarov Institute of Soil Science, Sofia (Bulgaria) | Ivanova, M., N. Pushkarov Institute of Soil Science, Sofia (Bulgaria) | Doneva, K., N. Pushkarov Institute of Soil Science, Sofia (Bulgaria)
Plovdiv agricultural region, Thracian Lowland, proved to be a most vulnerable to drought in this country. Detected climate change there creates uncertainties for irrigation scheduling. To cope with them simulations were performed for past 1952-1984 and present 1970-2004 weather conditions using the calibrated irrigation scheduling simulation WinISAREG model for two maize varieties, the semi-early hybrid Pioneer P37-37 and the late hybrid H708, grown on alluvial soil Total Available Water=116 mm m-1. All are subjects of this study, which compares four irrigation scheduling alternatives: 1 refilling the soil reservoir and adopting a management-allowed depletion fraction MAD of 0.60; 2 refilling the soil reservoir and adopting MAD=0.45; 3 partially refilling the soil reservoir and adopting MAD=0.60, and 4 crop without irrigation. Analyses using simulations relative to every year during 1952-1984 show that alternative 2 leads to less impact on yields but irrigation demands are larger when compared to alternatives 1 and 3, allowing a larger water depletion with MAD=0.60. Alternative 3 that partially refills the soil reservoir leads to best storage of precipitation and requires up to 50 mm less irrigation water than alternative 2 over the whole range of seasons. It is found that for the average irrigation demand year of present climate 1974 adaptation to drought consists only of irrigation timing adjustment that leads to last irrigation date after 15/08. For the very dry year 2000 of the same period all alternative irrigation schedules behave similarly requiring additional irrigation/s compared to the very dry year of the past weather conditions 1970.
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