COMPARISON OF RAINFED MAIZE YIELD AND IRRIGATION REQUIREMENTS IN BULGARIA | СРАВНЯВАНЕ НА ЗАГУБИТЕ НА ДОБИВ ОТ НЕПОЛИВНА ЦАРЕВИЦА И НАПОИТЕЛНИТЕ НОРМИ В БЪЛГАРИЯ
2012
Popova, Z., Institute of Soil Science ' N. Pushkarov', Sofia (Bulgaria) | Ivanova, M., Institute of Soil Science ' N. Pushkarov', Sofia (Bulgaria)
This study compares relative yield decrease RYD of rainfed maize and net irrigation requirements NIRs for representative climate regions and soil groups in Bulgaria using the WINISAREG model for the period 1951-2004. The model was previously validated for maize hybrids of different sensitivity to water stress on soils of small, medium and large total available water TAW. Simulations are performed for Plovdiv, Stara Zagora, Sofia, Sandanski, Pleven, Lom, Silistra and Varna. RYDs are the largest in Sandanski. If TAW is medium 136-157mm m-1 there, RYD ranges from 65 to 85 % over the average years heaving probability 40PRYD75%. Yield losses are also high in Plovdiv ranging from 60 to 70% respectively. Results indicate that RYDs are the lowest in Sofia and Pleven 30RYD50%. RYD increase to over 80 % in Plovdiv and surpass 60% in Sofia in dry years PRYD25%. During the wet years PRYD85% RYD is less than 20% for the main agricultural regions in this country, except for the Black Sea Varna and the Transitional Mediterranean Sandanski climate zones. If TAW=136 mm m-1 maize irrigation requirements NIRs range from 270 and 300 mm in Sandanski for the average demand years 40PNIR75%. NIRs range between 200 and 270mm in the region of Plovdiv respectively. They are the lowest in Silistra and Sofia field 120-180mm. NIRs reach 480 mm in Sandanski, 430 mm in Plovdiv and 350 mm in Silistra, Pleven and Varna in the very dry years PNIRs5%. NIRs are below 100mm practically for all agricultural regions in wet years PRYD85%, except for Varna and Sandanski.
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