Climatic and soil characteristics and crop parameters of optimized agro-climatic regions for maize

Zornitsa Popova, Maria Ivanova, Emil Dimitrov, Ivan Varlev

Abstract: The objectives of the study are to discuss and provide appropriate climatic and soil characteristics and crop parameters for decision making on maize irrigation relative to five agro-climatic regions in the form of: a) quantiles of inter-annual and interregional variability of precipitation and ET0; b) Bulgarian maps with average precipitation and average reference evapotranspiration ET0; c) Bulgarian soil classes in terms of texture, field capacity, wilting point and total available soil water (mm m-1); d)validated crop ET modelling parameters, as limiting dates of local maize development stages, appropriate crop coefficients Kc and soil water depletion fractions for no stress p. Finally, the conventional maize irrigation depths are compared with that simulated through the validated soil water balance (SWB) WinISAREG model application to identified agro-climatic regions. Considered ET0 and precipitation are the main climate variables that influence crop water requirements for irrigation. However, irrigation requirements are also influenced by soil characteristics, mainly FC, WP and TAW, and crop parameters, as rooting zone depth, validated Kc - coefficients and p – fractions relative to the crop development stages and respective limiting dates. All these parameters are also required input for SWB and irrigation scheduling WinISAREG, PILOTE and others model application. Map of Bulgarian soils and results of previous studies support identification of soil classes of small, average and large water holding capacity for each agro-climatic regions.

Keywords: maize irrigation requirements, SWB WinISAREG model, precipitation, reference evapotranspiration PMET0, soil classes, agro-climatic regions identification, spatial distribution maps

Date published: 2021-02-17