Taking into account water resources and their importance for human life and economic development, it is clear that accurate and precise determination of irrigation requirements in modern agricultural practice becomes imperative, especially in the context of increasingly pronounced climate changes and more frequent droughts. Today, there are numerous ways to measure and assess the state of soil moisture and, accordingly, the need for irrigation of individual agricultural crops, in modern agricultural science, software models used for these purposes are increasingly important. This paper provides an overview of some of the more important software models used to determine irrigation needs. Four different models (CROPWAT, EXCEL-IRR, AquaCrop and SIMDualKc) are described and configured to correspond to the state of a maize crop grown during 2021, at the Experimental Field of the Faculty of Agriculture and Food Sciences, University of Sarajevo, in Butmir. The mentioned configurations included the definition of meteorological, pedological and agronomic or biological parameters in the field and the use of software models to estimate irrigation requirements. The modeling results were presented through crop evapotranspiration, soil water depletion dynamics and crop irrigation requirements. Evaluation of the results of the generated data proves the appropriate accuracy and applicability of all models. However, each of the four used models has certain advantages and disadvantages, and practical application depends on the type of user and available data. Farmers will prefer to use simpler models such as CROPWAT and EXCEL-IRR, while researchers will prefer more complex and accurate models such as SIMDualKc and AquaCrop. 

A two-year experiment was conducted with a local maize hybrid under full (F) and deficit (D) drip irrigation and rainfed conditions (R) to estimate maize evapotranspiration in Bosnia and Herzegovina (BiH). Three approaches, namely, A&P, SIMDualKc (SD), and vegetation index (VI), to estimate the actual crop coefficient (Kc act), the actual basal crop coefficient (Kcb act), and the actual crop evapotranspiration (ETc act), were applied with the dual crop coefficient method and remote sensing (RS) data for the first time. While Kcb act from all approaches matched FAO56 tabulated values, SD showed differences in comparison to A&P of up to 0.24 in D and R conditions, especially in the initial and mid-season stages. VI demonstrated very good performance in all treatments. In F, the obtained Kc act for all approaches during the initial and end stages were higher than the tabulated values, ranging from 0.71 to 0.87 for the Kc ini act and from 0.80 to 1.06 for the Kc end act, while the mid-season period showed very good agreement with the literature. The maize crop evapotranspiration range is 769–813 mm, 480–752 mm, and 332–618 mm for F, D, and R, respectively. The results confirmed the suitability of both approaches (SD and VI) to estimate maize crop evapotranspiration under F, with the VI approach demonstrating an advantage in calculating Kcb act, Kc act, and ETc act values under water stress conditions. The higher observed yields (67.6%) under irrigation conditions emphasize the need to transition from rainfed to irrigation-dependent agriculture in BiH, even for drought-resistant crops like maize.

Aim of study: A two-year experiment (2021-2022) was conducted to assess the response of a local maize hybrid BL-43 to different water regimes (full irrigation, deficit irrigation and rainfed) at two distinguished pedo-climatic locations (Aleksandrovac and Butmir) in Bosnia and Herzegovina (BiH). Area of study: The field experiment was located in Aleksandrovac (near Banja Luka) and Butmir (near Sarajevo) in BiH. Material and methods: A randomized block design was adopted at both experimental locations with three replicates. An Excel-based irrigation tool was used to manage crop water requirements and irrigation scheduling. Main results: Crop response to water was affected by site-specific agronomic management, the duration of phenological stages and their interconnection with precipitation events. At both locations, the effect of the water inputs on grain yield was statistically significant confirming the beneficial impact of irrigation. The effect of water stress on yield was particularly pronounced at Aleksandrovac, which was under water and temperature stresses during flowering time. During both seasons and for all water regimes, the total average grain yield was greater at Butmir than at Aleksandrovac for 38% and 27%, respectively. Research highlights: This is the first experimental study conducted in BiH on the effect of irrigation on maize grain production under different pedoclimatic conditions. The study emphasizes the need for knowledge regarding the impacts that climate change is having on the productivity of one of the region's most important crops.