COMPARISON OF METHODS FOR PLANT WATER REQUIREMENTS ON DIFFERENT SOILS

Klimatske promjene dovele su do sve češće pojave sušnih godina što ima izrazito negativan utjecaj na poljoprivrednu proizvodnju. Cilj istraživanja bio je usporediti dvije metode proračuna potreba za dodatnim navodnjavanjem te time omogućiti kvalitetnije iskorištenje vode za navodnjavanje. Istraživanje je obuhvatilo terenska i laboratorijska istraživanja na lokalitetima Tovarnik i Jagodnjak. Tlo na području Tovarnika imalo je visoki sadržaj gline, dok je tlo Jagodnjaka imalo visoki sadržaj pijeska. Nakon obavljenih pedoloških, kemijskih te analiza meteoroloških podataka svakog područja pristupilo se proračunavanju potreba biljaka za vodom i manjka vode pomoću programa HIDROKALK i CROPWAT 8.0 za prosječnu i sušnu godinu. Dobiveni proračuni su statistički obrađeni kako bi se utvrdila korelacija između korištenih metoda. Najmanji nedostatak vode na oba lokaliteta u prosječnoj i sušnoj godini koristeći program HIDROKALK imale su strne žitarice (pšenica, ječam, zob i tritikale) te uljana repica. Najveće potrebe za dodatno navodnjavanje korištenjem HIDROKALK programa imali su paprika i krastavac u sušnoj godini, Tovarnik 320,97 mm te Jagodnjak 283,86 mm. Pomoću programa CROPWAT 8.0 proračunate su najveće potrebe kod šećerne repe u sušnoj godini, na području Tovarnika 361,50 mm, a na području Jagodnjaka 311,20 mm. Najmanje potrebe proračunate su također kod strnih žitarica i uljane repice. Redukcija prinosa proračunata je pomoću programa CROPWAT 8.0 za oba lokaliteta. Strne žitarice nisu pokazale smanjenje prinosa bez obzira radi li se o prosječnoj ili sušnoj godini. Najveća redukcija prinosa proračunata je kod merkantilnog kukuruz u sušnoj godini (Tovarnik 66,2 %, Jagodnjak 57,4 %). Statističkom obradom podataka utvrđene su vrlo značajne korelacije između korištenih metoda za sve uzorke r= 0,938.Climate change has led to more frequent occurrence of drought years, which has an extremely negative impact on agricultural production. The aim of the research was to compare two methods for calculation of water demand and thus enable better utilization of water used in irrigation. The study included field and laboratory research on two sites:Tovarnik and Jagodnjak. The soil in the area of Tovarnik had high clay content, while the soils of Jagodnjak had high sand content. After the soil physical and chemical analysis and analysis of climatic conditions of each area, HIDROKALK and CROPWAT 8.0 programs were usedto calculate plant water requirements for average and dry year. The calculation results were analyzed to determine the correlation between the two methods. The lowest water demand using HIDROKALK program at both sites, in an average and in a dry year,was calculated for cereals (wheat, barley, oats and triticale) and oilseed rape. Using HIDROKALK programe highest demand for waterhad pepper and cucumber in the dry year, at Tovarnik 320,97 mm and at Jagodnjak 283,86 mm. CROPWAT 8.0 program calculated that the highest demand for water had sugar beet in the dry year, at the area of Tovarnik 361,50 mm and at the area of Jagodnjak 311,20 mm. The lowest demand was also calculated for cereals and rapeseed. The reduction of yield was calculated using CROPWAT 8.0 for both sites. Cereals showed no reduction in yield, regardless of whether was it was an average or dry year. The highest reduction in yield was calculated for mercantile maize in the dry year (Tovarnik 66,2%, Jagodnjak 57,4%). The statistical analysis of data showed highly significant correlation between the two methods used for all samples r= 0,938