CLIMATE CHANGE IMPACT ON IRRIGATION NEED OF FIELD CROPS ON DANUBIAN LOWLAND

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1 Takáč, J., Šiška, B., Nováková, M.: Cliate Change Ipact on Irrigation Need of Field Crops on Danubian Lowland Scientific Conference, 6th 9th Septeber, Topoľčianky, Slovakia CLIMATE CHANGE IMPACT ON IRRIGATION NEED OF FIELD CROPS ON DANUBIAN LOWLAND Jozef Takáč, Bernard Šiška, Martina Nováková Soil Science and Conservation Research Institute, Gagarinova, 87 3 Bratislava, Slovakia, Dept. of Ecology, Slovak University of Agriculture, Mariánska, 94 Nitra, Slovakia Abstract. Evaluation of cliate change ipacts on soil water regie of field crops was based on siulations by agroecological odel DAISY. Irrigation needs were calculated for winter wheat, spring barley, corn aize and sugar beet. Water regies were siulated in variants: rainfed and water liited irrigation. Irrigation was applied autoatically after decreasing of soil water content below 5% of available water capacity for each of evaluated crop. Effect of gradual increase of CO concentration was taken into account for two cliate change scenarios ( A and B). Increasing of variability and decreasing of soil water content during vegetation period is expected according to the statistical analyses of siulations. According to both eission scenarios consequent increase of potential evapotranspiration and crop water requireents would gradually increase up to tie horizon 7. Increase of irrigation need by 55 % was found for field crops in cliate change conditions. CO concentration can positively influence productivity of C3 crops due to increase of water use efficiency if water is available in soil profile. On the other hand variability of yields will be influence by ore frequent drought episodes. As resulted fro the siulations of cliate change ipacts the shortage of soil water will decline. Nuber of days with available water capacity below 5% will increase during the growing season of field crops and evoke increase of irrigation needs. The irrigation season will start earlier and will persist for longer tie. Introduction Cliatic conditions becoe the ost iportant factor influencing variability of field crop yields in Slovakia today. Increase of annual ean air teperature by about C was occurred on ost of cliatic stations in Slovakia during last century. On the other hand annual precipitations decreased by about % on Danubian lowland during this period. (Lapin et al. ). Increase of air teperature and shortage of precipitations create conditions for drought occurrence especially on lowlands of Slovakia. According to outputs of General Circulation Models (GCM) this trend is also supposed for future cliate (Šiška & Takáč 8). Those facts call for analyses of drought occurrence in conditions of cliate change on territory of Slovak republic. According to natural cliate variability and the duration of drought several levels of drought can be defined (Hayes et al. 999; Hei ). Cliatic water balance was frequently analyzed in any works for evaluation of drought conditions of Central Europe (Tolain 997; Dubrovský et al., 5, Ditarová et al. 6; Trnka et al. 8; Hlásný & Baláž 8). This index was also used for agrocliatic regionalization of Slovak Republic during period of (Kurpelová et al. 975) and (Šiška & Špánik 8). According to GCM there is supposed decrease of soil water content is supposed on lowlands of Slovakia since April till October with gradation in period July - Septeber (Tolain 997). During suer season the ean soil water content will decrease below 5% of available water capacity (AWC) up to tie horizon of the year 75 on the southern part of Danubian lowland and Zahorie lowland, and below 6% on East Slovakian and Northern part of Danubian lowlands (Takáč ). Irrigation water need will significantly increase in condition of cliate change. According to analyses of eteorological data fro cliatic stations on the territory of Czechoslovakia the increase of onthly ean air teperatures by.5 C led to increase of the irrigation water deand by to 35%. The deand is doubled if the teperature rise by about 5 C (Kos 97). Winter wheat and soybean yield odeling in northern Italy (Modena) showed that to keep the present level of yields, 6 to 9 % ore irrigation water is required in condition of cliate change (Tubiello et al. ). Data and ethods Evaluation of the cliate change ipacts on soil water regie under field crops was based on siulations by agroecological odel DAISY. DAISY is a one-diensional odel siulating water, energy, nitrogen and soil organic atter balance. Crop developent and yield is possible to siulate in dependence on crop rotation and various anageent strategy. DAISY siulates plant growth and developent, including the accuulation of dry atter and nitrogen content in different plant parts. The ain plant-growth

2 Takáč, J., Šiška, B., Nováková, M.: Cliate Change Ipact on Irrigation Need of Field Crops on Danubian Lowland Scientific Conference, 6th 9th Septeber, Topoľčianky, Slovakia processes considered in DAISY are photosynthesis, respiration, partitioning of assiilates, stress factors and leaf and root developent. DAISY allows for building coplex anageent scenarios (Hansen et al. 99; Hansen ). Global radiation, air ean teperature and precipitation for xco cliate were generated by general circulation odel CCCM (Lapin et al. ). Meteorological data for reference period of years representing Danubian Lowland cae fro cliatic station Hurbanovo (47 5 N, 8 E). Crop yields were siulated for the reference period of years in variants for eission scenarios A and B. Crop paraeters were set up according to the experiental data fro field trials of Research Institute of Irrigation located in Most near Bratislava during years Confiration of the odel was based on the results fro experiental plots in Lehnice far as well as on the data fro Stationary Field Experient of Research Institute of Irrigation fro the years (Takáč & Košč 995). Rainfed and irrigated variants were evaluated. DAISY odel calculates photosynthesis rate using a light saturation response curve. The effect of CO concentration was included to the DAISY paraeterization according to light saturated photosynthesis rate F [g CO. -.h - ] and initial light use efficiency є [(g CO. -.h - )/(W. - )]. Efficiency of photo synthetically active radiation for winter wheat, and spring barley, aize and sugar beet was recalculated in dependence upon CO concentration in the atosphere (Cure & Ackock 986) for eission scenarios A and B (IPCC ). Gradual increase of CO concentration was taken into account. Based on the statistical analyses of soil hydrophysical properties (Nováková 996) ediu textured chernoze soil profile with 3.5 % huus content in topsoil was considered as representative for the Danubian Lowland. Horizons of soil profile were defined according to texture, bulk density, paraeters of retention curves, hydraulic conductivity, huus content and C/N ratio. Rooting depth was not liited by the soil. Crop rotations of six crops (spring barley, winter wheat, aize, sugar beet, alfalfa, potato) were set up. The water regie was siulated in variants: rainfed and water liited irrigation. Irrigation was applied autoatically after decreasing of soil water content below 5% of AWC for each evaluated crop. Irrigation aount 3 was siulated. Interval between irrigations was set up to days. This restriction assuption was chosen because liited irrigation water supply is expected. Results and disscussion Water balance of soil profile is significantly influenced by evapotranspiration. Reference crop evapotranspiration (ET ) in reference period of years was 89. Shortage of available water especially during growing season caused that actual evapotranspiration (ET) was only 48. ET would increase by about 7 % according to B (879 ) and by % to A (98 ). Crop specific potential evapotranspiration (ET c ) up to tie horizon 7 will increase by 5% ( B) or % ( A) as copared with reference period of years. Relatively higher increase in ET c values is supposed for suer tie crops (e.g. aize) as copared with wintering crops or crops of the spring growing season. Annual ET will increase consequently towards ore distanced tie horizons according to B only. According to A increase of ET is supposed only in near future because shortage of water in soil profile in far future will reduce evapotranspiration (Table ). Taking into account only the period fro sowing to harvest ore significant increase of ET c can be expected for the suer crops. ET will rapidly grow in the initial period and then gradually decline or stabilize (Table ). Rise of the evaporation requireents will lead to increased water scarcity in the spring and suer, despite increasing precipitation totals (Fig ). R - ET [] Scenario A - 4 A 4-7 A 7 - B - 4 B 4-7 B 7 - DJF MAM JJA SON Figure. Seasonal cliate water balance in the period and according to the cliate change Soil oisture is one of the ost variable soil properties. Soil oisture regie is seasonally influenced on lowlands of Slovakia. The axiu soil water content is recorded in dependence upon winter rains or date of snow elting at the end of winter period or at the beginning of spring and the iniu soil water content is recorded during suer onths. Median values (every second year) of SWC bellow 5 % of AWC lasted according to odel siulations since June till the

3 Takáč, J., Šiška, B., Nováková, M.: Cliate Change Ipact on Irrigation Need of Field Crops on Danubian Lowland Scientific Conference, 6th 9th Septeber, Topoľčianky, Slovakia end of Septeber. If the upper quartile (3 fro 4 years) values are considered the water content bellow 5 % of AWC is recorded since the beginning of July until the second decade of Septeber. Siulations with cliate change scenarios data increase variability of water content regie during year. Generally the decline of soil water content during growing seasons especially in suer onths (since May till Septeber) confir decreases of all evaluated statistical characters, upper and lower quartiles, edians and averages (Fig ). Siulations according to A show that the upper quartile of the water content in soil layer c will be deeply below 5 % of AWC since half of June till half of Septeber up to horizon of years 7. On the other hand in soe years the SWC below 5 % of AWC are not calculated. Table Mean annual totals of reference crop evapotranspiration ET, crop specific potential evapotranspiration ET c and actual evapotranspiration ET in the period and according to the cliate change scenarios Scenario Period ET ET c ET A B Nuber of days with SWC below 5 % of AWC will rise in conditions of cliate change (Fig 3). Continual period of days when SWC is below 5 % of AWC will rise too. The extree period of drought according to this paraeter was siulated according to A with duration since the end of May till half of Deceber. The ost frequent decrease of SWC bellow 5 % of AWC days in average is prognosed for July and August. According to A this decrease could be expected during whole July and August at later tie horizons. This trend of increasing of drought periods has been observed even during recent years. Coparing results of siulations for years and there were recorded in average four days ore with SWC below 5 % of AWC towards later period on Danubian Lowland. The sae trend was found for duration of the continual drought when increase up to days was calculated. On the other hand rising concentration of CO in the atosphere can positively influence water use efficiency (WUE) especially for C3 crops while C4 crops would not be influenced significantly (Fig 4). Table Crop specific potential evapotranspiration ET c and actual evapotranspiration fro sowing to harvest in the period and according to the cliate change scenarios Winter Spring Maize Scenario Period Wheat Barley ET c ET ET c ET ET c ET A B soil water content [] Figure Annual course of ean soil water content in the horizon c [] on Danubian Lowland in the period and according to the cliate change Table 3 Earliest (e) and ean () date of first irrigation of selected crops in the period and according to the cliate change scenarios Scena -rio A B Perio d A -4 A 4-7 A 7- B -4 B 4-7 B Spring Winter Sugar Maize barley wheat beet e e e e M

4 n 54 Takáč, J., Šiška, B., Nováková, M.: Cliate Change Ipact on Irrigation Need of Field Crops on Danubian Lowland Scientific Conference, 6th 9th Septeber, Topoľčianky, Slovakia Table 4 Mean duration of the irrigation season (days) of selected crops on Danubian Lowland in the period and according to the cliate change scenarios Scenari o A B Perio d Sprin g barley Winte r wheat Maiz e Suga r beet Rainfall totals and their distributions in growing season do not cover raising water deand of plant production even today. Irrigation plays iportant role to reach sustainable yields of field crops. Siulated irrigation requireents for different crops in reference period of years and condition of cliate change are given on fig. According to B irrigation requireents of different field crops can increase by 5 % up to evaluated horizons of cliate change and by to 55 % according to A as copared with reference period of years. The highest increase of irrigation requireents was found for sugar beet crops: 56 to5 % according to B and 5 to55 % according to A. The increase of variability on irrigation requireents in different year was found (Fig 6) B -4 A -4 Figure 3 Mean annual nuber of days with soil water content below 5 % of available water capacity in the period and according to the cliate change Siulations show that tie schedule of irrigation will also change during growing season of field crops. In dependence on crop, and tie horizon of cliate change the first irrigation should be applied in average by 7 7 days earlier then in conditions of reference cliate and by 38 days in extree years on Danubian lowland (Table 3). Duration of irrigation season will be longer (Table 4) and water will becoe the ost iportant liit of sustainable plant production. ] - g. [ k E U W ] - g. k [ E U W Trend A Trend B 966 to A B Figure Winter wheat (up) and aize (down) water use efficiency WUE [kg. - ] in 966 and according to the cliate change B Trend A Trend B 966 to A B A 4-7 B 7- A 7- winter wheat aize

5 irrigation [ Takáč, J., Šiška, 44 B., Nováková, M.: Cliate 39 Change Ipact on Irrigation Need of Field Crops on Danubian Lowland Šiška, B. Hauptvogl, M. Eliašová, 7 M. (eds.). 5 Biocliate: Source and Liit of Social Developent International Scientific Conference, 6th 9th Septeber, Topoľčianky, Slovakia B -4 A -4 B 4-7 A 4-7 B 7- A 7- easures to reduce negative cliate change ipacts on agricultural landscape of Danubian lowland Figure 5 Average irrigation requireent [] of field crops in the period and according to the cliate change scenarios Conclusions Cliate change ipacts on soil water regie and irrigation requireent under different field crops growing on Danubian Lowland were evaluated by agroecological odel DAISY. Meteorological data generated according GCM CGCM were applied according to eission scenarios A and B. Gradual increase of CO concentration in the atosphere was taken into account for evaluations. irrigation [] 3 spring barley B -4 A -4 B 4-7 A 4-7 B 7- A 7-3 winter wheat B -4 A -4 B 4-7 A 4-7 B 7- Figure Statistical characteristics of irrigation requireent [] of field crops in the period and according to the cliate change According to both eission scenarios consequent increase of potential evapotranspiration, actual evapotranspiration and crop water requireents will increase up to tie horizon fro 7 to. Rising CO concentration will positively influence productivity of C3 crops due to increase of water use efficiency. As resulted fro siulations of cliate change ipacts the shortage of soil water will deepen. Nuber of days with available water capacity below 5% will increase during the growing season of field crops and it will evoke increase of irrigation requireent. The irrigation season will start earlier and will persist for longer tie. Insufficient water sources for irrigation could be the liiting factor of sustainable yields of field crops. Acknowledgeents: We gratefully acknowledge the support of the Grant Agency of the Slovak Republic: VEGA /866/: Proposal of adaptive A aize B -4 A -4 B 4-7 A 4-7 B 7- A sugar beet B -4 A -4 B 4-7 A 4-7 B 7- A 7- References Ditarová Ľ., Keť J., Střelcová K. & Gőőry D. Effects of drought on selected physiological paraeters of young beech trees under stress conditions. Ekológia (Bratislava) 5: Dubrovský M., Trnka M., Svoboda M., Gates M., Šilháte D., Žalud Z. & Seerádová D. Drought conditions in the Czech Republic in present and changed cliate. In: Proceedings of the European Geophysical Union, Vienna Hansen S.. DAISY, a Flexible Soil Plant - Atosphere Syste Model. Equation Section. The Royal Veterinary and Agricultural University. Copenhagen, 47. Hansen S., Jensen H. E., Nielsen N. E. & Svendsen H. 99. DAISY A Soil Plant Syste Model. Danish siulation odel for transforation and transport of energy and atter in the soil-plant-atosphere syste. National Agency for Environental Protection, Copenhagen, 7 p. Hayes, M. J., Svoboda, M. D., Wilhite, D. A. & Vanyarko, O. V., 999: Monitoring the 996 Drought using the Standardized Precipitation Index. Aerican Meteorological Society 8: Hei R. R. : A review of Twentieth-Century drought indices used in the United States. Bull. Aer. Meteor. Soc. 83: 49 6 Hlásný T. & Baláž P. 8: The cliatic water balance of Slovakia based on the FAO Penan-Monteith evapotranspiration. Geografický časopis 6: 5 3. Kos Z. 97. Siulation Models of Water Supply for Irrigation in Water Resources Systes. ICID Bulletin 9: 7 5. Kurpelová M., Coufal J. & Čulík J. 97 Agrocliatic conditions of ČSSR. Príroda, Bratislava. (In Slovak) Lapin M., Melo M. & Daborská I.. Scenarios of several physically plausible cliatic eleents. MoE SR Bratislava, NCP SR : 5 3 (in Slovak) Matejka F. & Huzulák J. 99 Analysis of relationships between winter wheat leaf water potential and atospheric factors. Biologia 5: 5 Nosek M. 97. Methods in Cliatology. Acadeia, Praha, 434p. Nováková, K. 99 Hydrophysical Properties of Žitný ostrov Soils. Scientific Papers of the Research Institute of Irrigation, Bratislava, :7 (In Slovak) Šiška B. & Špánik F. 8. Agrocliatic regionalization of Slovak territory in condition of changing cliate. Meteorologický časopis : 6 6 Šiška, B. & Takáč, J. 8. Cliate Change and Agriculture of the Slovak Republic. Ipacts, Adaptive Measures and Possible Solutionns. Study of the Slovak Biocliatological Society of SAS XXIV, XXI, SBkS, Zvolen, 69 p. ISBN Škvarenina J., Tolain J., Hrvoľ J. & Škvareninová J. 8. Occurrence of Dry and Wet Periods in Altitudinal Vegetation Stages of West Carpathians in Slovakia: Tie-Series Analysis 95 In: Biocliatology and Natural Hazards (Strelcova et al. eds.), Springer-Verlag New York, LLC (in print) Takáč J.. Cliate Change Ipacts on Water Balance in Agricultural Landscape. NKP /. MoE SR, SHMI Bratislava: p. 6 6 (in Slovak) Takáč J. & Košč V. 99 Unsaturated Zone and Agriculture. Final Report. PHARE Project No. PHARE/EC/WAT/ Danubian Lowland Ground Water Model. Bratislava : MoE SR, Bratislava, 64 p.

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