Izvorni znanstveni članak
Irrigation requirements and potentials of agricultural crops in northern Croatia
Ivan Šimunić
Ankica Senta
Franjo Tomić
Sažetak
With only 11,700 ha of irrigated agricultural areas, the Republic of Croatia holds one of the last positions in Europe. Frequent droughts in recent years influenced the public opinion regarding irrigation demands. For this reason, the Government started the «National project of irrigation and management of agricultural land and waters», which will be implemented in three stages. This study was included into a part of the said project. The aims of the study were to determine crop evapotranspiration (required amount of water), soil water deficit and quality of irrigation water for two time periods (1961-2003 and 1994-2003).
Climatic data of the meteorological station Đurđevac for the period 1961-2003 were used, except for insolation data, which were taken from the meteorological station Osijek. Reference evapotranspiration (ETo) was calculated by the Penman-Monteith method, effective precipitation by the USBR method, while crop evapotranspiration (ETc) was calculated from the relation of ETo and the crop coefficient (cc), taking account of different stages of crop development. Soil water balance (water deficit) for each crop was calculated using the Palmer method (corrected and calibrated according to Vidaček, 1981) for two depth (till 0.1 m and 0.1 m-1.0 m). The studied soil had the following characteristics: silty clay-loam texture, field water capacity (Fwc)=360 mm and wilting point (Wp)=160 mm.
The following crops were studied: tobacco, soybean, sunflower, sugar beet, cabbage kale, pepper, cucumber and tomato. Data were processed with the aid of the «Cropwat» computer program.
Quality of irrigation water for the County Canal watercourse was assessed; water samples were taken at the water gauge station Kapinci in the period from 1983 to 2003. Water quality score was calculated for each year pursuant to the Water Classification Directive. The following individual watercourse quality indicators were analyzed: oxygen concentration, oxygen saturation, COD and BOD5. Of nutritious substances ammonium and nitrites were analyzed, while among microbiological indicators quality score was based on total coliform bacteria and the number of aerobic bacteria, as well as on the Pantle-Buck saporbic index.
The results show increased water requirements (evapotranspiration) of all crops in the last investigation period (1994 to 2003) compared to the period from 1961 to 2003. Average increase in water requirement of all monitored crops was 22 mm. Increased soil water deficit was also recorded, amounting on average to 8.9 mm. Water quality in the County Canal watercourse was monitored for 21 years, in 11 years of which it exceeded the third quality class according to group indicators.
The results allow the conclusion that climatic changes in the last investigation period caused increased water requirements of the crops grown, and thereby also higher water deficit in soil and the demand for providing larger quantities of suitable irrigation water.
Ključne riječi
climatic changes; irrigation requirement; water quality and classification; oxygen regimen; nutritious substances; microbiological indicators
Hrčak ID:
3619
URI
Datum izdavanja:
10.3.2006.
Posjeta: 4.026 *