In this studies, a plant water needs index was defined as an amount of rainfall, in the period of plant increasing water demands, which didn't increase a yield of an irrigated plants. Such defined optimal rainfall was calculated on the basis of results of long-term field experiments carried out on two kinds of soil in a region of Bydgoszcz. Irrigation needs understood as rainfall insufficiency in the period of plant increasing water demands, were calculated as a difference be-tween optimal and actual rainfall. Homogeneous rainfall data from years 1971-2005 in Mochełek (placed near Bydgoszcz) were used. Calculations of irrigation needs were made in the period of increasing water demands of the followed plants: spring cereals, medium-early potato and maize cultivated for grain. All of them were grown on two kinds of soil: a very light soil of permeable subsoil and a light soil of compact subsoil. Obtained results enabled to classify the evaluated irrigation needs. The criterions were: a number of essential individual water doses and a quantity of forecasted productive effects of the irrigated plants. Re-sults of the studies show that the irrigation needs calculated on a very light soil in the region of Bydgoszcz occurred in 87,7-97,1% (it ...
The work was carried out in order to determine the frequency of droughts in the period of increased water needs of spring cereals. In addition, based on the time variation of the standardized precipitation index SPI assessed the needs and the expected production results of the plants irrigated in the Kujawsko-Pomorskie region. Data consisted of the results of standard measurements of rainfall from 1 May to 30 June in the period 1981-2010. Rainfall data were obtained from the branches COBORU in Chrząstowo, Głębokie and Głodowo and also from the Research Station of University and Technology and Life Science in Mochełek. Based on the results of the study, it was found that, during the period of high demand for water of spring cereals, the frequency of drought conditions in the region accounted of 23,3-30,0%, depending on the locality. Extreme droughts occurred in years 2000 and 2008, strong in 1983, moderate in 1989 and weak in 1992, 2003 and 2006. Among the analyzed 30 years, in 4 years were identified very high- and high-level requirements of irrigation in spring cereals corresponding to periods of extreme, strong and moderate droughts (SPI ≤ -1.0). The expected increase in grain yield of spring cereals ...
The yield of the spring cereals depends mainly on the distribution of at-mospheric precipitation in the growing season according totheir requirements in particular growing stages. Both precipitation excess and deficiency are not de-sirable. The analysis of spring cereals' water requirements fulfillment was made on the basis of IMGW data concerning the sums of atmospheric precipitation in Siedlce in the years 1968-1997. Monthly sums of precipitation were compared with optimum values of precipitation, estimated by Klatt (Water needs..., 1989),for specific spring cerealsin particular vegetation months. The characteristics of water requirements fulfillment for particular cereals was made on the basis of differences between the values of monthly sums of precipitation during the years analyzed and the values considered as optimum. In the months of April, May and June the frequency of precipitation deficiencies was higher than the frequency of precipitation excesses for all the cereals analyzed. However, in July precipitation excesses have been registered more frequently than the deficiencies. During the analyzed thirty years, the highest values of the average precipitation deficiencies for all the spring cereals were registered in May, while the values of precipitation excesses - in July. Meteorological growing season during the analyzed years began on 30th March and ...
