The field experiment was conducted during the years 2006-2008 on a very light soil in central Poland in an area particularly deficient in water. The key aim of the study was the reaction of 10 European asparagus ( Asparagus officinalis L.) cultivars: Ravel, Rambo, Rally, Ramada, Rapsody, Cipres, Plaverd, Backlim, Grolim, Orane, grown for green spear production to surface drip irrigation. Drip irrigation of the asparagus plants had a positive effect both on summer stalks and green spears. A significant increase in the height, number and diameter of summer stalks, as well as an increase in the marketable yield, weight and number of green spears was observed for most of the cultivars. Both factors, the irrigation used and the asparagus cultivars, significantly modified the antioxidant content in asparagus spears. The Rapsody cultivar accumulated significantly more, and the Grolim cultivar significantly less, total polyphenols in asparagus spears at unirrigated plots. An inverse relationship was obtained in the Grolim cultivar with respect to the content of vitamin C, which accumulated the most of it under the irrigation conditions. The Ramada cultivar from irrigated plots contained significantly the highest amount of total carotenoids. In turn, the Cipres and Grolim cultivars from irrigated plots were characterized by the highest antioxidant activity.

Willows are one of the plants which can be used to produce biomass for energy purposes. Biomass production is classified as a renewable energy source. Increasing the share of renewable sources is one of the priority actions for European Union countries due to the need to reduce greenhouse gas emissions. To achieve the best possible growth of the willow and increase its biomass for fuel, it is crucial to provide optimal water conditions for its growth. The aim of the study was to determine the water requirements of willows under the conditions of the western Polish climate and to verify whether this area is potentially favourable for willow cultivation. The novelty of this paper lies in its multi-year climatic analysis in the context of willow water needs for the area of three voivodships: Lubusz, Lower Silesian, and West Pomeranian. This is one of the few willow water-needs analyses for this region which considers the potential for widespread willow cultivation and biomass production in western Poland. Reference evapotranspiration (ETo) was determined by the Blaney-Criddle equation and then, using plant coefficients, water needs for willow were determined. Calculations were carried out for the growing season lasting from 21 May to 31 October. The estimated water needs during the vegetation season amounted on average to 408 mm for the West Pomeranian Voivodeship, 405 mm for the Lubusz Voivodeship, and 402 mm for the Lower Silesian Voivodeship. The conducted analysis of variance (ANOVA) showed that these needs do not differ significantly between the voivodeships. Therefore, it can be concluded that the water requirements of willows in western Poland do not differ significantly, and the whole region shows similar water conditions for willow cultivation. Furthermore, it was found that water needs are increasing from decade to decade, making rational water management necessary. This is particularly important in countries with limited water resources, such as Poland. Correctly determining the water requirements of willow and applying them to the cultivation of this plant should increase the biomass obtained. With appropriate management, willow cultivation in Poland can provide an alternative energy source to coal.

Lakes are the most important freshwater resources for humans. It is stated that together with population growth, unplanned urbanization, excessive water consumption, industrialization, and unconscious irrigation, global climate change causes changes in the water levels and volumes of lakes. Lake Eğirdir in Turkey, which is important in terms of drinking and irrigation water use, was chosen as the study area. Lake Eğirdir water level (LWL) and water volume (LWV) values measured between 1988–2019 were used. Dependencies in the annual LWL and LWV were examined by autocorrelation analysis, and trend changes were examined by regression analysis, the Mann-Kendall rank correlation test, and the Şen innovation trend test. The research has shown a significant decrease since 2000 in LWL and since 1990 in LWV. The LWL has decreased by −1.272 to −3.514 m and the LWV has decreased by −72.980 to −1082.134 hm3 in approximately 32 years. The actions to be taken based on the values determined in this study will help protect the water resources of lakes. As a result of the tests used in our study, it was determined that there were decreases in both the water level and the volume of the lake. The climatic changes in the lake basin and the decrease in the water resources feeding the lake are shown as the biggest factor in these reductions.

The climatic changes observed in Poland are manifested by an increase in air temperature, but not an increase in rainfall, which causes an increase in the water needs of plants, and hence the necessity to develop irrigation systems for crops. The aim of this study was to assess the water needs of grapevines in 2021–2050 in the Bydgoszcz region (northern Poland), an area with high requirements for supplementary irrigation. The calculations were based on the expected changes in air temperature according to the climate change scenario for Poland: the 4th Intergovernmental Panel on Climate Change—Special Report on Emissions Scenarios: balanced scenario (A1B). The average monthly temperature in 1981–2010 was used in the calculations. The water needs of grapevines were estimated using the reference evapotranspiration calculated using the Blaney–Criddle equation, and then using the crop coefficient and potential (crop) evapotranspiration. It was found that in 2021–2050, the water needs of grapevines, both during the growing season (May–September) and during the irrigation period (June–August), will increase by 6%. The highest and significant increase in water needs, by 10%, should be expected in August. The estimated increase in water needs of grapevines indicates the need to development sustainable irrigation systems for vineyards in northern Poland.

Most species of Cucurbitaceae respond favorably to irrigation, especially when combined with fertilizers. The effect of drip irrigation combined with nitrogen fertigation in melon grown on a very light soil in Central Poland, during 2013–2015, was evaluated. The field experimental design was a split-plot with four replications. Two factors were studied: (1) irrigation treatments applied in two combinations—drip irrigation + broadcast nitrogen fertilization (control), and drip irrigation + fertigation with nitrogen; (2) two cultivars—Melba and Seledyn. The total marketable yield of fruits, weight of a single fruit, and the concentration of dry matter, total sugars, monosaccharides, ascorbic acid, total carotenoids, and polyphenols were evaluated. Tested factors presented a significant effect both on the yield and nutritive value characteristics. Drip irrigation combined with nitrogen fertigation, comparing to the control, notably improved yields and nutritional value of fruits. Seledyn produced better yields than Melba. This study shows that on very light soil, with low water and nutrient retention capacity, melon should be drip-irrigated and nitrogen-fertigated to obtain the best cultivation results.

Climate warming increases the water needs of plants. The aim of this study was to estimate the water needs of grapevines in central Poland. Water needs were calculated using the crop coefficients method. Reference evapotranspiration was assessed by the Blaney–Criddle’s equation, modified for climate conditions in Poland. Crop coefficients were assumed according to the Doorenbos and Pruitt method. Water needs were calculated using the data from four meteorological stations. Rainfall deficit with the probability occurrence of normal years, medium dry years, and very dry years was determined by the Ostromęcki’s method. Water needs of grapevines during the average growing season were estimated at 438 mm. Upward time trend in the water needs both in the period of May–October and June–August was estimated. Temporal variability in the water needs was significant for all of the provinces. These changes were mainly impacted by a significant increasing tendency in mean air temperature and less by precipitation totals that did not show a clear changing tendency. Due to climate change, vineyards will require irrigation in the near future. The use of resource-efficient irrigation requires a precise estimate of the grapevines’ water needs. The study identified the water requirements for grapevines in central Poland.

Giant miscanthus is a vigorously growing energy plant, popularly used for biofuels production. It is a grass with low soil and water requirements, although its productivity largely depends on complementary irrigation, especially in the first year of cultivation. The aim of the study was to assess the impact of the forecast climate changes, mainly air temperature increase, on the water needs of giant miscanthus during the growing season in 2021–2050 in the Kuyavia region (central Poland). The years 1981–2010 as the reference period were applied. The meteorological data was based on the regional climate change model RM5.1 with boundary conditions from the global ARPEGE model for the SRES A1B emission scenario. Crop evapotranspiration, calculated using the Penman-Monteith method and crop coefficients, was assumed as a measure of water needs. The study results showed that in view of the expected temperature changes, in the forecast period 2021–2050, the giant miscanthus water needs will increase by 10%. The highest monthly increase may occur in August (16%) and in September (23%). In the near future, the increase in water needs of giant miscanthus will necessitate the use of supplementary irrigation. Hence the results of this study may contribute to increasing the efficiency of water use, and thus to the rational management of irrigation treatments and plant energy resources in the Kuyavia region.

The aim of this study was to verify the response of 13 American asparagus cultivars cultivated for green spear on surface postharvest drip irrigation. Irrigation, used to compensate for periodic deficiencies in precipitation, allows for high- and good-quality crops for many species. The field experiment was carried out in 2006–2008 on a very light sandy soil in central Europe (Poland). Irrigation treatments were applied using the tensiometer indications. Water requirements of asparagus were calculated on the base of reference evapotranspiration and crop coefficients. The following evaluations were made: Height, diameter, and number of summer stalks, as well marketable yield, weight, and number of consumption green spears. Drip irrigation applied for 2 years (2006–2007) in the postharvest period had a positive effect on all studied traits in both summer stalks and green spears in 2007–2008. A significant increase in the height, number, and diameter of summer stalks, as well an increase in the marketable yield, weight, and number of green spears was observed for most of the cultivars. In general, postharvest drip irrigation of asparagus cultivated in very light sandy soil significantly contributes to the increase in productivity of American cultivars of this species.

The effect of nitrogen fertigation of two watermelon cultivars grown on the very light soil in the central part of Poland, during 2012–2014, was evaluated. The field experimental design was a split-plot with four replications. The main plot was the drip fertigation with nitrogen applied in two combinations: drip irrigation + broadcasted nitrogen fertilization (DI) used as a control, and drip irrigation + fertigation with nitrogen (DF); where, two cultivars: Bingo and Sugar Baby were used as a split-plot. The phosphorus and potassium fertilizers were applied pre plant in the spring, whereas, three rates of 40 kg ha−1 of nitrogen fertilizer were applied during the growing season. The fertigation was performed using a proportional mixing dispenser. The ripened fruits were harvested progressively as they mature. The marketable fruit yield, the single fruit weight and the number of fruits per plant, were evaluated. Tested factors presented a significant effect in the yield characteristics, further the interaction among the factors was important. DF, comparing to DI, notably improved fruit traits. Bingo cultivar had higher yield than Sugar Baby, but Sugar Baby cultivar produced more fruits than the Bingo under the DF treatment. This study provides the evidence that on a very light soil with low water and nutrients retention capacity the performance of watermelon can be optimized when nitrogen is applied directly through drip irrigation.

Climate changes lead to a rise in air temperature, which significantly increases the water needs of plants. Maintaining crop productivity will increasingly require the use of plant irrigation. The aim of this study was to assess the water needs of grapevines cultivated in the western provinces of Poland. The calculations were made on the basis of temperature and precipitation measurements collected at three meteorological stations in the period 1981–2010. Water needs were calculated as crop evapotranspiration, which was estimated by crop coefficients and reference evapotranspiration, determined using the Blaney–Criddle formula. The rainfall deficit was assessed by Ostromęcki’s method. The tendency to increase the water needs was observed in each subsequent decade of the thirty-year period, both in the whole growing season (May–October), as well as in June–August and July. The highest values of the linear correlation coefficient for the trend of time variability in water needs occurred from June to August. An analysis of water needs and rainfall deficits indicates the need for the additional irrigation of vineyards in western Poland, especially in very dry years and in June–August. Current research results are helpful in designing vineyard irrigation systems and allow an economical and efficient planning of grapevine irrigation.

The aim of the present research was to compare sweet cherry tree water requirements in the vegetation period (IV–X) in the regions of Isparta (Turkey) and Bydgoszcz (Poland). The comparative analysis included precipitation values in the regions of Isparta and Bydgoszcz in the years 1984–2014. The calculation model by Hargreaves modified by Droogers and Allen [5] was applied in order to estimate the reference evapotranspiration (ET0). Potential evapotranspiration, identified with sweet cherry tree water requirements, was determined using the method of plant coefficients proposed by Doorenbos and Pruitt [2]. In each of month considered, higher sweet cherry water requirements occurred in the Isparta region. The highest sweet cherry trees water requirements for the research period were reported in July and they amounted to an average of 238 mm and 118 mm for the Isparta and Bydgoszcz regions, respectively. Sweet cherry tree water requirements throughout were higher by 102% in the region of Isparta than in the region of Bydgoszcz. Higher irrigation requirements in the province of Isparta compared to the region of Bydgoszcz result mainly from the smaller amount of precipitation and differences in the distribution of precipitation during the vegetation period.

The field experiment was carried out in 2016 on sandy soil in the forest nursery Białe-Błota (Bydgoszcz Forest Division, Poland). The effect of sprinkler irrigation on the growth Paulownia Shan Tong trees was investigated. The experiment was established as one factorial. The variability factor was the irrigation: S-sprinkler irrigation and C- without irrigation (control). The process included the controls of growth parameters: tree height, trunk diameter, number and surface of leaves. It was found that the sprinkled seedlings of Paulownia Shan Tong were significantly higher than those growing in the non-irrigated plots. The sprinkler irrigation applied in the experiment resulted in an increase in the number of leaves of the Paulownia and their surface area, which resulted in an increase in biomass yield. By analysing the results of the study on trunk diameter, leaf number and surface, it may be stated that irrigation watering significantly influenced the tested parameters. Irrigation significantly increased the height of Paulownia trees. The positive effect of the usage of sprinkler irrigation may indicate the possibility of effective application of this method in the field cultivation of Paulownia Shan Tong.

The goal of this study was to assess the water needs of elderberry. The investigation included elderberry plants that had been planted in land reclamation areas more than three years earlier. The water needs were evaluated for 5 agro-climatic regions of Poland. The calculations were based on the observation of meteorological conditions in the years 1981-2010 for the period from June 1 to July 31. To determine the water needs, the plant coefficient method was applied. The Blaney-Criddle formula, which was modified for Polish conditions by Żakowicz (2010), was used to calculate the reference evapotranspiration. The plant coefficients of elderberry, adapted to the reference evapotranspiration, were adjusted to Żakowicz’s method. The rainfall deficit with the probability of occurrence: N50%, N25% and N10%, was assessed in accordance with Ostromęcki’s method. The highest water needs of elderberry occurred in central-north-west (264 mm) and central-east (262 mm) Poland, while the lowest (244 mm) in the south-east region. In June, the highest total monthly water needs (119 mm) were noted for south-west Poland, whereas the lowest (107 mm) for the south-east region. In June and July, except for the central-north-west region, an upward time trend of water needs was noted throughout Poland. In June and July, the highest value (135 mm) of rainfall deficit N50% and N25% was estimated for the central-north-west region, while the highest rainfall deficit N10% (269 mm) for central-east Poland. The results of the presented research find application in the planning of irrigation treatments for elderberry in Poland.

The purpose of research was to determine the irrigation effects on the root yield of red beet grown on light soil in different regions of Poland, depending on rainfall amounts during the period July-August. Relationship between the increases of root yield and applying of irrigation was estimated using the Grabarczyk’s formula. The amounts of rainfall in the average dry year, medium dry and very dry were determined by the Ostromęcki’s method. Rainfall deficits in the cultivation of red beet were determined according to the difference between optimum and real precipitation in five meteorological stations. The highest precipitation deficiencies in the red beet crops in July-August were observed in the central Poland, where amounts 51–52, 98 and 118–124 mm, in average dry, medium dry and very dry years, respectively. The highest increases of the root yield obtained using irrigation were estimated also in the central Poland, where amounts 9.26 and 8.96 t ha−1, 17.30 and 17.28 t ha−1, and 20.92 and 22.00 t ha−1 in average dry, medium dry and very dry years, respectively. The increases of red beet yield obtained using irrigation showed the large possibilities of raising its productivity in the field cultivation under optimal water conditions.

The ash-leaved maple (Acer negundo L.) has low habitat requirements, which is why this species is often used in the reclamation of industrial areas. The development of the reclamation plantings depends on the optimal water soil conditions that can be controlled by watering treatments. However, the use of irrigation requires determining the water needs of the cultivated species. The objective of the study was to evaluate the water needs of the ash-leaved maple in the reclamation plantings, in the period of over three years after planting. The water needs of the ash-leaved maple were determined using the crop coefficients method. Potential evapotranspiration was calculated using the Blaney-Criddle's formula that was modified for the Polish conditions by Zakowicz. The water needs of the ash-leaved maple were assessed for five agro-climatic regions of Poland, in the years 1981-2010. The water needs of the ash-leaved maple in the growing period (April-October) were the highest in the C-E (638 mm) and C-N-W (637 mm) regions, and the lowest in the N-E (598 mm) and S-E (601 mm) regions. In July, the highest water needs were noted in the C-N-W region (149 mm) and the lowest in the S-W region (129 mm). In the studied thirty-years period, there was a significant upward trend in the water needs of the ash-leaved maple both during the growing season (except for the C-N-W region) and in July, in all the considered regions.

Asparagus (Asparagus officinalis L.), due to their deep and well-developed root system, are relatively resistant to the water deficits in the soil. On the other hand, asparagus plants grown on the light soil positively respond to the irrigation treatments. The aim of the present study was the determination of water needs of asparagus plants in the different agro-climatic regions of Poland. The calculations of asparagus water requirements, considered as the crop evapotranspiration, based on the precipitation measurements collected during the thirty-year period from 1981 to 2010. The estimations were achieved for the months, including July and August, critical in terms of the amount of water available to the plants. The calculation of asparagus water needs using the plant coefficients was performed. The plant coefficients for asparagus cultivated in the Polish field conditions were determined by Rolbiecki. Published by him calculations based on the long term observations of the irrigated asparagus crop. The reference evapotranspiration was calculated according to Grabarczyk's method. The Grabarczyk's formula was chosen because it allowed estimating the reference evapotranspiration in a simplified way, i.e. based only on the precipitation measurements. The rainfall deficit was considered using the Ostromecki's method. The precipitation deficit in the period from July 1 to August 31 was calculated as the difference between the water needs of asparagus, expressed as the crop evapotranspiration for a considered month and the total precipitation in this month. The water needs of asparagus plants were determined for five agro-climatic regions of Poland with the representative meteorological stations located in Olsztyn, Bydgoszcz, Warszawa, Wroclaw and Krakow. The highest variability of asparagus water requirements was calculated in the central-north-west (C-N-W) region of the Poland. The variation coefficient in July and August was 7.7% and 7.6%, respectively. In contrast, the lowest variability of asparagus water needs were find in the south-west (S-W) and south-east (S-E) region of Poland. The highest water needs of asparagus plants, on average 228 mm, in the period from July to August were noted in the C-N-W and central-east (C-E) region of Poland. The highest rainfall deficit, calculated for medium dry years, average dry years and very dry years, was 91 mm and 89 mm, 157 mm and 166 mm, and 209 mm and 245 mm, respectively, in the C-N-W and C-E region, respectively. Generally, higher precipitation deficiencies were noted in August than in July.

The purpose of the present study was to determine the water needs of bird cherry (Padus avium Mill.) over three years after planting on the reclaimed areas. The estimations were performed for the period of two months, including July and August, which are critical in terms of the amount of water available to the plants. The water requirements of bird cherry plants were calculated in the years 1981-2010 for five agro-climatic regions of Poland with the representative meteorological stations located in Olsztyn, Bydgoszcz, Warsaw, Wroclaw and Krakow. The bird cherry water needs were determined using the plant coefficient method. The plant coefficients for bird cherry trees over three years after planting were adapted to the reference evapotranspiration that was calculated using the Blaney-Criddle's formula, modified for Polish conditions by Zakowicz. The rainfall deficit with the probability of occurrence of average dry years (N-50%), medium dry years (N-25%) and very dry years (N-10%) was determined according to the Ostromecki's method. On average, in the years 1981-2010, in July and August, the highest water needs of bird cherry trees, grown on the reclaimed areas over three years, were estimated in the central-north-west (271 mm) and central-east (270 mm) region of Poland. While, the lowest water requirements of bird cherry (240 mm) in the south-east region of the country was calculated. In August, the highest bird cherry water needs (121 mm) were estimated also in the central-north-west and central-east region of Poland, whereas the lowest water requirements (111 mm) occurred in the south-east region of the country. In each considered region of Poland, in the years 1981-2010, a visible increase in bird cherry water needs in the period of the highest water requirements, was noted. With the exception of the central-north-west region of the country, the temporal variability of bird cherry water needs was significant throughout Poland. The highest increase of the water requirements (by 6.7 mm per every ten-year period) in the south-east region of Poland was found. In the period covering July and August, the highest rainfall deficit, 131 and 133 mm, in the average dry years (N-50%) was noted in the central-east and central-north-west region of Poland, respectively. In the north-east, central-north-west and central-east region of the country, the rainfall deficit in the medium dry years (N-25% ranging from 206 to 214 mm) and very dry years (N-10% ranging from 269 to 300 mm) was higher than in the south-west and south-east region of Poland (N25% ranging from 146 to 159 mm and N-10% ranging from 195 to 211 mm).

The aim of the study was to estimate the water needs of early cultivars of cauliflower (Brassica oleracea L. var. botrytis L.). The calculations, based on the expected changes of air temperature, covered the forecasted thirty-years period, considered from 2021 to 2050. The research include the region of Bydgoszcz located in the central Poland. The forecasted mean monthly values of temperature in the region of central Poland, in the years 2021-2050, according to the climate change scenario for Poland (SRES: A1B), were used in the estimations. The water requirements of cauliflower early cultivars grown on three types of soil that diversified in terms of the water capacity (light soil, medium soil, heavy soil), were considered using two methods: Klatta's method and Press's method. The cauliflower water needs in the growing period, assumed from April to July, were calculated for each year during the considered thirty-years (2021-2050). As the reference period, the thirtyyears interval from 1981 to 2010 was applied. According to the expected changes of climate conditions, the results of study indicate that during the forecasted period (2021-2050), in the central Poland, the water requirements of cauliflower early cultivars will increase by about 6 %. Comparing to the reference period, considered from 1981 to 2010, the water needs of cauliflower early cultivars grown on the medium soil will increase in the forecasted years in the range from 304 to 321 mm On the light (sandy) soil, the water requirements of cauliflower early cultivars, calculated by the Klatta's and Press's methods, in the forecasted period will increase from 349 to 369 mm and from 364 to 385 mm, respectively. While on the heavy (concise) soil, the water needs of cauliflower early cultivars in the forecasted years will increase from 258 to 273 mm and from 243 to 257 mm, according to the Klatta's and Press's method, respectively. During the growing period, the highest water requirements of cauliflower early cultivars were estimated in June: 85-90 mm on heavy soil, 107 mm on medium soil and 123-129 mm on light soil. In the years 2021-2050, in July, should be expected the highest increase of cauliflower early cultivars water requirements (by about 14 %).

The purpose of this study was to estimate the expected effects of sprinkler irrigation, applied depending on the rainfall amounts, on the yield increasing of marketable carrot roots (Daucus carota L.). The experiment was performed on light soil in different regions of Poland at the critical period considered from May 1 st to July 31 st . A straight line relationship between the yield increase and the use of sprinkler irrigation depending on the amount of precipitation was adapted. The carrot roots yield was determined for five agroclimatic regions of Poland. The amount of rainfall in the average dry years (P50 %), medium dry years (P25 %) and very dry years (P10 %) was defined by the Ostromęcki method. The largest precipitation deficit in the cultivation of carrot during the critical period in the average dry years and medium dry years was found in the C-N-W region of Poland. In the very dry years the largest rainfall deficit was in the C-E region of Poland. The smallest precipitation deficiency was noted in the S-E region of Poland. The highest increase of the roots yield, observed as the influence of sprinkler irrigation applied during the average dry years and medium dry years, is expected in the C-N-W region of Poland. In the very dry years the largest raise of the roots yield can be expected in the C-E region of Poland. The predictable production effects of sprinkler irrigation, estimated in the present study, show a great possibility of increasing of carrot roots marketable yield in field cultivation under optimum water conditions.