Amadeusz Walczak

This study aims to determine the effects of differences in variety and irrigations levels on potato yield (appropriate humidity, temperature, shading the plants from the sun if necessary) on potato yield in greenhouse conditions. Functions of potato production with respect to water use were developed for five dates of measurements of plant growth, in relation to the various vegetation phases. On the basis of potato vegetation phases, the potato water demand was determined. An experiment was conducted using the randomized sub-block method. The first order factor were the two varieties of potato that were grown under drip irrigation with three water regimes as a second factor experiment: level 1 (pF 2.7), level 2 (pF 2.5) and level 3 (pF 2.2). The variety had a significant effect on the weight of potato tubers. The irrigation level had only a significant effect on the total potato biomass. The potato harvest date had a significant effect on both of the examined treatments. The growth dynamics of the aboveground part and potato tubers were the highest in conditions of constant level 1. Regardless of the variety studied, on level 3 caused a reduction in potato biomass production.The highest water consumption was observed during the tuber potato growth period to flowering. The values were varied from 0.39 l/pot day level 1 (in both investigated cultivars) to 0.99 l/ pot/day (humidity level 3 for Julinka cultivar) in July. The most intensive increase in water consumption was observed at the level 3. The average W index of the average daily water dose calculated for Denar cultivar amounted 0.40 l day⁻¹ in the first period (O1) to 0.79 l day⁻¹ in the fifth period (O5) and for Julinka cultivar 0.49 l day⁻¹ (O1) to 0.92 l day⁻¹ (O5). Stress due to water shortage and/or excessive levels of water in the soil negatively influenced the yield of potato tuber. Potato varieties reacted differently to soil water content.

The study was aimed at the determination of the dynamics of spatial distribution of moisture front, caused by pointwise application of water under conditions of high pressure. This was effected through a series of simulations of water injection to a porous material with particle size distribution corresponding to that of sand. The study was composed of six independent experimental series in which the sand monolith was supplied with water doses of 250, 500, 750, 1000, 1250, and 1500 cm³ under pressure (4 bar). At the same time, measurements of volumetric moisture were conducted with the use of TDR sensors, which were positioned within the soil in a regular grid pattern. It was demonstrated that the primary cause of water movement at the moment of injection is the pressure potential gradient of water molecules. The spatial reach of moisture change in relation to the injected water dose was also defined. It was also observed that in the course of water injection there is a risk of disturbing the structure of the porous material. The correctness of the adopted method was verified through the calculation of the water balance.

The paper concerns evaluation of the exploitation of the world's water resources for irrigating field crops. It was determined that the volume of water used in 2020 in all sectors of the economy in relation to the world's freshwater resources will amount to 31 to 38% of the available resources....

Potato is a plant with high water requirements. This factor affects not only the weight of potato tubers but also their quality parameters. In order to achieve quantity and quality goal, it is helpful if we apply the principles of precision agriculture, which also contributes to sustainable management of environmental resources. Accurate identification of the water requirements of crops is the basis for determining optimal irrigation doses and dates. After their application, it is possible to assess the effectiveness of irrigation treatments and their impact on the air-water conditions in soil with a root system. The aim of the presented study was to analyse the influence of volumetric soil moisture diversity on the vegetation of early potato varieties. Two potato varieties were subject to investigation: Denar and Julinka. Pot experiments were carried out at the Department of Horticulture of Wroclaw University of Environmental and Life Sciences. Three variants were analysed: one with a low water content in the soil (pF 2.7), one with the optimal water content (pF 2.5) and one with a high water content (pF 2.2). The basis for the selection of the frequency and application rate of water doses was soil moisture measured with an SM150-Kit set. Volumetric moisture was measured with a TDR apparatus. It was found that the water requirements of both potato varieties differ and increase along with the development of the aboveground and underground parts. Moreover, it was shown that the irrigation requirements of cv. Julinka are higher than those of Denar (31.4–33.0% higher), depending on the adopted variant. The research also showed that the most effective method of potato cultivation is to maintain soil moisture at a lower level. This should be taken into account in regions where the cultivation of this species uses supplementation of the water requirements by irrigation.

The following topics are dealt with: permittivity measurement; soil; water; moisture measurement; calibration; time-domain reflectometry; dielectric relaxation and clay.

The paper presents an analysis of applicability of dielectric sensors for the description of water movement in irrigated soil. An innovative method of irrigation is analysed, consisting in high pressure injection of water to soil. Thanks to this, water can be supplied within a short time (1-3 seconds) at doses required for a single plant, e.g. from 300 to 700 ml. Water injection is performed by means of a mobile platform. Sensors of LP/ms (Labolatory Probe / moisture salinity) type were used for empirical determination of the initial condition in a mathematical model based on the Richards equation. That equation is usually used for the simulation of water flow in porous media. As it is a differential equation, its solution requires that an initial condition is given. In the case under consideration, that condition was the description of water state in the vicinity of the point of water injection. The state of soil water was determined with the help of sensors that allow continuous and basically non-invasive measurement of volumetric moisture. That value was converted, using a function type relation (pF curve), into the matric potential. This allowed the calculation of the total potential which is the value modelled in the predictive equation. It was demonstrated that the use of sensors of LP/ms type allows correct determination of the initial condition in the mathematical model describing water movement in soil irrigated with the injection method.

W pracy wykazano wpływ gęstości pomiarów na dokładność wyznaczania powierzchniowego rozkładu wilgotności objętościowej w wierzchniej warstwie gleby. Do analiz zastosowano metody geostatystyczne, których wykorzystanie poprzedzono wstępną oceną klasycznych miar statystycznych. Po sprawdzeniu warunku stacjonarności zbudowano semiwariogramy empiryczne z najlepiej dopasowanymi modelami matematycznymi. Wykorzystano je podczas procedury krigingu, w celu sporządzenia powierzchniowych rozkładów wilgotności. Na podstawie badań polowych przeprowadzonych w miejscowości Sarbinowo położonej na terenie gminy Mielno wykazano, że zwiększenie dokładności określenia rozkładu wilgotności jest istotne, gdy „oczko” siatki punktów pomiarowych maleje do 1 m. Powierzchniowe zagęszczanie pomiarów wiąże się ze zwiększeniem pracochłonności badań i nie powoduje istotnych zmian w dokładności wyznaczenia rozkładu wilgotności.