Serious attention is paid today to the problems of landscape regionalization with respect to its hydrological response. The quantification and the spatial pattern of soil drought indicators (SDI) are considered crucial for a correct hydrological zonation of agricultural lands with regard to water-related phenomena of practical importance, such as drought risk, runoff generation and soil erosion. The paper deals with regional estimation of hydrolimits (field capacity, point of limited availability, wilting point) and water storage capacity (expressed as the difference between the field capacity and the wilting point) of the root zone of agricultural landscape and their interpretation as potential soil drought indicators (SDI). A spatial and pedotransfer approach was applied to the region of the Záhorská nížina Lowland. Relevant outputs (parameters of soil water retention curves) were derived from the data of the Comprehensive Agricultural Soil Survey digital database (KPP DB) using pedotransfer functions (Rosetta model). A spatial processing of model outputs to the form of the regional maps of SDI was performed using GIS tools. SDI were then quantitatively evaluated for (i) individual textural soil units and (ii) individual pedo-ecological regions of Záhorská nížina Lowland respectively. Water storage capacity of soil represents the maximum volume of long-term available water in the effective root zone of cultural crops. To be used as soil-drought indicator, the water storage capacity data should always be interpreted in combination with information about the water contents related to the field capacity and the wilting point. Generally, it is assumed that spatial pattern of SDI is closely related to the soil textural units, while in the case of Záhorská nížina Lowland the segmentation of the landscape to pedo-ecological regions is considered inadequate from hydrological point of view. and V súčasnosti je v kruhoch hydrológov venovaná veľká pozornosť problematike regionalizácie krajiny z hľadiska jej hydrologickej odozvy. Kvantifikácia indikátorov pôdneho sucha (SDI) a poznanie ich priestorovej variability sú kľúčové pre korektné delenie poľnohospodársky využívaných pôd na zóny vo vzťahu k hydrologickým javom s praktickým významom, ako sú sucho, tvorba odtoku a pôdna erózia. Príspevok sa v regionálnej mierke zaoberá odhadom hydrolimitov (poľnej vodnej kapacity, bodu zníženej dostupnosti, bodu vädnutia) a vododržnej kapacity (ako rozdielu v obsahu vody medzi poľnou vodnou kapacitou a bodom vädnutia) koreňovej vrstvy pôd v poľnohospodárskej krajine a ich interpretáciou ako potenciálnych indikátorov pôdneho sucha. Pedotransférový prístup bol využitý pre priestorové spracovanie SDI v rámci regiónu Záhorskej nížiny. Relevantné výstupy (parametre vlhkostných retenčných kriviek) boli odvodené z údajov digitálnej databázy Komplexného prieskumu poľnohospodárskych pôd (KPP DB) využitím pedotransférového modelu Rosetta. Výstupy z modelu boli priestorovo spracované do podoby regionálnych máp indikátorov pôdneho sucha s využitím nástrojov GIS a následne kvantitatívne zhodnotené pre (i) jednotlivé pôdne druhy a (ii) jednotlivé pedo-ekologické regióny Záhorskej nížiny. Vododržná kapacita pôdy reprezentuje maximálny objem vody v koreňovej vrstve pôdy dlhodobo prístupnej pre kultúrne plodiny. Údaje o vododržnej kapacite pôd musia byť pre účel stanovenia potenciálu pôdy z hľadiska jej ohrozenosti suchom (teda ako indikátor pôdneho sucha) interpretované vždy v kombinácii s informáciou o obsahoch vody zodpovedajúcich poľnej vodnej kapacite a bodu vädnutia. Všeobecne možno konštatovať, že priestorová distribúcia indikátorov pôdneho sucha je úzko zviazaná s prirodzenou variabilitou pôdnych druhov, kým segmentácia územia podľa pedo-ekologických regiónov je v prípade regiónu Záhorskej nížiny z hydrologického hľadiska nedostačujúca.
In grasslands where organic and inorganic resources are alternating at scales of individual plants, the transient character is given to certain wetting properties of soil, which then become highly variable both in space and in time. The objective of presented study was to study wetting pattern within two soil horizons at 5-cm and 10-cm depths respectively and to examine how the wetting patterns relate to hydraulic conductivity determined by Minidisc infiltrometer at suction -2 cm, K(-2 cm). This characteristics is implicitly independent on antecedent soil water content (SWC) since it relates to steady infiltration phase but can be influenced by present soil water repellency (SWR). Field measurements were performed on July 27-28, 2010 on the grassland experimental site located near the village Sekule in Southwest Slovakia. The water drop penetration time (WDPT), SWC and tension Minidisc infiltration measurements were carried out on the 0.64 m2 plot in a regular 8 x 8 grid. The results showed that SWR and SWC influence each other and cause correlation between spatial patterns of studied soil wetting characteristics and between characteristics measured at the two soil depths. Further, it was found out, that calculation of K(-2 cm) according to Zhang may cause apparent correlation of K(-2 cm) with antecedent SWC, which is the artificial effect of sorptivity parameter in the equation on steady stage of infiltration process. This pseudocorrelation has disappeared after adopting of Minasny and McBratney (2000) approaches by calculation of K(-2 cm).
The application of Brilliant Blue FCF tracer enables to identify flow types in multi-domain porous systems of soils via analyses of morphologic parameters of stained objects occurring in dye pattern profiles, as they represent the footprint of flow processes which occurred in soil during both the infiltration and the redistribution of dye solution. We analysed the vertical dye pattern profiles exposed for different time lengths, and revealed temporal evolution of dye solution redistribution leading to changes in flow types. The field experiment was performed with the Brilliant Blue tracer (the 10 g l–1 concentration) applied on 1m x 1m surface of the Dystric Cambisol. The top litter horizon had been removed before 100 l of the tracer was applied. Four vertical profiles were excavated on the experimental plot (always 20 cm apart) at different times after the irrigation had been finished: 2 hours (CUT 2), 24 hours (CUT 24), 27 hours (CUT 27) and 504 hours (CUT 504). The analyses of the dyed patterns profiles showed the spatio-temporal changes in the dye coverage, surface area density, average BB concentration, and stained path width, which allowed us to specify three stages of dye solution redistribution history: (i) a stage of preferential macropore flow, (ii) a stage of strong interaction between macropore-domain and soil matrix leading to the generation of heterogeneous matrix flow and fingering flow types, and (iii) a final stage of dye redistribution within the soil body connected with leaching of BB caused by meteoric water. With increasing time, the macropore flow types convert to mostly matrix-dominated FTs in the upper part of the soil profile. These results were supported by soil hydrological modelling, which implied that more than 70% of the soil moisture profiles variability among CUT 2–CUT 504 could be explained by the time factor.