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  • Author: Margarita Himmelbauer x
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Open access

Margarita Himmelbauer, Willibald Loiskandl and Svetla Rousseva

Spatial root distribution and water uptake of maize grown on field with subsoil compaction

Soil compaction in agricultural areas inhibits plant root growth through increased mechanical resistance, altered water and nutrient supply. The main objective of this study was to evaluate spatial distribution of roots and its effect on water uptake of maize grown on field with subsoil compaction. Two treatments were examined: complex melioration consisting of deep loosening in combination with drainage and control without applied meliorations. Root observations were conducted on vertical and superposed horizontal planes covered with a 2 cm grid short after silking. Root distributions expressed as index of density and/or dry mass density were estimated down to 1 m soil depth and with a distance to a plant base. For analysis of root distribution pattern on the horizontal planes, a Variance to Mean Ratio (VMR) test was applied. Soil water monitoring were conducted during the vegetation period. On the vertical planes, root densities were similar in the topsoil of both treatments, but the results were significantly higher in the subsoil of the meliorated one showing deeper allocation of root density. In contrast, the control had more squares with lots of roots (i.e. higher indexes) just at the top- subsoil boundary owing to bunching of roots in macropores. The horizontal planes in the control generally consisted larger areas without visible roots and thus great distances for water and nutrient transmission, especially in the subsoil. The estimated VMR also pointed toward different levels of root clustering. Consequently, an inhibited water extraction from the subsoil in the control, a delay in crop ontogenesis and a less biomass production was established during the observed period.

Open access

Margarita L. Himmelbauer, Violeta Vateva, Ljudmila Lozanova, Willibald Loiskandl and Svetla Rousseva

Abstract

Water erosion has been recognized as a major soil degradation process worldwide. This is of special relevance in the semi-arid areas of South Bulgaria with long periods of drought along with severe rainfall events. The main objective of this study was to evaluate the applicability of Bromus innermis L. and Lotus corniculatus L. for soil protection purposes under different site conditions. The site parameters considered were slope, fertilization and a range of soil physical parameters. The plant parameters were canopy cover, biomass, and root morphological characteristics. The experiment includes plots without and with eleven rates of NPK fertilization on gentle (6o) and steep slopes (12o). It was observed that the effect of fertilization on shoot and root growth was stronger on the gentle than on the steep slopes. The biomass accumulation was more sensitive to N than the PK fertilizer applications. The increase of the root density with increasing fertilization rates was more pronounced for the mass than for length or surface area. A significant effect on root diameter was found only for the variants with the highest N application. Treatments with the highest root mass density on both slopes showed the greatest potential for reducing erosion.

Open access

Willibald Loiskandl, Graeme Buchan, Wolfgang Sokol, Viliam Novak and Margarita Himmelbauer

Calibrating electromagnetic short soil water sensors

The use of electromagnetic (EM) soil moisture probes is proliferating rapidly, in two broad domains: in field and laboratory research; and in strongly practical applications such as irrigation scheduling in farms or horticultural enterprises, and hydrological monitoring. Numerous commercial EM probes are available for measurement of volumetric water content (θv), spanning a range of measurement principles, and of probe dimensions and sensing volumes. However probe calibration (i.e. the relationship of actual θv to probe electrical output) can shift, often substantially, with variations in parameters such as soil texture, organic matter content, wetness range, electrical conductivity and temperature. Hence a single-valued, manu-facturer-supplied calibration function is often inadequate, forcing the user to seek an application-specific calibration. The purpose of this paper is to describe systematic procedures which probe users can use to check or re-determine the calibration of their selected probe(s). Given the wide diversity of operating principles and designs of commercially-available EM probes, we illustrate these procedures with results from our own calibrations of five different short probes (length of 5 to 20 cm). Users are strongly recommended to undertake such calibration checks, which provide both a) pre-use experience, and b) more reliable in-use data.

Open access

Marek Rodný, Reinhard Nolz, Viliam Novák, Hana Hlaváčiková, Willibald Loiskandl and Margarita Himmelbauer

Abstract

The aim of this study was to present and validate an alternative evapotranspiration calculation procedure that includes specific expression for the aerodynamic resistance. Calculated daily potential evapotranspiration totals were compared to the results of FAO56 procedure application and to the results of measurements taken with a precision weighing lysimeter permanently grown with irrigated, short grass. For the examination period from March 17 through October 31, 2011, it was found that daily potential evapotranspiration estimates obtained by both calculation procedures fitted well to the lysimeter measurements. Potential evapotranspiration daily totals calculated with the use of the proposed aerodynamic resistance calculation procedure gave better results for days with higher evapotranspiration, compared to the FAO56 method. The most important is that the approach based on the proposed alternative aerodynamic resistance could be effectively used even for a wide variety of crops, because it is not limited to any particular crop.

Open access

Monika Sobotik, Tobias Graf, Margarita Himmelbauer, Gernot Bodner, Andreas Bohner and Willibald Loiskandl

Zusammenfassung

Im Rahmen der Tagung „Wurzel und Rhizosphäre: Ökophysiologie, Humushaushalt und Bodenmanagement” im September 2015 wurden Wurzelfreilegungen von Hopfen und Mais in Wolnzach (Bayern) durchgeführt. Das Hauptziel der Untersuchungen war, die Möglichkeiten und den Wert von Wurzelfreilegungen im Feld zu demonstrieren. Für die Hopfenfreilegungen konnten die sichtbaren oberirdischen Unterschiede auch durch die Bewurzelungsweise erklärt werden. Der Einfluss der Bewässerung auf das Wurzelwachstum wurde ebenfalls untersucht. Die schwächer entwickelten Hopfenpflanzen wiesen eine Wurzeltiefe von ca. 130 cm auf, während die Wurzeln der gut entwickelten Pflanzen bis in eine Tiefe von 370 cm verfolgt werden konnten. Weiters wurden Maispflanzen bei konservierender Bodenbearbeitung mit Direktsaat untersucht. Im Gegensatz zu anderen Standorten konnten mehr Sprosswurzeln und lange Seitenwurzeln bis in eine Bodentiefe von 140 cm gefunden werden.