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Gewählte Doctoral Thesis:

Gernot Bodner (2007): COVER CROPPING IN WATER LIMITED ENVIRONMENTS. A field and modelling study of hydrological and soil structural effects of cover crops and their impact on the water balance.
Doctoral Thesis, BOKU-Universität für Bodenkultur, pp 137. UB BOKU obvsg FullText

Data Source: ZID Abstracts
Abstract:
Cover cropping is a common agro-environmental instrument for soil and groundwater protection. The objective of this study was to assess the risk of soil water depletion by cover crops in a semi-arid environment to improve management for water limited conditions. Aboveground biomass, soil cover and rooting parameters of phacelia, hairy vetch, rye and mustard were characterized. Soil water status under the cover crops and a fallow control was monitored with a field measurement site and infiltration in the macropore range was investigated in detail. Water dynamics were analysis using the FAO Dual Crop Coefficient method and the model HYDRUS 1D. Mustard was most stable under dry conditions with an intense vertical and lateral root system. Vetch had a low rooting density, but a homogeneous depth distribution of roots that could sustain a high biomass growth. The root system of phacelia was intense near the stem base with a high decrease in the vertical and horizontal direction. Rye had only low soil cover before winter, but provided a high root biomass and dense rooting of the soil. Cover crops showed a higher cumulative evapotranspiration compared to fallow under dry conditions in autumn. Plant transpiration accounted for only 17.6 % to 52.6 % of total evapotranspiration. Soil moisture differences to fallow during cover crop growth were reduced over winter to 2.8 % in spring. Water infiltration in the macropore range showed high temporal and spatial variability. A certain stabilization of macropores over winter was found for the cover crops. The study showed that cover cropping in a semi-arid region is feasible without higher risk of yield losses due to water storage depletion. Stabilization of soil structure related hydraulic properties over winter and the reduction of evaporation losses in late summer by plants with a fast canopy cover contribute to equilibrate potential higher water extraction from deep soil layers during the main growing period of the cover crops.


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