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Research project (§ 26 & § 27)
Duration : 2018-04-01 - 2021-03-31

Crop simulation models are digital farming tools which provide means to optimize farmer's activities. They capture crop growth and development responses to weather, soil, genetic, and management factors and allow nitrogen (N) fertilizer recommendations, yield forecasting, and climate change impact assessment, provided a sound model parameterization and evaluation using quality data sets. Unfortunately, those are scarce in Austria. Additionally, simulations of leaf canopy development are usually poor, although they are crucial for simulated crop N status. This project aims at (1) investigating the structural differences in leaf canopy simulation of two crop models, (2) parameterizing and evaluating one model for eastern Austria for use in a web-based digital farming tool for improved N fertilizer management, (3) a regional yield forecasting tool for wheat, maize, potato, and sugar beet, and (4) identifying the influence of different model structures on climate change simulations. This project is the first study using detailed scientific field data sets of Austrian crop cultivars and environmental conditions to parameterize two crop simulation models. Data sets for wheat and maize using N fertilizer and sowing date variations are available, further data will be acquired from experiments with different crops. The two contrasting crop models APSIM and SSM are used in this study. SSM is well documented model and easy to parameterize, while APSIM is comparably more complex. First simulations of wheat phenology and yield agreed well with observations. We improved both models' inaccuracy in predicting in-season LAI and N concentrations by detailed model parameterization and implementing new functions. Future work includes the parameterization of other wheat, maize, potato, and sugar beet cultivars for eastern Austria, with focus on leaf canopy development, N fertilizer requirement, and crop yield. All parameterizations will be evaluated using new and independent data sets. Furthermore, a simulation study using different climate change weather data will be conducted. The implications of variation in accuracy of leaf canopy development simulation on adaptation of wheat and maize to future climatic conditions will be discussed.
Research project (§ 26 & § 27)
Duration : 2018-11-01 - 2021-10-31

Ambrosia artemisiifolia L. (Asteraceae) known as common ragweed is an annual herbaceous species native to North America which is not only a troublesome agronomic weed but actually one of the most dominant inducers of pollen allergy. Management options to effectively contain the spread of the plant are limited due to lack of efficacy (mowing, spraying), cost and time (roadside management) or lack of awareness (farmers). In consideration of all these aspects new approaches for managing common ragweed have to be developed. One new approach in weed control is to exploit the potential of weed-suppressing ability of crops themselves, which results from the emission of volatile organic compounds (VOCs).To get a detailed understanding of how crops and weeds can influence each other, the chemical profile of both have to be taken into account, especially as allelopathy has proved to be inducible by various biotic (other plants, pests, pathogens) and abiotic factors (nutrient supply, radiation, water supply etc.). Therefore, the first aim of the study is evaluation of the competition effects of common ragweed upon growth (aboveground/belowground), development, internal nitrogen dynamics, and yield potential of soybean. The idea is to quantify the impact of individual stressors (drought, nutrient deficiendy and shading) on common ragweed and on soybean in pure stands as well as in mixed stands. Additionally, it should be investigated if there is a reinforcing effect of the stressor(s) and common ragweed on soybean. After the quantitative assessment of the standard competition factors the role of volatile organic compounds in the interaction process between soybean and common ragweed should be determined. The main goal is to determine how the chemical profile of non-stressed plants differ from the VOCs emitted from stressed plants and how these VOCs alter the growth patterns of the responding plant (soybean-soybean; ragweed-ragweed; ragweed-soybean; soybean-ragweed). As not only the living plant but also residues of common ragweed in soils could negatively affect seed emergence and plant growth in the third part of the present study the chemical compounds of common ragweed residues and ragweed-leachate as well as their impact on soybean germination and seedling development should be analyzed. The main goal is to define a certain threshold of ragweed residues and a certain minimum concentration of ragweed leachate, respectively below which soybean germination and growth are not affected. The study should give a full assessment of the morphological and biochemical behavior of common ragweed and soybean in single stands and combined under the most important biotic (interspecific completion) and abiotic stress (water, nutrients, radiation) conditions.
Research project (§ 26 & § 27)
Duration : 2017-09-01 - 2019-12-31

Conservation and utilization of soil fertility is among the key objectives of sustainable cropping system intensification. Cover cropping is a well-established and efficient agro-environmental measure for groundwater protection, erosion control and stabilization of soil organic matter content. Currently there is hardly any scientific information available to quantify cover crop induced mobilization of soil nutrients with low mobility and thereby estimate potential positive effects on a subsequent main crop. Based on soil and plant nutrient analyses for 13 different cover crops and a bare soil control from a field trial, a database for cover crop nutrient mobilization will be established and the effect on nutrient uptake and yield of the subsequent main crop will be determined.

Supervised Theses and Dissertations