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  • Author: Andreas Bauer x
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Influence of tillage depth of a cultivator on the incorporation of crop residues of winter barley in a chernozem soil

Summary

Although crop residues contribute to erosion control, the influence of the tillage depth (TD) on their incorporation has not been studied extensively. The main objective of this study was to determine the differences in the amount and distribution of incorporated crop residues and surface residue coverage if the TD of a cultivator is varied (0.10, 0.20, or 0.30 m). The experiment was carried out on a chernozem soil with winter barley residues in 2016 in Groß-Enzersdorf (Lower Austria). Individual soil cores, each 0.05 m long, were removed using a special device. No significant differences were observed for the incorporated crop residues up to a depth of 0.35 m between the three TDs. The mean values of the incorporated crop residues at a TD of 0.10, 0.20, or 0.30 m were 11.64, 13.30, and 10.82 t/ha, respectively. The distribution of crop residues in the individual depth segments (DSs) showed a main concentration of more than 90% at a depth of 0.10 m and a significant decrease in deeper layers. This stratification was independent of the TD. Therefore, a shallower TD is sufficient for straw management on a chernozem soil in the production area of Marchfeld, which also enables a reduction in draft and, consequently, fuel consumption and processing costs.

Open access
Effects of cold winters and roost site stability on population development of non-native Asian ring-necked parakeets (Alexandrinus manillensis) in temperate Central Europe – results of a 16-year census

Abstract

Asian ring-necked parakeets (Alexandrinus manillensis, formerly Psittacula krameri, hereafter RNP) first bred in Germany in 1969. Since then, RNP numbers increased in all three major German subpopulations (Rhineland, Rhine-Main, Rhine-Neckar) over the period 2003-2018. In the Rhine-Neckar region, the population increased to more than fivefold within only 15 years. Interestingly, there was no significant breeding range expansion of RNP in the period 2010-2018. In 2018, the total number of RNP in Germany amounted to >16,200 birds. Differences in RNP censuses between years were evident. Surprisingly, cold winters (extreme value, −13.7 °C) and cold weather conditions in the breeding season (coldest month average, −1.36 °C) were not able to explain between-year variation. This finding suggests that in general winter mortality is low - with exceptions for winters 2008/2009 and 2009/2010, and a population-relevant loss of broods is low in our study population. Surprisingly, the social behaviour in terms of spatio-temporal stability of roost sites could well explain positive and negative population trends. Years of spatially stable and regularly used roost sites seem to correlate with increasing population sizes. In contrast, known shifts of RNP among different roost sites or the formations of new roost sites by split are related to population stagnation or a decrease in numbers. Climate change may lead to further range expansion as cities not suitable yet for RNP may become so in the near future.”

Open access