Analyses of the densities below the two drip hose positions showed that the soil underneath the surface irrigation had an average density of 1.3 g/cm³ compared to 1.7 g/cm³ underneath the underground irrigation. This difference is significant. The density differences can also explain why, for underground irrigation methods, the root density below the soil surface was not significantly higher than with above-ground irrigation methods or without any irrigation at all. In the loose top soil layer, however, surface irrigation had a positive influence on the number of fine roots there. Outlook The method of analyzing the side wall of a sample soil block provided interesting findings that help explain the influence of the drip hose position and the type of fertilizer application on yield and quality. However, any analysis must also take into account the huge variability of individual hop plants. This is necessary because it has not yet been possible to repeat the tests described above for 20 samples which would allow for the averaging-out of such individual plant variations.
4.6
Investigation of the hop yields a function of the amount and timing of nitrogen fertilization
Team:
A. Baum (Bachelor Thesis) S. Arnold (Bachelor Thesis) J. Stampfl
Collaboration:
Prof. Dr. T. Ebertseder, Fakultät Nachhaltige Agrar- und Energiesysteme, (Faculty of Sustainable Agriculture and Energy Systems) Hochschule Weihenstephan-Triesdorf July 2019 to November 2019
Duration:
Background and objectives of the project Between 2017 and 2019, the Bavarian State Research Center for Agriculture conducted extensive N-fertilization tests as part of the project, "Improving nutrient efficiency in hops through fertilization systems with fertigation." In these experiments, different amounts and variations of the timing of nitrogen fertilization resulted in yield variations. To better understand these differences from a plant physiology perspective, in 2019, two bachelor theses examined the differences in yield and the differences in the seasonal plant evolution as a function of the type and timing of fertilization for Perle and Herkules. Methods The investigations were carried out at two locations in 2019. One was planted with Perle, the other with Herkules. Figure 4.14 shows the fertilization regimen for the Perle site, and Figure 4.15, the one for the Herkules site. At both locations, controls without N-fertilization (A) served as references, as did a plot fertilized with three equal rounds of granulated fertilizer (B). For the fertigated plants (C to F), one-third of the fertilizer requirement was administered in the form of granulated fertilizer and two-thirds via irrigation. The fertigated plants had different start dates for their 6-week fertigation period.
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