Browsing by Person "Bauerle, Andrea"

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Agrivoltaics mitigate drought effects in winter wheat
(2023) Pataczek, Lisa; Weselek, Axel; Bauerle, Andrea; Högy, Petra; Lewandowski, Iris; Zikeli, Sabine; Schweiger, Andreas
Climate change is expected to decrease water availability in many agricultural production areas around the globe. At the same time renewable energy concepts such as agrivoltaics (AV) are necessary to manage the energy transition. Several studies showed that evapotranspiration can be reduced in AV systems, resulting in increased water availability for crops. However, effects on crop performance and productivity remain unclear to date. Carbon‐13 isotopic composition (δ13C and discrimination against carbon‐13) can be used as a proxy for the effects of water availability on plant performance, integrating crop responses over the entire growing season. The aim of this study was to assess these effects via carbon isotopic composition in grains, as well as grain yield of winter wheat in an AV system in southwest Germany. Crops were cultivated over four seasons from 2016–2020 in the AV system and on an unshaded adjacent reference (REF) site. Across all seasons, average grain yield did not significantly differ between AV and REF (4.7 vs 5.2 t ha−1), with higher interannual yield stability in the AV system. However, δ13C as well as carbon‐13 isotope discrimination differed significantly across the seasons by 1‰ (AV: −29.0‰ vs REF: −28.0‰ and AV: 21.6‰ vs REF: 20.6‰) between the AV system and the REF site. These drought mitigation effects as indicated by the results of this study will become crucial for the resilience of agricultural production in the near future when drought events will become significantly more frequent and severe.
Agrivoltaics: The environmental impacts of combining food crop cultivation and solar energy generation
(2023) Wagner, Moritz; Lask, Jan; Kiesel, Andreas; Lewandowski, Iris; Weselek, Axel; Högy, Petra; Trommsdorff, Max; Schnaiker, Marc-André; Bauerle, Andrea
The demand for food and renewable energy is increasing significantly, whereas the availability of land for agricultural use is declining. Agrivoltaic systems (AVS), which combine agricultural production with solar energy generation on the same area, are a promising opportunity with the potential to satisfy this demand while avoiding land-use conflicts. In the current study, a Consequential Life-Cycle Assessment (CLCA) was conducted to holistically assess the environmental consequences arising from a shift from single-use agriculture to AVS in Germany. The results of the study show that the environmental consequences of the installation of overhead AVS on agricultural land are positive and reduce the impacts in 15 of the 16 analysed impact categories especially for climate change, eutrophication and fossil resource use, as well as in the single score assessment, mainly due to the substitution of the marginal energy mix. It was demonstrated that, under certain conditions, AVS can contribute to the extension of renewable energy production resources without reducing food production resources. These include maintaining the agricultural yields underneath the photovoltaic (PV) modules, seeking synergies between solar energy generation and crop production and minimising the loss of good agricultural land.
Efficiency of phosphorus fertilizers derived from recycled biogas digestate as applied to maize and ryegrass in soils with different pH
(2022) Bach, Inga-Mareike; Essich, Lisa; Bauerle, Andrea; Müller, Torsten
Three phosphorus (P) fertilizer fractions recycled from biogas digestates were tested alone and in combination for their efficiency in two agricultural surface soils with different pH: a silty sandy loam and a clay loam. The experiments were carried out in pots under greenhouse conditions, using mineral triple superphosphate (TSP) as a reference. Maize was cultivated for 50 days, followed by ryegrass cultivation for an additional 84 days in the same soil, without additional fertilization. The variables investigated were above-ground plant biomass production, plant phosphorus concentration and content, and plant available phosphorus concentration in soil. The dry matter (DM) yield of maize was increased by the organic P fertilizers equal to or more than TSP in both soils. In the neutral soil, biomass was almost doubled compared to TSP when using one of the fractions (Struvite containing P-Salt) alone or in combination with dried solid fractions. P concentration in maize cultivated in the neutral soil was not significantly different between the P fertilization treatments. However, associated with biomass increase, the total P content in maize plants was equal to or higher than that with TSP. In the acidic soil, P concentration and total P content in maize plants, as well as the calcium-acetate-lactate extractable P (CAL-P) concentration in soil, were equal to or even higher than TSP. Ryegrass DM yield was unaffected by all P fertilizers, independent of the soil, although P concentration and total P content increased in the acidic soil with all fertilizers. Our results show that recycled P fertilizers from biogas digestates are effective P fertilizer alternatives to mineral TSP for maize cultivation under acidic and neutral soil conditions. The lack of growth effects in ryegrass indicates that recycled P fertilizers do not require changes in weed control. On the other hand, P extraction by ryegrass in overfertilized acidic soils as an option for soil remediation also works in soils fertilized with biogas digestate fractions.
Suitability of recycled organic residues from animal husbandry and bioenergy production for use as fertilizers
(2021) Bauerle, Andrea; Lewandowski, Iris
In recent years, agriculture has been increasingly faced with the acute need to find a more sustainable practice for dealing with nutrient-rich organic side streams. For ecological and economic reasons, pressure is mounting every day to implement an improved utilisation and to close nutrient loops in agriculture to the maximum possible. Pig manure and biogas digestates are suitable as organic fertilisers because they contain essential plant nutrients. They also provide organic matter that contributes to the maintenance of soil fertility. However, their current use is often insufficient. Both residues can be used as fertilisers either directly or following treatment. This can be as simple as solid-liquid separation. A more advanced approach is the precipitation of phosphorus for conversion into phosphate fertilisers ("P-Salts"). The fertilising effect of such innovative P-Salts needs to be investigated in an agronomic context. The same applies for the integration of separated biogas digestates as organic fertilisers into different biomass production systems. The primary objective of this thesis is to establish whether recycled fertilisers from organic residues are comparable to mineral fertilisers and can serve as a suitable substitution. For this purpose, five specific objectives were defined: (1) to determine whether separated biogas digestates can complement or substitute mineral fertilisers and whether/how they affect long-term yield performance in different biomass cropping systems; (2) to ascertain which type of separated biogas digestate is suitable for which biomass production system; (3) to test the effect of two recycled P-Salts on yield and quality of different crops compared to triple superphosphate (TSP); (4) to examine whether the combination of recycled P-Salts with biochar and dried solid digestates results in interaction effects; and (5) to assess whether there are differences in the uptake efficiency of recycled and mineral fertilisers between different crop types. Thus, several experiments were carried out. The fertilising effect of separated biogas digestates on three biomass production systems (perennial grassland, intercropping of triticale and clover grass, silage maize) was investigated in multi-year field experiments in south-west Germany. P-Salt and biochar from pig manure were tested in a greenhouse study with spring barley and faba bean. In a second greenhouse study with ornamentals, the P-Salt from manure, a P-Salt from biogas digestate, and dried solid digestates were assessed. The long-term yield stability of biomass cropping systems fertilised with separated biogas digestates was clearly demonstrated under field conditions. Separated biogas digestates can substitute mineral fertiliser in perennial and intercropping systems. Solid digestates were most suitable for cropping systems with soil tillage where their incorporation into soil is possible. The intercropping of triticale and clover grass was found to be the most stable system, with constantly high biomass yields being maintained using only digestates. For maize, a combined application of digestates and mineral fertiliser proved to be the best option. The P-Salt from manure had the same or even better effects than TSP on spring barley and faba bean. In the experiment with ornamentals, the two P-Salts from manure and digestate had more or less the same effect as TSP on biomass production. These results suggest that both P-Salts have an equivalent fertilisation effect to TSP and can thus replace it as mineral fertiliser. In this thesis, it was possible to achieve competitive yield results with the tested fertilisers, provided that they are integrated in a suitable fertilising strategy. The next step is for the recycled fertilisers to be actually used in agricultural practice - a prerequisite for which being that their implementation has agronomic, practical, ecological and economic advantages. The enhanced use efficiency of N and P already available on farms is challenging but necessary to reduce dependency on both synthesised N fertilisers and imported P fertilisers. This thesis significantly contributes by providing knowledge on the fertilising effect of selected recycled fertilisers necessary for their future implementation in agriculture. Optimised nutrient management and residue treatment using advanced technologies can contribute to the further closing of nutrient cycles. The highest environmental benefits can be realised on farms with excess residues and limited agricultural land. It is therefore highly recommended that these farms improve their current practice by prioritising the implementation of appropriate measures. Sound residue management necessitates strategic planning and capital investments from farmers and companies, but is a crucial step towards the sustainable intensification of cropping systems and resilient future agriculture.