Institut für Kulturpflanzenwissenschaften

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Assessing the efficiency and heritability of blocked tree breeding trials
(2024) Piepho, Hans-Peter; Williams, Emlyn; Prus, Maryna
Progeny trials in tree breeding are often laid out using blocked experimental designs, in which families are randomly assigned to plots and several trees are planted per plot. Such designs are optimized for the assessment of family effects. However, tree breeders are primarily interested in assessing breeding values of individual trees. This paper considers the assessment of heritability at both the family and tree levels. We assess heritability based on pairwise comparisons among individual trees. The approach shows that there is considerable heterogeneity in pairwise heritabilities, primarily due to the differences in both genetic as well as error variances among within- and between-family comparisons. Our results further show that efficient blocking positively affects all types of comparison except those among trees within the same plot.
Assessment of different methods to determine NH₃ emissions from small field plots after fertilization
(2025) Götze, Hannah; Brokötter, Julian; Frößl, Jonas; Kelsch, Alexander; Kukowski, Sina; Pacholski, Andreas Siegfried; Anderson, William A.
Ammonia (NH₃) emissions affect the environment, climate and human health and originate mainly from agricultural sources like synthetic nitrogen fertilizers. Accurate and replicable measurements of NH₃ emissions are crucial for research, inventories and evaluation of mitigation measures. There exist specific application limitations of NH₃ emission measurement techniques and a high variability in method performance between studies, in particular from small plots. Therefore, the aim of this study was the assessment of measurement methods for ammonia emissions from replicated small plots. Methods were evaluated in 18 trials on six sites in Germany (2021–2022). Urea was applied to winter wheat as an emission source. Two small-plot methods were employed: inverse dispersion modelling (IDM) with atmospheric concentrations obtained from Alpha samplers and the dynamic chamber Dräger tube method (DTM). Cumulative NH₃ losses assessed by each method were compared to the results of the integrated horizontal flux (IHF) method using Alpha samplers (Alpha IHF) as a micrometeorological reference method applied in parallel large-plot trials. For validation, Alpha IHF was also compared to IHF/ZINST with Leuning passive samplers. Cumulative NH₃ emissions assessed using Alpha IHF and DTM showed good agreement, with a relative root mean square error (rRMSE) of 11%. Cumulative emissions assessed by Leuning IHF/ZINST deviated from Alpha IHF, with an rRMSE of 21%. For low-wind-speed and high-temperature conditions, NH3 losses detected with Alpha IDM had to be corrected to give acceptable agreement (rRMSE 20%, MBE +2 kg N ha−1). The study shows that quantification of NH₃ emissions from small plots is feasible. Since DTM is constrained to specific conditions, we recommend Alpha IDM, but the approach needs further development.
Bioenergy potential of Europe's perennial and biennial wildflowers: a combustion performance benchmark
(2025) von Cossel, Moritz; Hieber, Caroline; Iqbal, Yasir; Berwanger, Eva; Lebendig, Florian; Müller, Michael; Jablonowski, Nicolai David; von Cossel, Moritz; Biobased Resources in the Bioeconomy (340b), University of Hohenheim, Stuttgart, Germany; Hieber, Caroline; Biobased Resources in the Bioeconomy (340b), University of Hohenheim, Stuttgart, Germany; Iqbal, Yasir; College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha, China; Berwanger, Eva; Biobased Resources in the Bioeconomy (340b), University of Hohenheim, Stuttgart, Germany; Lebendig, Florian; Institute of Energy Materials and Devices, IMD‐1: Structure and Function of Materials, Forschungszentrum Jülich GmbH, Jülich, Germany; Müller, Michael; Institute of Energy Materials and Devices, IMD‐1: Structure and Function of Materials, Forschungszentrum Jülich GmbH, Jülich, Germany; Jablonowski, Nicolai David; Institute of Bio‐ and Geosciences, IBG‐2: Plant Sciences, Forschungszentrum Jülich GmbH, Jülich, Germany
The European Commission prioritizes addressing environmental issues like agrobiodiversity loss within a thriving bioeconomy's defossilization. This study investigates eight native European herbaceous flowering wild plant species (WPS) like common tansy (Tanacetum vulgare L.) and wild teasel (Dipsacus fullonum L.) as co‐substrates for pellet combustion, aiming for more biodiversity‐friendly bioenergy cropping systems. A long‐term field trial in southwest Germany examined dry matter (DM) yield and biochemical composition's influence on combustion properties for these WPS and two common bioenergy crops, Miscanthus (Miscanthus x giganteus Greef et Deuter) and Sida (Sida hermaphrodita L. var. Rusby), over two growing seasons. All eight WPS showed suitable combustion properties, comparable to Sida, with significantly higher ash melting temperatures than Miscanthus. This is largely attributed to elevated calcium (5.6–15.3 mg g−1 DM) and magnesium (0.6–2.4 mg g−1 DM) contents. A consistent WPS biomass composition is suggested by no significant year effect. Additionally, lower SO2 and HCl fugacity indicated more environmentally friendly combustion than Miscanthus. However, only a few WPS matched Miscanthus's high DM yield (6.0–12.3 Mg ha−1). This underscores the need for broader WPS investigation to find effective combined solutions for bioenergy and rural environmental protection.
Bird species richness and diversity responses to land use change in the Lake Victoria Basin, Kenya
(2024) Mugatha, Simon M.; Ogutu, Joseph O.; Piepho, Hans-Peter; Maitima, Joseph M.
The increasing demand for cultivated lands driven by human population growth, escalating consumption and activities, combined with the vast area of uncultivated land, highlight the pressing need to better understand the biodiversity conservation implications of land use change in Sub-Saharan Africa. Land use change alters natural wildlife habitats with fundamental consequences for biodiversity. Consequently, species richness and diversity typically decline as land use changes from natural to disturbed. We assess how richness and diversity of avian species, grouped into feeding guilds, responded to land use changes, primarily expansion of settlements and cultivation at three sites in the Lake Victoria Basin in western Kenya, following tsetse control interventions. Each site consisted of a matched pair of spatially adjacent natural/semi-natural and settled/cultivated landscapes. Significant changes occurred in bird species richness and diversity in the disturbed relative to the natural landscape. Disturbed areas had fewer guilds and all guilds in disturbed areas also occurred in natural areas. Guilds had significantly more species in natural than in disturbed areas. The insectivore/granivore and insectivore/wax feeder guilds occurred only in natural areas. Whilst species diversity was far lower, a few species of estrildid finches were more common in the disturbed landscapes and were often observed on the scrubby edges of modified habitats. In contrast, the natural and less disturbed wooded areas had relatively fewer estrildid species and were completely devoid of several other species. In aggregate, land use changes significantly reduced bird species richness and diversity on the disturbed landscapes regardless of their breeding range size or foraging style (migratory or non-migratory) and posed greater risks to non-migratory species. Accordingly, land use planning should integrate conservation principles that preserve salient habitat qualities required by different bird species, such as adequate patch size and habitat connectivity, conserve viable bird populations and restore degraded habitats to alleviate adverse impacts of land use change on avian species richness and diversity.
Breeding progress of nitrogen use efficiency of cereal crops, winter oilseed rape and peas in long-term variety trials
(2024) Laidig, Friedrich; Feike, T.; Lichthardt, C.; Schierholt, A.; Piepho, Hans-Peter
Breeding and registration of improved varieties with high yield, processing quality, disease resistance and nitrogen use efficiency (NUE) are of utmost importance for sustainable crop production to minimize adverse environmental impact and contribute to food security. Based on long-term variety trials of cereals, winter oilseed rape and grain peas tested across a wide range of environmental conditions in Germany, we quantified long-term breeding progress for NUE and related traits. We estimated the genotypic, environmental and genotype-by-environment interaction variation and correlation between traits and derived heritability coefficients. Nitrogen fertilizer application was considerably reduced between 1995 and 2021 in the range of 5.4% for winter wheat and 28.9% for spring wheat while for spring barley it was increased by 20.9%. Despite the apparent nitrogen reduction for most crops, grain yield (GYLD) and nitrogen accumulation in grain (NYLD) was increased or did not significantly decrease. NUE for GYLD increased significantly for all crops between 12.8% and 35.2% and for NYLD between 8% and 20.7%. We further showed that the genotypic rank of varieties for GYLD and NYLD was about equivalent to the genotypic rank of the corresponding traits of NUE, if all varieties in a trial were treated with the same nitrogen rate. Heritability of nitrogen yield was about the same as that of grain yield, suggesting that nitrogen yield should be considered as an additional criterion for variety testing to increase NUE and reduce negative environmental impact.
Comparative ungulate diversity and biomass change with human use and drought: implications for community stability and protected area prioritization in African savannas
(2025) Bartzke, Gundula S.; Ogutu, Joseph O.; Piepho, Hans‐Peter; Bedelian, Claire; Rainy, Michael E.; Kruska, Russel L.; Worden, Jeffrey S.; Kimani, Kamau; McCartney, Michael J.; Ng'ang'a, Leah; Kinoti, Jeniffer; Njuguna, Evanson C.; Wilson, Cathleen J.; Lamprey, Richard; Hobbs, Nicholas Thompson; Reid, Robin S.
Drought and human use may alter ungulate diversity and biomass in contrasting ways. In African savannas, resource‐dependent grazers such as wildebeest (Connochaetes taurinus) and zebra (Equus quagga) may decline or disperse as resources decline, opening space for more drought‐tolerant species such as gazelles (Eudorcas and Nanger) and impala (Aepyceros melampus). This shift can increase species richness, evenness, and overall ungulate diversity. Although higher diversity may stabilize ungulate communities, it may be associated with lower biomass (the total body mass of all individuals in a community), which in turn affects vegetation structure and composition, nutrient cycling, energy flows, and other organisms in savannas. While ungulate biomass often declines during drought or in areas of intense human use, the effects on diversity changes under low‐to‐moderate human use remain less clear. Our fine‐scale censuses in the Maasai Mara National Reserve and adjacent pastoral lands in Kenya showed that ungulate biomass declined more than diversity in the 1999 drought year. In the normal rainfall year of 2002, diversity peaked along the reserve boundary, but species richness leveled off in the drought year. Biomass peaked in the reserve in both census years, and migratory ungulates moved further into the reserve in the drought year, where diversity declined. These findings suggest that core protected areas are crucial for maintaining ungulate biomass, while transition zones from protected and pastoral lands support higher diversity unless drought reduces species richness.
Composting and fermentation: mitigating hop latent viroid infection risk in hop residues
(2024) Hagemann, Michael Helmut; Treiber, Charlotte; Sprich, Elke; Born, Ute; Lutz, Kathrin; Stampfl, Johannes; Radišek, Sebastjan
Hop cultivation, integral to the brewing industry, faces challenges from viroids, especially the citrus bark cracking viroid (CBCVd) but also the hop latent viroid (HLVd) influences hop cone quality. We focused on the degradation kinetics of HLVd thereby covering compost, silage, and digestate made from hop residues. In this study, HLVd serves as a model for understanding CBCVd, which causes significant stunting and yield losses in European hop crops. Composting experiments revealed that although composting significantly lowers HLVd levels, complete degradation within 7 weeks is not guaranteed, with loose compost showing a more rapid reduction than compacted variants. Infectivity experiments conducted using inocula obtained from HLVd-infected hop plant residues exposed to composting, ensiling, and biogas digestate did not result in the transmission of HLVd to viroid-free plants. Also extracting and analyzing the soil-root mixture of plants inoculated with HLVd-infected hop residues did not show evidence for viroid persistence. Degradation experiments further differentiated between the physiochemical and biological influences on viroid and viroid-like random RNA stability, showing that higher temperatures of 50 °C enhance degradation over 40 °C, and pH levels of 5 or 7 are slowing degradation. In contrast deionized water or a pH of 4 or 9 enhances viroid degradation. Adding extracts from digestate accelerated the process indicating a role of biological activity. Interestingly, a viroid-like random RNA with similar physiochemical properties, showed to degrade faster compared to HLVd, suggesting high robustness of the actual viroid secondary structure. These findings offer valuable insights into managing HLVd in hops and potentially other crops, highlighting effective strategies to mitigate viroid spread, and contributing to broader understanding of RNA degradation in agriculture.
Description and prediction of copper contents in soils using different modeling approaches - results of long‐term monitoring of soils of northern Germany
(2022) Ludwig, Bernard; Klüver, Karen; Filipinski, Marek; Greenberg, Isabel; Piepho, Hans‐Peter; Cordsen, Eckhard
Background: Different regression approaches may be useful to predict dynamics of copper (Cu), an essential element for plants and microorganisms that becomes toxic at increased contents, in soils. Aim: Our objective was to explore the usefulness of mixed-effects modeling and rule-based models for a description and prediction of Cu contents in aqua regia (CuAR) in surface soils using site, pH, soil organic carbon (SOC), and the cation exchange capacity (CEC) as predictors. Methods: Three sites in northern Germany were intensively monitored with respect to CuAR and SOC contents, pH, and CEC. Data analysis consisted of calibrations using the entire data set and of calibration/validation approaches with and without spiking. Results: There was no consistent temporal trend, so data could be combined for the subsequent regressions. Calibration using the entire data set and calibration/validation after random splitting (i.e., pseudo-independent validation) were successful for mixed-effects and cubist models, with Spearman's rank correlation coefficients rs ranging from 0.83 to 0.91 and low root mean squared errors (RMSEs). Both algorithms included SOC, CEC, and pH as essential predictors, whereas site was important only in the mixed-effects models. Three-fold partitioning of the data according to site to create independent validations was again successful for the respective calibrations, but validation results were variable, with rs ranging from 0.04 to 0.76 and generally high RMSEs. Spiking the calibration samples resulted in generally marked improvements of the validations, with rs ranging from 0.45 to 0.67 and lower RMSEs. Conclusions: Overall, the information provided by SOC, pH, and CEC is beneficial for predicting CuAR contents in a closed population of sites using either mixed-effects or cubist models. However, for a prediction of CuAR dynamics at new sites in the region, spiking is required.
Detection and persistence of citrus bark cracking viroid and other viroids in citrus peel oils for agricultural applications
(2025) Jagani, Swati; Born, Ute; Winterhagen, Patrick; Schrader, Gritta; Hagemann, Michael H.; Jagani, Swati; University of Hohenheim, Production Systems of Horticultural Crops, Emil-Wolff-Str. 25, 70599, Stuttgart, Germany; Born, Ute; University of Hohenheim, Production Systems of Horticultural Crops, Emil-Wolff-Str. 25, 70599, Stuttgart, Germany; Winterhagen, Patrick; State Education and Research Centre of Viticulture and Horticulture, Institute for Plant Protection, Breitenweg 71, 67435, Neustadt, Germany; Schrader, Gritta; Federal Biological Research Centre for Agriculture and Forestry, Messeweg 11/12, D- 38104, Braunschweig, Germany
Plant-based agricultural products, like citrus peel oils, are increasingly used as sustainable alternatives to synthetic pesticides. However, in crops such as hop ( Humulus lupulus L.), where viroid infections can seriously reduce yields, there is concern that products made from infected citrus might transmit viroids, especially citrus bark cracking viroid (CBCVd). This study evaluates the risk of viroid transmission by examining CBCVd, hop stunt viroid (HSVd), and citrus exocortis viroid (CEVd) through orange oil using RNA extraction and RT-qPCR analysis. Two extraction methods were tested, with the chaotropic protocol outperforming the detergent-based approach for isolating RNA from oil matrices. Spiking experiments confirmed consistent detection of CBCVd and the plant RNA marker NAD in mixtures containing 90% RNA and 10% oil, even after seven days, indicating RNA stability in oil-rich environments. In contrast, pure oil samples showed no viroid RNA or NAD detection, suggesting limited RNA persistence in pure oil. Of 32 citrus peel samples tested, CBCVd was detected in one and HSVd in seven, but no viroid RNA or NAD was detected in the corresponding oils. These findings indicate a minimal risk of viroid transmission through orange oil; however, formulations containing surfactants or water may allow RNA to partition into aqueous phases, potentially increasing the risk. This study highlights the need for routine testing of raw materials and final citrus-based products to ensure phytosanitary safety.
Impact of different growing substrates on growth, yield and cannabinoid content of two Cannabis sativa L. genotypes in a pot culture
(2020) Burgel, Lisa; Hartung, Jens; Graeff-Hönninger, Simone
The impacts of different growing substrate compositions, consisting of peat (PM), peat substituted with 30% green fibre (G30) and coco coir fibre (CC) growth media, were investigated in regard to the plant height, biomass and floral yield, biomass nitrogen (N) content, root growth, and cannabidiol content (CBD/A) of two phytocannabinoid-rich cannabis genotypes in an indoor pot cultivation system. Genotypes and substrate treatment combinations were randomly allocated to 36 plants according to a Latin square design. The results showed a higher total plant height for PM (39.96 cm), followed by G30 (35.28 cm), and the lowest in CC (31.54 cm). The N content of leaves indicated the highest values for plants grown in G30 (52.24 g kg DW−1), followed by PM (46.75 g kg DW−1) and a significantly lower content for CC (37.00 g kg DW−1). Root length density (RLD) increased by 40% (PM) and 50% (G30), compared to CC treatments, with no significant differences in root dry weight. Both genotypes, Kanada (KAN) and 0.2x, reacted in a genotype-specific manner. KAN indicated a reduced floral yield of plants grown in G30 (4.94 g plant−1) and CC (3.84 g plant−1) compared to PM (8.56 g plant−1). 0.2x indicated stable high floral yields of 9.19 g plant−1 (G30) to 7.90 g plant−1 (CC). Leaf DW increased in PM (5.78 g plant−1) and G30 (5.66 g plant−1) compared to CC (3.30 g plant−1), while CBD/A content remained constant. Due to a higher biomass yield, the CBD/A yield of flowers (549.66 mg plant−1) and leaves (224.16 mg plant−1) revealed 0.2x as an interesting genotype for indoor pot cultivation in a peat-based substrate substituted with 30% green fibres. Overall, the demand for organic green fibres to partly replace fractionated peat showed a genotype-specific option for a homogeneous plant development, with comparable high biomass yields and stable cannabinoid contents compared to a peat containing standard substrate.
Impact of soil improvers on soil health: A data mining approach to support sustainable agriculture across the EU
(2025) Nolfi, Lorenzo; Bindo, Arianna; Di Gregorio, Luciana; Costanzo, Manuela; Caldara, Marina; Tabacchioni, Silvia; Visca, Andrea; Salo, Tapio; Bauerle, Andrea; Hansen, Veronika; Bernini, Roberta; Varese, Giovanna Cristina; Manikas, Ioannis; Marmiroli, Nelson; Palojärvi, Ansa; Bevivino, Annamaria
Soil health is crucial for the sustainability of agricultural practices and ecosystem resilience. Using a data mining approach, this study aims to explore emerging themes related to the impact of soil improvers on soil health by analyzing results from various EU-funded agricultural projects, with the final goal of identifying the key factors driving the effectiveness of soil amendments. By integrating data mining and text analysis, the study extracts, aggregates, and visualizes insights, providing a comprehensive overview of innovative strategies to enhance soil fertility and promote ecological balance. This integrated analytical framework offers a nuanced understanding of the conceptual landscape surrounding soil health in EU projects, highlighting the multifaceted roles of organic amendments and microbial solutions. Our findings underscore the critical link between organic amendments and soil health, highlighting their potential as strategic tools for achieving more sustainable agricultural systems. These findings provide a basis for refining soil management strategies in agriculture and support the development of evidence-based policies aimed at improving soil health and fostering ecological balance across Europe.
Improving cover crop mixtures to increase soil carbon inputs and weed suppression as a tool to promote yield potential
(2024) Groß, Jonas; Müller, Torsten
Arable cropping systems are facing challenges imposed by climate change and are, at the same time, a tool to mitigate climate change. Soils are essential in securing yield potential and acting as a carbon sink. Recognizing small-scale site-specific differences in crop management and integrating cover crops, which provide ecosystem services such as carbon sequestration and weed suppression, are two approaches to climate-smart agriculture. To investigate site-specific soil heterogeneity, soil properties were analyzed in a field trial, measuring at three soil depths in 42 plots to determine their influence on yield measures. Soil organic carbon, silt, and clay contents in both topsoil and subsoil explained 45-46% of the variability in grain yield. Additionally, a positive correlation was found between increasing clay content in the topsoil and grain yield and tiller density. A higher clay content in the subsoil resulted in a decrease in grain yield. Soil organic carbon was identified as a soil property that positively influences yield and yield formation at any soil depth through multiple regressions and cluster analysis. Soil organic carbon is a critical soil measure that can significantly improve yield potential and can be manipulated by crop management practices like cover cropping. In a second field experiment, the impacts of increasing plant diversity of cover crop mixtures on rhizosphere carbon input and microbial utilization were investigated. A comparison was made between Mustard (Sinapis alba L.) planted as a sole crop and diversified cover crop mixtures of four (Mix4) or twelve (Mix12) species. A 13C-pulse labeling field experiment traced C transfer from shoots to roots to the soil microbial community. Mix 4 doubled the net CO2-C removal from the atmosphere, while Mix 12 more than tripled it, indicating that plant diversity positively impacts carbon cycling. This is reflected in higher atmospheric C uptake, higher transport rates to the rhizosphere, higher microbial incorporation, and longer residence time in the soil environment, improving the efficiency of C cycling in cropping systems. Root C-transfer could be identified as a fast pathway for C to reach soil C-compartments, but a substantial share of atmospheric C-catch comes from shoot biomass. In a third field experiment, the influence of species combination on shoot biomass formation was systematically assessed by investigating species interactions in dual cover crop mixtures and their competitiveness to suppress weeds before winter under different growing conditions. The shoot biomass share of a cover crop species in a dual-species mixture was found to be directly linked to its shoot biomass in a pure stand. Mustard and phacelia had similar effects on the shoot biomass production of the second species added to the mixture. Cruciferous species were more competitive against weeds than other cover crop species and could suppress weeds even when mixed with a less competitive partner. Weed suppression in mixtures with phacelia depended on the second component. Our results indicate that dual mixtures containing one competitive species reduce weed shoot biomass before winter, comparable to competitive pure stands. The research in this thesis shows that C content in the soil plays a crucial role in yield formation in arable cropping systems in Germany. Finally, the study has demonstrated that implementing cover crop mixtures can enhance soil C input and represent a valuable method for preserving yield potential. It was also shown that an intelligent combination of cover crop species can determine successful development and weed suppression.
Physico-chemical properties of maize (Zea mays L.) mucilage differ with the collection system and corresponding root type and developmental stage of the plant
(2022) Werner, Lena M.; Knott, Matthilde; Diehl, Doerte; Ahmed, Mutez A.; Banfield, Callum; Dippold, Michi; Vetterlein, Doris; Wimmer, Monika A.
Purpose: Mucilage plays crucial roles in root-soil interactions. Collection systems for maize (Zea mays L.) use primary and seminal roots of aeroponically-grown seedlings (CSA), or brace roots of soil-grown plants (CSB). While each method represents specific plant developmental stages, and root types growing in specific (micro-)environments, these factors are rarely considered. It is unclear whether mucilage exhibits distinct physico-chemical properties related to collection system-inherent factors. Methods: Mucilage of maize genotype B73 was collected from systems CSA and CSB. Chemical composition was assessed by pH, nutrient contents, neutral sugar composition, and polysaccharide polymer length. Viscosity, surface tension and contact angle represented physical properties. Results: The share of hexoses among total polysaccharides was 11% higher in CSB than in CSA, whereas pentoses were predominant in CSA, together with higher nutrient concentrations and pH values. Mannose was detected only in CSB, which also exhibited higher surface tension, viscosity and contact angle compared to CSA. Conclusions: Physico-chemical differences between the two mucilages are related to root type functions, environmental root growth conditions, and plant developmental state. Higher fractions of pentoses in CSA mucilage seem related to semi-sterile system conditions. Higher viscosity of CSB mucilage might reflect the need for enhanced water holding capacity of brace roots growing in drier conditions. A strong influence of environmental factors on mucilage properties even for a single genotype might play additional roles e.g. in the attraction of microbiomes. These aspects are relevant when assessing the role of mucilage in the rhizosphere, or when developing models of rhizosphere processes.
Rhizosphere manipulation to optimize fertilizer and soil phosphate availability
(2024) Herrmann, Michelle Natalie; Müller, Torsten
Phosphorus (P), which occurs as orthophosphate in living organisms, in soil, and in fertilizers, primarily derives from non-renewable resources. Due to open nutrient cycles, most applied P is at risk of ending up in the environment. At the same time, P fertilization in modern agricul-tural systems is inefficient. In Europe, farmers tended to apply more P than the crop’s demand because of P immobilization in soil and the resulting poor fertilizer efficiency. This has led to an accumulation of P in the soil, and environmental P pollution from leaching, soil erosion, and runoff. This work aimed to increase soil P availability and promote the use of recycled P ferti-lizers by improving the P fertilizer use efficiency. The approach compromised various strategies, which shall be evaluated based on their effectiveness in promoting plant growth and P acquisi-tion under P limitation and stimulating P turnover processes close to the rhizosphere. The first study addressed the impact of placed starter fertilization on yield, N and P uptake as well as on nutrient use efficiency. In the last decades, numerous studies have been published, enabling us to summarize the results. Therefore, the positive effect of placed starter fertilization was evaluated by conducting a network meta-analysis. Additionally, one aim was to identify relevant environmental and management factors influencing the effectiveness under field conditions. Here, it was found that placed starter fertilization increased yield by 9.4 %. P uptake and P use efficiency benefitted significantly from a placed starter fertilization, whereas N uptake and N use efficiency were unaffected. The climate was identified as one of the most decisive environmental factors, with arid climates and hyper-humid climates showing the greatest yield advantage. Using ammonium-based fertilizers enhanced the positive effect on yield and P use efficiency. In the second study, biostimulants, as potential enhancers of P availability in soil, were tested for their impact on P turnover in soil, and their ability to improve the fertilizer use efficiency of recycled fertilizers. To distinguish between the influence of biostimulants on soil and the plant-biostimulant interaction, an incubation and a pot trial with maize were designed. Non-microbial and microbial biostimulants were applied to the soil in combination with two recycled P fertilizers. This study revealed that biostimulants did not stimulate P turnover processes with phosphatase activity or microbial biomass P as indicators and only minorly influenced CAL-P in the incubation trial. Likewise, the biostimulants did not affect plant growth and nutrient acquisition in the pot trial. In summary, albeit being a promising strategy to improve P fertilizer utilization, biostimulants were proved again to be unreliable. Two studies focused on integrating legumes in maize-based cropping systems to optimize the use of P stored in the rooting zone and derived from poorly available (recycled) fertilizers. Legume-based crop rotations and legume-maize intercropping systems were tested in pot trials. Key P mobilization processes as well as plant performance and P uptake were studied as indicators for the P use. Legumes consistently stimulated soil P turnover processes independent of the fertilization regime indicated by a higher phosphatase activity and higher Mn-leaf concentration which correlated with the root exudation of carboxylates. Nevertheless, maize did not benefit from integrating legumes into the cropping system. In the crop rotation, maize following a legume did not increase biomass and P offtake compared to maize after maize. With the rel-atively lower biomass production of the legume pre-crop compared to the maize pre-crop, these crop rotations could not keep up with the maize-maize rotation in terms of total biomass pro-duction and P offtake. Concerning the intercropping, maize intercropped with beans was hin-dered in growing due to the competition for limited resources. However, the total biomass pro-duction of the maize–bean intercropping system was significantly higher than the maize monoculture and could compete with the conventional maize monoculture fertilized with triple super phosphate. In summary, this work provides a comprehensive overview and evaluation of future possibili-ties for improving P use efficiency. In combination with recycled fertilizers, intercropping legumes, and a placed starter fertilization can contribute to sustainable P management in the future.
The role of digital technologies to support sustainability management in agriculture
(2025) Weber, Rolf; Lewandowski, Iris
Agriculture causes many environmental problems in the production of food. In addition to the emissions that the agricultural sector emits in the upstream and downstream value chains, the use of plant protection products to increase yields also contributes to the decline in biodiversity. Consumer demands for more sustainable food production are increasing and stricter regulations are also being implemented politically to increase sustainability in European and German agriculture. To achieve this goal, many different assessment tools have been developed to measure and evaluate sustainability in agriculture. In addition to its role in the respective tools, digitization is also becoming increasingly important in food production. The possibilities of digital technologies in agriculture are multifaceted and can help to support farmers in managing their farms. Furthermore, digitization will also have an important impact on sustainability management. Digitization can help to increase the output:input ratio of farm inputs. Improving the efficiency of resource use has an impact on sustainability. However, tools for assessing sustainability in agriculture cannot show whether the use of digital technologies creates synergies or trade-offs. The sustainability tools also have limitations when it comes to assessing biodiversity, as the assessment takes place retrospectively on the one hand and across farms on the other. An algorithm that supports farmers in the field-specific biodiversity assessment before the cultivation season is still missing. Whether farmers are willing to accept the use of digital technologies to support decision-making has not yet been researched. Without the willingness of farmers to invest in digital technologies, the associated efficiency gains will remain unused and thus slow down the development towards a more sustainable agriculture. The aim of this work is to show how sustainability management in agriculture can be improved in food production with the support of digital technologies. In the study, field trials on site-specific fertilization were carried out over a period of four years on three different farms in a case study. Using the example of site-specific fertilization as a digital technology, the on-farm-research trials show which trade-offs and synergies occur between ecological and economic sustainability indicators in the digitization of agriculture in arable farming. Site-specific fertilization has led to an increase in yields, regardless of the size of the farm. This results in lower emissions per unit of product produced. In terms of economic benefits, the results show that farm size is crucial for the profitability of site-specific fertilization. The smaller the size of the farm, the higher the costs per unit associated with the technology. Whether synergies or trade-offs occur between ecological and economic sustainability indicators in site-specific fertilization has to be calculated manually so far, as the sustainability assessment tools do not provide this information. In the second study, an algorithm was developed that assesses the biodiversity potential in an indicator-based and prospective manner. To this end, agricultural management parameters (on-crop) and landscape parameters (off-crop) were first derived from the literature and then discussed in expert interviews. In these interviews, points were awarded for the on-crop and off-crop parameters and parameters influencing biodiversity in particular were weighted twice. The algorithm developed enables the biodiversity potential to be assessed on a field-specific basis. This allows farmers to determine which biodiversity potential is achieved at the cultivation planning stage. In addition, the algorithm can show farmers scenarios on how to optimize biodiversity performance. The third study addresses the social acceptance of digital technologies among farmers. The first and second study showed how the use of digital technologies can support farmers in their management. Therefore, the third research question investigated whether farmers use them at all. A qualitative Delphi study with experts was conducted to find out whether farmers accept and use digital technologies and how they affect the social dimension of sustainability. In most questions, the experts were unsure about farmers' acceptance of digital technologies and the general impact of digitization on farm life. The experts were concerned about data security, dependence on individual providers and the risk of smaller farmers not digitizing and thus being left behind in the digitization process because the costs of the technology are too high. Digital technologies can support the farmer's management on the one hand and contribute to a standardized sustainability assessment by automatically evaluating existing data on the other. However, this requires better interoperability of different software programs so that all data generated on the farm can be collected and evaluated centrally. This can enable the automation of the sustainability assessment and the transparency of sustainability performance for the downstream value chain. However, dealing with trade-offs within the sustainability dimensions when using digital technologies on the one hand, and the risk that farmers will not digitize due to a lack of economic viability on the other, hinder the digitization process.
Root foraging strategy improves the adaptability of tea plants (Camellia sinensis L.) to soil potassium heterogeneity
(2022) Ruan, Li; Cheng, Hao; Ludewig, Uwe; Li, Jianwu; Chang, Scott X.
Root foraging enables plants to obtain more soil nutrients in a constantly changing nutrient environment. Little is known about the adaptation mechanism of adventitious roots of plants dominated by asexual reproduction (such as tea plants) to soil potassium heterogeneity. We investigated root foraging strategies for K by two tea plants (low-K tolerant genotype “1511” and low-K intolerant genotype “1601”) using a multi-layer split-root system. Root exudates, root architecture and transcriptional responses to K heterogeneity were analyzed by HPLC, WinRHIZO and RNA-seq. With the higher leaf K concentrations and K biological utilization indexes, “1511” acclimated to K heterogeneity better than “1601”. For “1511”, maximum total root length and fine root length proportion appeared on the K-enriched side; the solubilization of soil K reached the maximum on the low-K side, which was consistent with the amount of organic acids released through root exudation. The cellulose decomposition genes that were abundant on the K-enriched side may have promoted root proliferation for “1511”. This did not happen in “1601”. The low-K tolerant tea genotype “1511” was better at acclimating to K heterogeneity, which was due to a smart root foraging strategy: more roots (especially fine roots) were developed in the K-enriched side; more organic acids were secreted in the low-K side to activate soil K and the root proliferation in the K-enriched side might be due to cellulose decomposition. The present research provides a practical basis for a better understanding of the adaptation strategies of clonal woody plants to soil nutrient availability.
Sheltered by trees: long-term yield dynamics in temperate alley cropping agroforestry with changing water availability
(2025) Koch, Olef; Moore, Jennifer; Hörl, Jakob; Cormann, Michael; Gayler, Sebastian; Lewandowski, Iris; Marhan, Sven; Munz, Sebastian; Pflugfelder, Markus; Piepho, Hans-Peter; Schneider, Julia; von Cossel, Moritz; Weinand, Tanja; Winkler, Bastian; Schweiger, Andreas H.
As warm season droughts increase in frequency due to climate change, causing severe yield losses especially among cereal crops, European agriculture is in dire need of adaptation. While agroforestry is widely regarded as a key adaptation measure, little is known on how yield performance is influenced by changing water availability in temperate regions. Therefore, we assessed the yield dynamics of five winter crops (winter wheat, triticale, winter barley, winter pea, and rapeseed) during seven growing seasons (2012 to 2023) in a well-established (since 2007) alley cropping agroforestry trial site in Southwestern Germany. The trial integrated three different agroforestry practices in a randomized block design: (i) willow short-rotation coppice, (ii) walnut trees for nut production, and (iii) diverse hedgerows. The relationship between crop yield and climatic water balance was analyzed using a linear mixed-model. In this unique long-term comparison, we demonstrate that individual alley cropping practices exhibited distinct yield patterns with increased distance to tree rows. In contrast to the willow short rotation coppice, walnut and hedgerows did not evoke significant winter crop yield declines at proximity. While in the walnut plots yields did not significantly vary with distance to tree rows, yields adjacent to hedge rows declined significantly towards the alley center. Moreover, tree rows contributed to stable crop yields under fluctuating water availability in their proximity and up to the alley center on their leeward side while yields significantly varied with changing climatic water balance on the windward side. Our results underline the potential of agroforestry to sustain yields in the face of increasingly variable water availability, further substantiating the contribution of alley cropping agroforestry for farming systems’ resilience to increasingly variable weather conditions. They moreover contribute to planning and policy support for advancing agroforestry as a climate smart solution in temperate regions.
Spotlight on agroecological cropping practices to improve the resilience of farming systems: a qualitative review of meta-analytic studies
(2025) von Cossel, Moritz; Scordia, Danilo; Altieri, Miguel; Gresta, Fabio
The capacity of agriculture to withstand or recover from increasing stresses (i.e., resilience) will be continuously challenged by extreme climate change events in the coming decades, altering the growing conditions for crop species. By prioritizing natural processes, agroecology seeks to foster climate change adaptation, boost resilience, and contribute to a low-emission agricultural system. Nineteen different agroecological practices using resilience-related terms and “meta-analysis”, within the subject areas ‘Agriculture and Biological Science’ and ‘Environmental Science’ were addressed, and 34 meta-analyses were reviewed to summarize the state-of-the-art agroecological adaptative strategies applied globally, and the current knowledge gaps on the role of agroecological practices in improving farming system resilience. Two main agroecological strategies stand out: i) crop diversification and ii) ecological soil management. The most frequent diversification practices included agroforestry, intercropping, cover cropping, crop rotation, mixed cropping, mixed farming, and the use of local varieties. Soil management practices included green manure, no-till farming, mulching, and the addition of organic matter. The analyzed studies highlight the complex interplay among soil, plant, climate, management, and socio-economic contexts within the selected agroecological practices. The results varied—positive, null, or negative—depending largely on site-specific factors. Developing and understanding more complex systems in a holistic approach, that integrates plants and animals across multiple trophic levels (feeding relationships, nutrient cycling, and aligning with the principles of a circular economy) is essential. More research is, therefore, needed to understand the interactions between crop diversity and soil management, their impacts on resilience, and how to translate research into practical strategies that farmers can implement effectively.
Status quo of fertilization strategies and nutrient farm gate budgets on stockless organic vegetable farms in Germany
(2024) Stein, Sophie; Hartung, Jens; Zikeli, Sabine; Möller, Kurt; Reents, Hans Jürgen
Fertilizer management in stockless organic vegetable production is strongly affected by external nutrient purchases due to the high nitrogen (N) and potassium (K) requirements of vegetables. However, the database on nutrient flows and budgets in organic vegetable farming in Europe is very limited. Therefore, a survey based on semi-structured interviews was carried out comprising 12 organic horticultural farms in Germany. The results show that three different main fertilizer categories are used as inputs in different ratios by the inventoried farms: (1) base fertilizers (e.g., composts, solid farmyard manures), (2) commercial organic N fertilizers (e.g., keratins or plant products from food production or fermentation processes), and (3) commercial mineral fertilizers (e.g., potassium sulfate), all of which are approved for organic production. Ninety percent of the total nutrient inputs to the farms came from these fertilizers and biological N2 fixation, with the remaining 10% coming from other inputs, such as seeds or growing media. The estimated yearly average total farm budgets were nearly balanced across all farms with moderate surpluses (67.5 kg N ha−1, 2.06 kg P ha−1, and 0.26 kg K ha−1). However, large imbalances were found for most of the individual farms. These imbalances indicate the risk of nutrient accumulation or nutrient depletion in the soil, depending on the fertilization strategy and productivity of the farm. More specifically, increasing N share from base fertilizers led to increased P and K budgets, while strategies based on the use of large amounts of keratins led to the opposite—K and P depletion. We concluded that balanced nutrient management in organic vegetable production systems requires a thorough calculation and should combine the use of base fertilizers, commercial fertilizers with low P content, and increased N supply via BNF.
Testing agronomic treatments to improve the establishment of novel miscanthus hybrids on marginal land
(2025) Lewin, Eva; Clifton‐Brown, John; Jensen, Elaine; Lewandowski, Iris; Krzyżak, Jacek; Pogrzeba, Marta; Hartung, Jens; Wolfmüller, Cedric; Kiesel, Andreas; Fujii, Yoshiharu
Miscanthus is considered a promising candidate for the cultivation of marginal land. This land poses unique challenges, and experiments have shown that the “establishment phase” is of paramount importance to the long-term yield performance of miscanthus. This experiment analyzes novel miscanthus hybrids and how their establishment on marginal land can be improved through agronomic interventions. Experiments took place at two sites in Germany: at Ihinger Hof, with a very shallow soil profile and high stone content, and at Reichwalde, where the soil was repurposed river sediment with low organic matter, high stone content, and a compacted lower horizon. These marginal conditions functioned as test cases for the improvement of miscanthus establishment agronomy. Four hybrids ( Miscanthus x giganteus , Gnt10, Gnt43, and Syn55) and agronomic treatments such as plastic mulch film, miscanthus mulch, inoculation with mycorrhizal fungi, and fertilization were tested in two years at both sites in 2021 and 2022. Specific weather conditions and the timing of planting were strong determinants of establishment success and no single treatment combination was found that consistently increased the establishment success. Plastic mulch films were found to hinder rather than help establishment in both these locations. Chipped miscanthus mulch caused nitrogen immobilization and stunted plant growth. At Ihinger Hof the novel seed-based miscanthus hybrid Gnt43 produced twice the biomass of other hybrids (7 t ha −1 ) in the first growing season. Gnt10 yielded well in 2021 and showed impressive tolerance to water stress in the summer of 2022. No treatment combination was found that consistently increased the establishment success of miscanthus hybrids across sites and years. Novel genotypes consistently outperformed the standard commercial miscanthus hybrid Miscanthus x giganteus . Gnt10 may be a promising candidate for the cultivation of water-stress-prone marginal lands, due to its isohydric behavior and high yield potential.

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