Soil Science and Plant Nutrition

Head of Department and Laboratory: Prof. Dr Florian Wichern · Tel. (02821) 806 73-234 · florian.wichern(at)hochschule-rhein-waal.de

Research and technical staff:

• Dr Conor Watson – Soil Science and Environmental Chemistry
• Julia Gorris – Crop Production and Plant Health
• Dr Lia Moreno Codinachs – Analytical Science and Analytical Chemistry
• Michael Hemkemeyer – Soil Microbiology
• Christoph Knoblauch – Trace gases, nutrient fluxes and modelling
• Bernou van der Wiel – Regional material flow analyses
• Sanja Schwalb – Stoichiometry of microbial communities in soil
• Bernd Hetjens – Endophytes in potatoes
• Zhyldyz Oskonbaeva – Influence of environmental factors on walnut quality
• Charlotte Schlösser – Cover crop project, endophytes in potatoes
• Rita Theelen – Intercropping project
• Rüdiger Schmidt – Lecturer in Sustainability Studies and Organic Farming
• Franz-Josef Kuhnigk – Master Gardener (greenhouse)

Student and research assistants: Sabrina Meisen, Malte Oetker, Osuri Ratnayake, Blanca Paschen, Jakob Vögerl, Lennart Jansen, Rusan He, Gonne Clasen, Benedikt Meier, Katharina Coort, Shiwei Li, Maurice Stümpel, Bastian Hetzer.

The research group has a wide range of methods and equipment at its disposal to investigate the interactions between plant roots, the soil and soil microorganisms. Experiments are carried out over various time scales (ranging from hours to years) and spatial scales – as field and laboratory trials (including in collaboration with the North Rhine-Westphalia Chamber of Agriculture), pot experiments in tropical greenhouses, climate chambers and growth cabinets, as well as in incubation cabinets.

Field and pot experiments

• Weather station
• Penetrologger (soil penetration resistance)
• Photoacoustic trace gas analyser (INNOVA) for CO₂, N₂O, CH₄ and NH₃ emissions
• Infrared gas analyser (LICOR) for photosynthetic activity and soil respiration

Plant-level analyses

• Dry matter and ash content of above- and below-ground biomass
• Nutrient and metal content (ICP-OES, Perkin Elmer)
• Photosynthesis analyser (LICOR), chlorophyll analyser (SPAD), leaf area analyser
• Root washing system and root scanner (WinRHIZO)
• Light microscope and binocular microscope
• Arbuscular mycorrhiza (staining), secondary plant metabolites (HPLC-MS)

Soil physics and soil chemistry

• Aggregate stability, bulk density, penetration resistance
• DOC/TNb determination (Analytik Jena)
• Continuous-flow autoanalyser (SEAL) for nitrate, ammonium and phosphate
• ICP-OES (Perkin Elmer) for total nutrient and heavy metal content
• Digestion unit, two photometers, multi-plate reader, four automatic titrators
• HPLC (ergosterol measurement), pH, redox potential, carbonate content, cation exchange capacity

Soil biology

• Microbial activity (soil respiration, enzyme activity, trace gases)
• Microbial biomass (chloroform fumigation extraction, SIR, qPCR)
• Microbial community structure: ergosterol (HPLC), fungi/bacteria/archaea (qPCR)
• C/N transfer from the plant to the soil via labelling with stable isotopes (¹³C, ¹⁵N)

A selection of the research group’s externally funded research projects (you can find further projects in the project list on the Research Overview page):

• BASS – technical and scientific evaluation of a new lime-sulphur fertiliser.
• EffiZwisch – Efficient catch-crop cultivation for improved climate, water and soil protection (MULNV, 2015–2018)
• SPECTORS – Sensor Products for Enterprises Creating Technological Opportunities in Remote Sensing (INTERREG Va, 2016–2020)
• Soil ionoMICS – Elemental composition of soil microorganisms as an indicator of soil fertility and soil carbon and nitrogen sequestration (MKW, 2017–2020)
• SusWalFood – Value creation and sustainable use of underutilised plant species in Kyrgyzstan’s walnut forests (BMBF, 2017–2019)
• optiGRASS – Integrated model for predicting nitrogen requirements in intensively managed grassland (MULNV, 2018–2019)
• Food Pro.tec.ts – Food production technologies for cross-border systems (INTERREG Va, 2016–2020)

Publications by the research group in peer-reviewed journals:

• Smanalieva J, Iskakova J, Oskonbaeva Z, Wichern F, Darr D (2020): Investigation of nutritional characteristics and free radical scavenging activity of wild apple, pear, rosehip and barberry from the walnut-fruit forests of Kyrgyzstan. European Food Research and Technology.
• Wichern F, Islam MdR, Hemkemeyer M, Watson C (2020): Organic amendments alleviate the effects of salinity on soil microorganisms and mineralisation processes in aerobic and anaerobic paddy rice soils. Frontiers in Sustainable Food Systems 4:30.
• Watson C, Clemens J, Wichern F (2020): Hazenite: a new secondary phosphorus, potassium and magnesium fertiliser. Plant, Soil and Environment 66: 1–6.
• Schages L, Wichern F, Kalscheuer R, Bockmühl D (2020): Winter is coming – Impact of temperature on the variation of beta-lactamase and mcr genes in a wastewater treatment plant. Science of the Total Environment 712, 136499.
• van der Wiel BZ, Weijma J, van Middelaar CE, Kleinke M, Buisman CJN, Wichern F (2019): A review of nutrient stock and flow analyses of agro-food-waste systems in local areas. Resources, Conservation and Recycling X 3, 100014.
• Smanalieva J, Iskakova J, Oskonbaeva Z, Wichern F, Darr D (2019): Determination of physicochemical parameters, phenolic content, and antioxidant capacity of wild cherry plum (Prunus divaricata) from the walnut-fruit forests of Kyrgyzstan. European Food Research and Technology 245: 2293–2301.
• Hupe A, Schulz H, Bruns C, Haase T, Heß J, Dyckmans J, Joergensen RG, Wichern F (2019): Get on your boots: Estimating root biomass and rhizodeposition of peas under field conditions. Plant and Soil 443: 449–462.
• Watson C, Clemens J, Wichern F (2019): Plant availability of Mg and P from struvite with concurrent application of a nitrification inhibitor. Soil Use and Management 35: 675–682.
• in 't Zandt D, Fritz C, Wichern F (2018): In the land of plenty: Catch crops trigger nitrogen uptake by soil microorganisms. Plant and Soil 423: 549–562.
• Joergensen RG, Wichern F (2018): Alive and kicking: Why dormant soil microorganisms matter (Review). Soil Biology and Biochemistry 116: 419–430.
• Knoblauch C, Watson C, Becker R, Berendonk C, Wrage-Mönnig N, Wichern F (2017): Relationship between remote sensing data, plant biomass and soil nitrogen dynamics in intensively managed grassland. Sensors 17(7).
• Vihotogbé R, Kakai G, Watson C, Wichern F, Sinsin B, Gebauer J (2017): Effects of salinity on seedling emergence and early seedling growth of Irvingia gabonensis. Seed Science and Technology 45(2): 1–14.
• Kanders MJ, Berendonk C, Fritz C, Watson C, Wichern F (2017): Catch crops store more nitrogen below ground when rhizodeposits are taken into account. Plant and Soil 417: 287–299.
• Watson C, Bahadur K, Brieß L, Dußling R, Kohler F, Weinsheimer S, Wichern F (2017): Mitigating negative microbial effects of p-nitrophenol, phenol, copper and cadmium in a sandy loam soil using biochar. Water, Air and Soil Pollution 228: 74–84.
• Knoblauch C, Watson C, Becker R, Berendonk C, Wichern F (2017): Changes in ergosterol content following the application of inorganic N fertiliser do not affect short-term C and N mineralisation patterns in a grassland soil. Applied Soil Ecology 111: 57–64.
• Iqbal T, Joergensen RG, Knoblauch C, Lucassen R, Singh Y, Watson C, Wichern F (2016): The addition of rice straw does not substantially alter microbial properties under hypersaline soil conditions. Biology and Fertility of Soils 52: 867–877.
• Watson C, Singh Y, Iqbal T, Knoblauch C, Simon P, Wichern F (2016): Short-term effects of polyacrylamide and dicyandiamide on C and N mineralisation in a sandy loam soil. Soil Use and Management 32: 127–136.
• Gebauer J, Adam YO, Ahmed MFEM, Sanchez AC, Darr D et al., Wichern F, Wiehle M, Kehlenbeck K (2016): Africa’s wooden elephant: the baobab tree (Adansonia digitata L.) in Sudan and Kenya – a review. Genetic Resources and Crop Evolution 63: 377–399.
• Hupe A, Schulz H, Joergensen RG, Bruns C, Wichern F (2016): Digging in the dirt – Inadequacy of belowground plant biomass quantification. Soil Biology and Biochemistry 96: 137–144.
• Eck T, Potthoff M, Dyckmans J, Wichern F, Joergensen RG (2015): Priming effects of Aporrectodea caliginosa on young rhizodeposits and old soil organic matter following the addition of wheat straw. European Journal of Soil Biology 70: 38–45.
• Gebauer J, Assem A, Busch E, Hardtmann S, Möckel D, Krebs F, Ziegler T, Wichern F, Wiehle M, Kehlenbeck K (2014): The baobab (Adansonia digitata L.): Wild fruit from Africa for Germany and Europe?! Commercial Fruit Growing 56: 9–24.
• Zareitalabad P, Siemens J, Wichern F, Amelung W, Joergensen RG (2013): Dose-dependent reaction of Aporrectodea caliginosa to perfluorooctanoic acid and perfluorooctanesulfonic acid in soil. Ecotoxicology and Environmental Safety 95: 39–43.
• Khan KS, Castillo X, Wichern F, Dyckmans J, Joergensen RG (2012): Interactions between mustard plants and soil microorganisms following the application of sugarcane filter cake and pea residues to an Andosol. Journal of Plant Nutrition and Soil Science 175: 931–938.
• Wichern F, Andreeva D, Joergensen RG, Kuzyakov Y (2011): Stem labelling results in different patterns of 14C rhizorespiration and 15N distribution in plants compared to natural assimilation pathways. Journal of Plant Nutrition and Soil Science 174: 732–741.
• Wichern F, Mayer J, Joergensen RG, Müller T (2010): Evaluation of the wick method for in situ 13C and 15N labelling of annual plants using sugar-urea mixtures. Plant and Soil 329: 105–115.
• Wichern F, Joergensen RG (2009): Soil microbial properties along a precipitation transect in southern Africa. Arid Land Research and Management 23: 115–126.
• Mueller E, Wildhagen H, Heß J, Wichern F, Joergensen RG (2009): Spatial patterns of soil biological and physical properties in a ridge-tilled and a ploughed Luvisol. Soil and Tillage Research 105: 88–95.
• Mueller E, Wildhagen H, Heß J, Wichern F, Joergensen RG (2009): CO₂ evolution from a ridge-tilled and a mouldboard-ploughed Luvisol in the field. Applied Soil Ecology 43: 89–94.
• Wichern F, Eberhardt E, Mayer J, Joergensen RG, Müller T (2008): Nitrogen rhizodeposition in agricultural crops: Methods, estimates and future prospects (Review). Soil Biology and Biochemistry 40: 30–48.
• Joergensen RG, Wichern F (2008): Quantitative assessment of the fungal contribution to microbial biomass in soil (Review). Soil Biology and Biochemistry 40: 2977–2991.
• Luedeling E, Wichern F (2007): The need for site-specific adaptation of organic standards: The example of dryland salinity in Australia. Journal of Agriculture and Rural Development in the Tropics and Subtropics, Suppl. 89: 121–142.
• Raubuch M, Roose K, Warnstorff K, Wichern F, Joergensen RG (2007): Respiration patterns and microbial utilisation of field-grown transgenic Bt maize residues. Soil Biology and Biochemistry 39: 2380–2389.
• Wichern F, Mayer J, Joergensen RG, Müller T (2007): Rhizodeposition of C and N in peas and oats following 13C-15N double labelling under field conditions. Soil Biology and Biochemistry 39: 2527–2537.
• Wichern F, Mayer J, Joergensen RG, Müller T (2007): Release of C and N from the roots of peas and oats and their availability to soil microorganisms. Soil Biology and Biochemistry 39: 2829–2839.
• Wichern J, Wichern F, Joergensen RG (2006): Impact of salinity on soil microbial communities and the decomposition of maize in acidic soils. Geoderma 137: 100–108.
• Luedeling E, Nagieb M, Wichern F, Brandt M, Boettcher J, Buerkert A (2005): Drainage, salt leaching and physico-chemical properties of irrigated man-made terrace soils in a mountain oasis in northern Oman. Geoderma 125: 273–285.
• Wichern F, Luedeling E, Müller T, Joergensen RG, Buerkert A (2004): Field measurement of the CO₂ evolution rate under different crops during an irrigation cycle in the mountain oasis of Bald Seet, Oman. Applied Soil Ecology 25: 85–91.
• Wichern F, Müller T, Joergensen RG, Buerkert A (2004): Effects of manure quality and application forms on soil C and N turnover in a subtropical oasis soil under laboratory conditions. Biology and Fertility of Soils 39: 165–171.
• Wichern F, Amelung W, Lobe I, Müller T, Joergensen RG, Buerkert A (2004): Changes in amino acid enantiomers and microbial performance in soils from a subtropical mountain oasis in Oman that had been abandoned for varying periods of time. Biology and Fertility of Soils 39: 398–406.
• Wichern F, Richter C, Joergensen RG (2003): Soil fertility decline at a subtropical South African vertisol site used as a home garden. Biology and Fertility of Soils 37: 288–294.

Further publications, posters and presentations:

• Meisen S, Perl E, Grätz A, Wolk K, Smanalieva J, Oskonbaeva Z, Darr D, Wichern F (2018): Quality parameters of walnut (Juglans regia) fruits from Kyrgyzstan as affected by abiotic properties and intraspecific variability. Tropentag, Ghent.
• Schwalb SA, Hemkemeyer M, Heinze S, Joergensen RG, Wichern F (2018): Soil ionoMICS – Are soil fertility and their C and N storage capacity linked to the elemental composition of microorganisms? ISME 17, Leipzig (poster).
• Schwalb SA, Hemkemeyer M, Heinze S, Joergensen RG, Wichern F (2018): Soil ionoMICS – Linking the elemental composition of microorganisms to soil fertility. Ecology of Soil Microorganisms, Helsinki (poster).
• Schwalb SA, Hemkemeyer M, Heinze S, Joergensen RG, Wichern F (2018): Soil ionoMICS – The importance of the elemental composition of microorganisms for soil fertility. Bonares Conference, Berlin (poster).
• Hupe A, Schulz H, Joergensen RG, Heß J, Wichern F (2017): The significance of various nitrogen transfer pathways in pea-cereal mixtures. Communications of the Society for Crop Science 29: 144–145.
• Caspersen L et al., Gebauer J, Wichern F, Thevs N, Kugler F, Darr D (2017): Utilising the nutritional potential and secondary plant compounds of neglected fruit trees in the walnut-fruit forests of Kyrgyzstan. Tropentag, Bonn (talk).
• Wichern F, Islam MdR, Watson C (2017): Effects of salinity on short-term carbon and nitrogen mineralisation and soil microbial properties in a paddy rice soil. Tropentag, Bonn (poster).
• Watson C, Bahadur K, Brieß L, Dußling R, Kohler F, Weinsheimer S, Wichern F (2017): Mitigating the negative microbial effects of p-nitrophenol, phenol, copper and cadmium using biochar. DBG Annual Meeting, Göttingen (talk).
• Hupe A, Schulz H, Joergensen RG, Heß J, Wichern F (2017): Optimised determination of underground plant biomass in theory and practice. Annual Meeting of the DBG, Göttingen (talk).
• Hemkemeyer M, Bufe C, Fritz C, Wrage-Mönnig N, Wichern F (2017): Cover crops grown in monoculture and mixed cropping affect soils differently. Annual Meeting of the DBG, Göttingen (presentation).
• Fritz C, Geurts J, Weideveld S, Temmink R, Bosma N, Wichern F, Smolders F, Lamers L (2017): To measure is to know in land subsidence mitigation. Bodem 2: 20–22.
• Wichern F, Kanders MJ, Berendonk C, in t Zandt D, Fritz C (2017): Below-ground effects of catch crops. XVIII International Plant Nutrition Colloquium, Copenhagen (poster).
• Hupe A, Näther F, Joergensen RG, Heß J, Bruns C, Wichern F (2017): Where has all the nitrogen gone? – Different transfer pathways from peas to cereals. IPNC, Copenhagen (Poster).
• Hupe A, Schulz H, Joergensen RG, Heß J, Bruns C, Haase T, Wichern F (2017): Improved estimation of below-ground plant biomass. IPNC, Copenhagen (Poster).
• Hemkemeyer M, Berendonk C, Bufe C, Dünnebacke I, Fritz C, Kivelitz H, Wrage-Mönnig N, Wichern F (2017): Potential of cover crop species and mixtures to enhance nutrient supply. IPNC, Copenhagen (Poster).
• Watson C, Clemens J, Wichern F (2017): Plant availability of P and Mg from struvite with concurrent application of a nitrification inhibitor. IPNC, Copenhagen (poster).
• Wichern F (2017): The rhizosphere – How soil life promotes fertility. Strube Wheat Field Day, Söllingen (presentation).
• Kleinke M, Watson C, Wichern F (2017): Food production technologies for transboundary systems – The use of underutilised phosphorus reserves for fertilisation. Humboldt Kolleg, Yaoundé (invited talk).
• Hupe A, Schulz H, Joergensen RG, Heß J, Wichern F (2016): Quantification of C and N rhizodeposition by peas in the field. Communications of the Society for Crop Science 28: 216–217.
• Knoblauch C, Watson C, Becker R, Berendonk C, Wrage-Mönnig N, Wichern F (2016): Nitrogen effects on nitrous oxide emissions in intensively managed permanent grassland. 19th Nitrogen Workshop, Skara (poster).
• Watson C, Singh Y, Iqbal T, Knoblauch C, Simon P, Wichern F (2016): Effects of polyacrylamide and dicyandiamide on carbon and nitrogen mineralisation. 19th Nitrogen Workshop, Skara (poster).
• in t Zandt D, Arico A, Lehnert D, Fritz C, Wichern F (2016): Cover crops trigger nitrogen uptake by soil microorganisms. 19th Nitrogen Workshop, Skara (presentation).
• Potthoff M, Wichern F, Dyckmans J, Joergensen RG (2016): Earthworms and priming of soil organic matter. EGU General Assembly, Vienna (presentation).
• Wichern F, in t Zandt D, Arico A, Lehnert D, Cleven M, Kanders MJ, Berendonk C, Fritz C (2015): Effects of cover crops on soil fertility and nitrogen dynamics. DFG Research Training Group 1397, Witzenhausen (presentation).
• Hupe A, Schulz H, Joergensen RG, Näther F, Haase T, Wichern F (2015): Quantification of C and N rhizodeposition by peas in the field. German Society for Plant Nutrition, Göttingen (presentation).
• Knoblauch C, Watson C, Wrage-Mönnig N, Becker R, Berendonk C, Wichern F (2015): Fertilisation and root presence in permanent grassland have no effect on microbial biomass and mineralisation. Annual Conference of the DBG, Munich (presentation).
• Wichern F, in t Zandt D, Arico A, Lehnert D, Cleven M, Kanders MJ, Berendonk C, Fritz C (2015): Rooting patterns of cover crops and soil microbial properties as affected by nitrogen fertilisation. Annual Meeting of the DBG, Munich (presentation).
• Hupe A, Schulz H, Joergensen RG, Näther F, Haase T, Wichern F (2015): Quantification of C and N rhizodeposition under field conditions. Annual Meeting of the German Botanical Society (DBG), Munich (presentation).
• Fritz C, Visser E, Smolders A, Lamers L, Wichern F, Dullo B, Elzenga T, Pancotta V, Grootjans A (2015): Severe rhizosphere oxygenation optimising the carbon footprint of paludiculture. Rhizosphere 4, Maastricht (poster).
• Fritz C, Visser E, Hinsinger P, Doussan C, de Kroon H, in t Zandt D, Bérard A, Wichern F (2015): Seeking water: Rooting depth and drought tolerance of Zea mays genotypes. Rhizosphere 4, Maastricht (poster).
• Hupe A, Joergensen RG, Haase T, Näther F, Schulz H, Wichern F (2015): Quantification of C and N rhizodeposition of peas under field conditions. Rhizosphere 4, Maastricht (poster).
• Kanders MJ, Berendonk C, Fritz C, Wichern F (2015): Cover crops store more N when considering the total below-ground biomass. Rhizosphere 4, Maastricht (presentation).
• Knoblauch C, Watson C, Wrage-Mönnig N, Becker R, Berendonk C, Wichern F (2015): Fertilisation and root presence in permanent grassland have no effect on microbial biomass and mineralisation. Rhizosphere 4, Maastricht (poster).
• in t Zandt D, Arico A, Lehnert D, Fritz C, Wichern F (2015): The influence of nitrogen fertilisation on rooting patterns and nitrogen recovery of catch crops. Rhizosphere 4, Maastricht (poster).
• Wichern F et al., Watson C (2015): Comparison of soil biological properties between organic and conventional demonstration plots: integrating research into regular teaching modules. Organic Farming Scientific Conference, Eberswalde (poster).
• Hupe A, Näther F, Hans L, Bruns C, Heß J, Joergensen RG, Haase T, Wichern F (2015): Temporal dynamics of pea rhizodeposition. Organic Farming Research Conference, Eberswalde (presentation).
• Wichern F, Singh Y, Iqbal T, Watson C, Knoblauch C, Simon PF (2014): Interactive effects of polyacrylamide and dicyandiamide on soil organic matter and nutrient dynamics. Tropentag (poster).
• Wichern F, Iqbal T, Watson C, Singh Y, Knoblauch C, Joergensen RG (2014): Effects of salinity on soil microbial properties and nutrient fluxes in a rice paddy soil during short-term aerobic incubation. Tropentag (presentation).
• Kanders MJ, Berendonk C, Fritz C, Wichern F (2014): Nitrogen uptake by catch crops: Estimating the below-ground contribution. DGP 2014 (presentation).
• Wichern F (2014): How accurately can we estimate below-ground nitrogen in legumes? 18th Nitrogen Workshop, Lisbon (poster).
• Kanders MJ, Berendonk C, Fritz C, Wichern F (2014): Estimation of below-ground nitrogen in catch crops. 18th Nitrogen Workshop, Lisbon (Poster).
• Wichern F, Singh Y, Iqbal T, Knoblauch C, Watson C, Simon PF (2014): Effects of polyacrylamide and dicyandiamide on carbon and nitrogen mineralisation. 18th Nitrogen Workshop, Lisbon (Poster).
• Knoblauch C, Watson C, Becker R, Berendonk C, Wichern F (2014): Influence of nitrogen fertilisation on carbon and nitrogen mineralisation, microbial biomass and soil respiration in grassland soils. 18th Nitrogen Workshop, Lisbon (poster).
• Näther F, Schmidt A, Hans L, Bruns C, Heß J, Joergensen RG, Haase T, Wichern F (2014): Transfer processes of C and N from peas to cereals. 18th Nitrogen Workshop, Lisbon (presentation).
• Schmidt A, Näther F, Hans L, Bruns C, Heß J, Joergensen RG, Haase T, Wichern F (2014): Temporal dynamics of nitrogen rhizodeposition in peas. 18th Nitrogen Workshop, Lisbon (poster).
• Wichern F (2014): N fixation by catch crops: New insights from the soil. Training for farmers on the EU Water Framework Directive (presentation).
• Potthoff M, Eck T, Wichern F, Dyckmans J, Joergensen RG (2013): Biological utilisation of C and N from rhizodeposition in an incubation study. Annual Conference of the DBG, Rostock (poster).
• Knoblauch C, Watson C, Becker R, Berendonk C, Wichern F (2013): Effects of nitrogen fertilisation on carbon and nitrogen mineralisation from organic matter and roots in grassland soils. Annual Meeting of the DBG, Rostock (presentation).
• Näther F, Schmidt A, Hans L, Heß J, Joergensen RG, Haase T, Wichern F (2013): Processes of C and N transfer between peas and cereals in mixed cropping. Annual Meeting of the DBG, Rostock (presentation).
• Schmidt A, Näther F, Hans L, Heß J, Joergensen RG, Haase T, Wichern F (2013): Effect of mycorrhiza on C and N rhizodeposition in peas. Annual Meeting of the DBG, Rostock (presentation).
• Kanders M, Schmidt R, Darr D, Wichern F (2013): Carbon stocks and local sequestration potential of a forest in North Rhine-Westphalia. Annual Conference of the DBG, Rostock (poster).
• Kanders M, Schmidt R, Darr D, Wichern F (2013): Adapted forest management to combat climate change: The forest as a carbon sink. AFZ-DerWald 6: 11–13.
• Kothes C, Wichern F, Schmidt R, Gebauer J (2013): Self-harvesting projects: A marketing tool for neglected vegetables? Annual Conference of the DGG, Bonn (poster).
• Wichern F (2012): How accurately can we estimate leguminous below-ground nitrogen as an important input in organic cropping systems? DFG Research Training Group 1397, Witzenhausen (poster).
• Wichern F, Joergensen RG (2012): How does soil salinity affect soil microbial communities and related matter fluxes? DFG Research Training Group 1397, Witzenhausen (presentation).
• Mandal S, Spijkers A, Wrage N, Gebauer J, Wichern F (2012): Sustainable development of agriculture in Bangladesh. German Tropical Day (poster).
• Wichern F (2012): The hidden half: Estimating below-ground plant N. Conference: Nitrogen cycling in terrestrial ecosystems, Nanjing, China (presentation).
• Wichern F (2010): Sustainable agriculture: necessity and opportunity. 1st Future Forum on Agribusiness in the Lower Rhine Region, Alpen (presentation).
• Ebert G, Wichern F (2008): Balanced fertilisation – A prerequisite for sustainable improvement of crop yield and quality in developing countries. German Tropical Day (presentation).
• Hülsebusch C, Wichern F, Wolff P, Hemann H (eds.) (2007): Organic agriculture in the tropics and subtropics: Current status and perspectives. Journal of Agriculture and Rural Development in the Tropics and Subtropics, Suppl. 89, 166 pp.
• Wichern F (2007): Estimating C and N rhizodeposition of peas and oats. PhD thesis, Kassel University Press.
• Wichern F, Mayer J, Joergensen RG, Müller T (2007): Quantities and turnover of C and N rhizodeposition in peas and oats under field conditions. Annual Conference of the DBG, Dresden (presentation).
• Wichern F, Mayer J, Joergensen RG, Müller T (2006): In situ 13C–15N dual labelling of peas and oats. Workshop on Stable Isotopes in Soil Science, DBG, Göttingen (presentation).
• Wichern F, Mayer J, Müller T, Joergensen RG (2005): In situ labelling of root biomass and rhizodeposits. Rhizosphere 2004, GSF Neuherberg (poster).
• Wichern F, Hafeel K (2004): The fungal-bacterial ratio: Tipping the balance for soil health. Soils are Alive Newsletter 3(3), University of Western Australia.
• Wichern F, Luedeling E, Müller T, Joergensen RG, Buerkert A (2003): Field measurement of the CO₂ evolution rate under different crops in the mountain oasis Bald Seet, Oman. Deutscher Tropentag (poster).
• Wichern F, Müller T, Joergensen RG, Buerkert A (2003): Effects of manure quality and application methods on soil C and N turnover in a subtropical mountain oasis. German Tropical Conference (poster).
• Wichern F, Müller T, Joergensen RG, Buerkert A (2003): Microbial activity in the soils of a subtropical mountain oasis in Oman. German Tropical Conference (poster).
• Joergensen RG, Wichern F, Richter C (2003): The loss of soil fertility on a Vertisol plot used as a kitchen garden in subtropical South Africa. Mitteilungen der DBG 102/1: 289–290.
• Hoffmann B, Wichern F (2003): Student marketing – Selling its ideals. ‘Küss die Uni wach’ competition, CHE, Gütersloh.
• Wichern F (2002): Biotope development concept for Sandkuhle Hamersen. Self-published.
• Wichern F, Richter C, Joergensen RG (2002): Soil fertility breakdown in soils of subtropical South Africa used as kitchen gardens. German Tropical Day (poster).
• Luedeling E, Siebert S, Wichern F, Aeschbach-Hertig W, Nagieb M, Müller T, Buerkert A (2002): The hydrology of mountain oases in northern Oman. German Tropical Conference (poster).