Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Sensitivity of labile carbon fractions to tillage and organic matter management and their potential as comprehensive soil quality indicators across pedoclimatic conditions in Europe
Bongiorno, Giulia ; Bünemann, Else K. ; Oguejiofor, Chidinma U. ; Meier, Jennifer ; Gort, Gerrit ; Comans, Rob ; Mäder, Paul ; Brussaard, Lijbert ; Goede, Ron de - \ 2019
Ecological Indicators 99 (2019). - ISSN 1470-160X - p. 38 - 50.
Dissolved organic carbon (DOC) - Hot water extractable carbon (HWEC) - Hydrophilic dissolved organic carbon (Hy-DOC) - Long-term experimental field (LTEs) - Particulate organic matter carbon (POMC) - Permanganate oxidizable carbon (POXC)

Soil quality is defined as the capacity of the soil to perform multiple functions, and can be assessed by measuring soil chemical, physical and biological parameters. Among soil parameters, labile organic carbon is considered to have a primary role in many soil functions related to productivity and environmental resilience. Our study aimed at assessing the suitability of different labile carbon fractions, namely dissolved organic carbon (DOC), hydrophilic DOC (Hy-DOC), permanganate oxidizable carbon (POXC, also referred to as Active Carbon), hot water extractable carbon (HWEC) and particulate organic matter carbon (POMC) as soil quality indicators in agricultural systems. To do so, we tested their sensitivity to two agricultural management factors (tillage and organic matter input) in 10 European long-term field experiments (LTEs), and we assessed the correlation of the different labile carbon fractions with physical, chemical and biological soil quality indicators linked to soil functions. We found that reduced tillage and high organic matter input increase concentrations of labile carbon fractions in soil compared to conventional tillage and low organic matter addition, respectively. POXC and POMC were the most sensitive fractions to both tillage and fertilization across the 10 European LTEs. In addition, POXC was the labile carbon fraction most positively correlated with soil chemical (total organic carbon, total nitrogen, and cation exchange capacity), physical (water stable aggregates, water holding capacity, bulk density) and biological soil quality indicators (microbial biomass carbon and nitrogen, and soil respiration). We conclude that POXC represents a labile carbon fraction sensitive to soil management and that is the most informative about total soil organic matter, nutrients, soil structure, and microbial pools and activity, parameters commonly used as indicators of various soil functions, such as C sequestration, nutrient cycling, soil structure formation and soil as a habitat for biodiversity. Moreover, POXC measurement is relatively cheap, fast and easy. Therefore, we suggest measuring POXC as the labile carbon fraction in soil quality assessment schemes in addition to other valuable soil quality indicators.

Crop traits drive soil carbon sequestration under organic farming
García-Palacios, Pablo ; Gattinger, Andreas ; Bracht-Jørgensen, Helene ; Brussaard, Lijbert ; Carvalho, Filipe ; Castro, Helena ; Clément, Jean Christophe ; Deyn, Gerlinde De; Hertefeldt, Tina D'; Foulquier, Arnaud ; Hedlund, Katarina ; Lavorel, Sandra ; Legay, Nicolas ; Lori, Martina ; Mäder, Paul ; Martínez-García, Laura B. ; Martins da Silva, Pedro ; Muller, Adrian ; Nascimento, Eduardo ; Reis, Filipa ; Symanczik, Sarah ; Paulo Sousa, José ; Milla, Rubén - \ 2018
Journal of Applied Ecology 55 (2018)5. - ISSN 0021-8901 - p. 2496 - 2505.
climate change mitigation - crop residue - ecological intensification - leaf nitrogen - meta-analysis - organic farming - resource economics traits - soil carbon stocks

Organic farming (OF) enhances top soil organic carbon (SOC) stocks in croplands compared with conventional farming (CF), which can contribute to sequester C. As farming system differences in the amount of C inputs to soil (e.g. fertilization and crop residues) are not enough to explain such increase, shifts in crop residue traits important for soil C losses such as litter decomposition may also play a role. To assess whether crop residue (leaf and root) traits determined SOC sequestration responses to OF, we coupled a global meta-analysis with field measurements across a European-wide network of sites. In the meta-analysis, we related crop species averages of leaf N, leaf-dry matter content, fine-root C and N, with SOC stocks and sequestration responses in OF vs. CF. Across six European sites, we measured the management-induced changes in SOC stocks and leaf litter traits after long-term ecological intensive (e.g. OF) vs. CF comparisons. Our global meta-analysis showed that the positive OF-effects on soil respiration, SOC stocks, and SOC sequestration rates were significant even in organic farms with low manure application rates. Although fertilization intensity was the main driver of OF-effects on SOC, leaf and root N concentrations also played a significant role. Across the six European sites, changes towards higher leaf litter N in CF also promoted lower SOC stocks. Our results highlight that crop species displaying traits indicative of resource-acquisitive strategies (e.g. high leaf and root N) increase the difference in SOC between OF and CF. Indeed, changes towards higher crop residue decomposability was related with decreased SOC stocks under CF across European sites. Synthesis and applications. Our study emphasizes that, with management, changes in crop residue traits contribute to the positive effects of organic farming (OF) on soil carbon sequestration. These results provide a clear message to land managers: the choice of crop species, and more importantly their functional traits (e.g. leave and root nitrogen), should be considered in addition to management practices and climate, when evaluating the potential of OF for climate change mitigation.

Crop pests and predators exhibit inconsistent responses to surrounding landscape composition
Karp, Daniel S. ; Chaplin-Kramer, Rebecca ; Meehan, Timothy D. ; Martin, Emily A. ; Declerck, Fabrice ; Grab, Heather ; Gratton, Claudio ; Hunt, Lauren ; Larsen, Ashley E. ; Martínez-Salinas, Alejandra ; O’Rourke, Megan E. ; Rusch, Adrien ; Poveda, Katja ; Jonsson, Mattias ; Rosenheim, Jay A. ; Schellhorn, Nancy A. ; Tscharntke, Teja ; Wratten, Stephen D. ; Zhang, Wei ; Iverson, Aaron L. ; Adler, Lynn S. ; Albrecht, Matthias ; Alignier, Audrey ; Angelella, Gina M. ; Zubair Anjum, Muhammad ; Avelino, Jacques ; Batáry, Péter ; Baveco, Johannes M. ; Bianchi, Felix J.J.A. ; Birkhofer, Klaus ; Bohnenblust, Eric W. ; Bommarco, Riccardo ; Brewer, Michael J. ; Caballero-López, Berta ; Carrière, Yves ; Carvalheiro, Luísa G. ; Cayuela, Luis ; Centrella, Mary ; Ćetković, Aleksandar ; Henri, Dominic Charles ; Chabert, Ariane ; Costamagna, Alejandro C. ; La Mora, Aldo De; Kraker, Joop De; Desneux, Nicolas ; Diehl, Eva ; Diekötter, Tim ; Dormann, Carsten F. ; Eckberg, James O. ; Entling, Martin H. ; Fiedler, Daniela ; Franck, Pierre ; Veen, F.J.F. van; Frank, Thomas ; Gagic, Vesna ; Garratt, Michael P.D. ; Getachew, Awraris ; Gonthier, David J. ; Goodell, Peter B. ; Graziosi, Ignazio ; Groves, Russell L. ; Gurr, Geoff M. ; Hajian-Forooshani, Zachary ; Heimpel, George E. ; Herrmann, John D. ; Huseth, Anders S. ; Inclán, Diego J. ; Ingrao, Adam J. ; Iv, Phirun ; Jacot, Katja ; Johnson, Gregg A. ; Jones, Laura ; Kaiser, Marina ; Kaser, Joe M. ; Keasar, Tamar ; Kim, Tania N. ; Kishinevsky, Miriam ; Landis, Douglas A. ; Lavandero, Blas ; Lavigne, Claire ; Ralec, Anne Le; Lemessa, Debissa ; Letourneau, Deborah K. ; Liere, Heidi ; Lu, Yanhui ; Lubin, Yael ; Luttermoser, Tim ; Maas, Bea ; Mace, Kevi ; Madeira, Filipe ; Mader, Viktoria ; Cortesero, Anne Marie ; Marini, Lorenzo ; Martinez, Eliana ; Martinson, Holly M. ; Menozzi, Philippe ; Mitchell, Matthew G.E. ; Miyashita, Tadashi ; Molina, Gonzalo A.R. ; Molina-Montenegro, Marco A. ; O’Neal, Matthew E. ; Opatovsky, Itai ; Ortiz-Martinez, Sebaastian ; Nash, Michael ; Östman, Örjan ; Ouin, Annie ; Pak, Damie ; Paredes, Daniel ; Parsa, Soroush ; Parry, Hazel ; Perez-Alvarez, Ricardo ; Perović, David J. ; Peterson, Julie A. ; Petit, Sandrine ; Philpott, Stacy M. ; Plantegenest, Manuel ; Plećaš, Milan ; Pluess, Therese ; Pons, Xavier ; Potts, Simon G. ; Pywell, Richard F. ; Ragsdale, David W. ; Rand, Tatyana A. ; Raymond, Lucie ; Ricci, Benoît ; Sargent, Chris ; Sarthou, Jean-Pierre ; Saulais, Julia ; Schäckermann, Jessica ; Schmidt, Nick P. ; Schneider, Gudrun ; Schüepp, Christof ; Sivakoff, Frances S. ; Smith, Henrik G. ; Stack Whitney, Kaitlin ; Stutz, Sonja ; Szendrei, Zsofia ; Takada, Mayura B. ; Taki, Hisatomo ; Tamburini, Giovanni ; Thomson, Linda J. ; Tricault, Yann ; Tsafack, Noelline ; Tschumi, Matthias ; Valantin-Morison, Muriel ; Trinh, Mai Van; Werf, Wopke Van Der; Vierling, Kerri T. ; Werling, Ben P. ; Wickens, Jennifer B. ; Wickens, Victoria J. ; Woodcock, Ben A. ; Wyckhuys, Kris ; Xiao, Haijun ; Yasuda, Mika ; Yoshioka, Akira - \ 2018
Proceedings of the National Academy of Sciences of the United States of America 115 (2018)33. - ISSN 0027-8424 - p. E7863 - E7870.
The idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies.
Effects of agricultural management practices on soil quality : A review of long-term experiments for Europe and China
Bai, Zhanguo ; Caspari, Thomas ; Gonzalez, Maria Ruiperez ; Batjes, Niels H. ; Mäder, Paul ; Bünemann, Else K. ; Goede, Ron de; Brussaard, Lijbert ; Xu, Minggang ; Ferreira, Carla Sofia Santos ; Reintam, Endla ; Fan, Hongzhu ; Mihelič, Rok ; Glavan, Matjaž ; Tóth, Zoltán - \ 2018
Agriculture, Ecosystems and Environment 265 (2018). - ISSN 0167-8809 - p. 1 - 7.
Agricultural management practices - Literature review - Long-term field experiments - Response ratio - Soil quality indicators
In this paper we present effects of four paired agricultural management practices (organic matter (OM) addition versus no organic matter input, no-tillage (NT) versus conventional tillage, crop rotation versus monoculture, and organic agriculture versus conventional agriculture) on five key soil quality indicators, i.e., soil organic matter (SOM) content, pH, aggregate stability, earthworms (numbers) and crop yield. We have considered organic matter addition, no-tillage, crop rotation and organic agriculture as “promising practices”; no organic matter input, conventional tillage, monoculture and conventional farming were taken as the respective references or “standard practice” (baseline). Relative effects were analysed through indicator response ratio (RR) under each paired practice. For this we considered data of 30 long-term experiments collected from 13 case study sites in Europe and China as collated in the framework of the EU-China funded iSQAPER project. These were complemented with data from 42 long-term experiments across China and 402 observations of long-term trials published in the literature. Out of these, we only considered experiments covering at least five years. The results show that OM addition favourably affected all the indicators under consideration. The most favourable effect was reported on earthworm numbers, followed by yield, SOM content and soil aggregate stability. For pH, effects depended on soil type; OM input favourably affected the pH of acidic soils, whereas no clear trend was observed under NT. NT generally led to increased aggregate stability and greater SOM content in upper soil horizons. However, the magnitude of the relative effects varied, e.g. with soil texture. No-tillage practices enhanced earthworm populations, but not where herbicides or pesticides were applied to combat weeds and pests. Overall, in this review, yield slightly decreased under NT. Crop rotation had a positive effect on SOM content and yield; rotation with ley very positively influenced earthworms’ numbers. Overall, crop rotation had little impact on soil pH and aggregate stability − depending on the type of intercrop; alternatively, rotation of arable crops only resulted in adverse effects. A clear positive trend was observed for earthworm abundance under organic agriculture. Further, organic agriculture generally resulted in increased aggregate stability and greater SOM content. Overall, no clear trend was found for pH; a decrease in yield was observed under organic agriculture in this review.
Soil Quality - a critical review
Bunemann, Else K. ; Bongiorno, G. ; Bai, Z.G. ; Creamer, Rachel ; Deyn, G.B. de; Goede, R.G.M. de; Fleskens, L. ; Geissen, V. ; Kuijper, T.W.M. ; Mäder, Paul ; Pulleman, M.M. ; Sukkel, W. ; Groenigen, J.W. van; Brussaard, L. - \ 2018
Soil Biology and Biochemistry 120 (2018). - ISSN 0038-0717 - p. 105 - 125.
Sampling and analysis or visual examination of soil to assess its status and use potential is widely practiced from plot to national scales. However, the choice of relevant soil attributes and interpretation of measurements are not straightforward, because of the complexity and site-specificity of soils, legacy effects of previous land use, and trade-offs between ecosystem services. Here we review soil quality and related concepts, in terms of definition, assessment approaches, and indicator selection and interpretation. We identify the most frequently used soil quality indicators under agricultural land use. We find that explicit evaluation of soil quality with respect to specific soil threats, soil functions and ecosystem services has rarely been implemented, and few approaches provide clear interpretation schemes of measured indicator values. This limits their adoption by land managers as well as policy. We also consider novel indicators that address currently neglected though important soil properties and processes, and we list the crucial steps in the development of a soil quality assessment procedure that is scientifically sound and supports management and policy decisions that account for the multi-functionality of soil. This requires the involvement of the pertinent actors, stakeholders and end-users to a much larger degree than practiced to date.
Organic farming enhances soil microbial abundance and activity—A meta-analysis and meta-Regression
Lori, Martina ; Symnaczik, Sarah ; Mäder, Paul ; Deyn, Gerlinde De; Gattinger, Andreas - \ 2017
PLoS One 12 (2017)7. - ISSN 1932-6203
Population growth and climate change challenge our food and farming systems and provide arguments for an increased intensification of agriculture. A promising option is eco-functional intensification through organic farming, an approach based on using and enhancing internal natural resources and processes to secure and improve agricultural productivity, while minimizing negative environmental impacts. In this concept an active soil microbiota plays an important role for various soil based ecosystem services such as nutrient cycling, erosion control and pest and disease regulation. Several studies have reported a positive effect of organic farming on soil health and quality including microbial community traits. However, so far no systematic quantification of whether organic farming systems comprise larger and more active soil microbial communities compared to conventional farming systems was performed on a global scale. Therefore, we conducted a meta-analysis on current literature to quantify possible differences in key indicators for soil microbial abundance and activity in organic and conventional cropping systems. All together we integrated data from 56 mainly peer-reviewed papers into our analysis, including 149 pairwise comparisons originating from different climatic zones and experimental duration ranging from 3 to more than 100 years. Overall, we found that organic systems had 32% to 84% greater microbial biomass carbon, microbial biomass nitrogen, total phospholipid fatty-acids, and dehydrogenase, urease and protease activities than conventional systems. Exclusively the metabolic quotient as an indicator for stresses on microbial communities remained unaffected by the farming systems. Categorical subgroup analysis revealed that crop rotation, the inclusion of legumes in the crop rotation and organic inputs are important farming practices affecting soil microbial community size and activity. Furthermore, we show that differences in microbial size and activity between organic and conventional farming systems vary as a function of land use (arable, orchards, and grassland), plant life cycle (annual and perennial) and climatic zone. In summary, this study shows that overall organic farming enhances total microbial abundance and activity in agricultural soils on a global scale.
Public and private standards for dried culinary herbs and spices—Part II : Production and product standards for ensuring microbiological safety
Schaarschmidt, Sara ; Spradau, Franziska ; Mank, Helmut ; Banach, Jennifer L. ; Fels, Ine van der; Hiller, Petra ; Appel, Bernd ; Bräunig, Juliane ; Wichmann-Schauer, Heidi ; Mader, Anneluise - \ 2016
Food Control 70 (2016). - ISSN 0956-7135 - p. 360 - 370.
Bacillus cereus - Clostridium perfringens - Food safety testing - Good practices - Microbiological criteria - Salmonella spp.

Dried culinary herbs and spices (DCHS) are minor food components with widespread use. Despite their low water activity, some microorganisms—including pathogenic and toxigenic ones—can survive in DCHS. The addition of microbial contaminated DCHS to ready-to-eat food in combination with improper food storage can pose a serious health risk for the consumer. In the past, several food-borne disease outbreaks were related to microbial contaminated spices. The aim of this study was to provide an overview on (i) spice/herb production standards important for promoting food safety by preventing microbial contaminations, (ii) public and private standards providing microbiological criteria to assess the microbiological safety of DCHS, and (iii) product testing performed by DCHS producing/processing businesses to comply with these standards. For that, a literature search and a survey among herb/spice businesses were conducted. Several good practices and production guidelines specific for the primary production and/or processing of culinary herbs and spices were found. Microbiological criteria specific for DCHS are usually rare, but some national standards (mostly of non-EU member states) as well as recommendations by private bodies could be identified. By EU law, no mandatory microbiological criteria specific for DCHS are laid down. The survey indicated a frequent application of business-to-business agreements. The microbiological quality of DCHS was tested by the survey participants mainly in a routine manner by checking every lot or based on buyer–seller agreements. Risk-based testing was less common, which differed to chemical safety testing. Upon import into the EU, testing appeared to be performed predominantly in a routine manner for the pathogenic bacteria Salmonella spp., sulphite-reducing clostridia (including Clostridium perfringens), Bacillus cereus, and Staphylococcus aureus.

Shallow non-inversion tillage in organic farming maintains crop yields and increases soil C stocks : a meta-analysis
Cooper, Julia ; Baranski, Marcin ; Stewart, Gavin ; Nobel-de Lange, Majimcha ; Bàrberi, Paolo ; Fließbach, Andreas ; Peigné, Josephine ; Berner, Alfred ; Brock, Christopher ; Casagrande, Marion ; Crowley, Oliver ; David, Christophe ; Vliegher, Alex De; Döring, Thomas F. ; Dupont, Aurélien ; Entz, Martin ; Grosse, Meike ; Haase, Thorsten ; Halde, Caroline ; Hammerl, Verena ; Huiting, Hilfred ; Leithold, Günter ; Messmer, Monika ; Schloter, Michael ; Sukkel, Wijnand ; Heijden, Marcel G.A. van der; Willekens, Koen ; Wittwer, Raphaël ; Mäder, Paul - \ 2016
Agronomy for Sustainable Development 36 (2016)1. - ISSN 1774-0746
Conservation agriculture - Conservation tillage - Crop yield - Meta-analysis - Minimum tillage - No-till - Organic farming - Reduced tillage - Soil C - Weeds

Reduced tillage is increasingly promoted to improve sustainability and productivity of agricultural systems. Nonetheless, adoption of reduced tillage by organic farmers has been slow due to concerns about nutrient supply, soil structure, and weeds that may limit yields. Here, we compiled the results from both published and unpublished research comparing deep or shallow inversion tillage, with various categories of reduced tillage under organic management. Shallow refers to less than 25 cm. We found that (1) division of reduced tillage practices into different classes with varying degrees of intensity allowed us to assess the trade-offs between reductions in tillage intensity, crop yields, weed incidence, and soil C stocks. (2) Reducing tillage intensity in organic systems reduced crop yields by an average of 7.6 % relative to deep inversion tillage with no significant reduction in yield relative to shallow inversion tillage. (3) Among the different classes of reduced tillage practice, shallow non-inversion tillage resulted in non-significant reductions in yield relative to deep inversion; whereas deep non-inversion tillage resulted in the largest yield reduction, of 11.6 %. (4) Using inversion tillage to only a shallow depth resulted in minimal reductions in yield, of 5.5 %, but significantly higher soil C stocks and better weed control. This finding suggests that this is a good option for organic farmers wanting to improve soil quality while minimizing impacts on yields. (5) Weeds were consistently higher, by about 50 %, when tillage intensity was reduced, although this did not always result in reduced yields.

Tillage as a driver of change in weed communities : A functional perspective
Armengot, L. ; Blanco-Moreno, J.M. ; Bàrberi, P. ; Bocci, G. ; Carlesi, S. ; Aendekerk, R. ; Berner, A. ; Celette, F. ; Grosse, M. ; Huiting, H. ; Kranzler, A. ; Luik, A. ; Mäder, P. ; Peigné, J. ; Stoll, E. ; Delfosse, P. ; Sukkel, W. ; Surböck, A. ; Westaway, S. ; Sans, F.X. - \ 2016
Agriculture, Ecosystems and Environment 222 (2016). - ISSN 0167-8809 - p. 276 - 285.
Community weighted means - Crop type - Meta-analysis - Reduced tillage - Weed traits - Weed-crop competition

The adoption of non-inversion tillage practices has been widely promoted due to their potential benefits in reducing energy consumption and greenhouse emissions as well as improving soil fertility. However, the lack of soil inversion usually increases weed infestations and changes the composition of the weed community. Weed management is still a main drawback for the wider adoption of reduced tillage practices. However, it is not entirely clear whether these changes in weed communities are a consequence of non-random filters on the functional attributes of weed species and may thus affect the potential weed-crop competition relationship.Here, we analyse the changes in weed diversity, community composition, and the functional attributes of weed communities under reduced (non-inversion) and conventional (inversion) tillage. We discuss their potential effects on the competitiveness against crop production using data from two crops of seven on-going organic and low-input field trials in different climatic regions across Europe. Weeds were evaluated after post-emergence weed control methods. We used the community weighted mean values of the life form (annuals versus perennials), specific leaf area, seed weight, canopy height, seed bank longevity, soil nutrient conditions affinity, beginning of flowering and flowering span. Moreover, the effect of the crop type on the functional attributes was also evaluated.Overall, the tillage system affected the composition and functional attributes of the weed communities. Weed community changes may imply a reduction in weed-crop competition under both tillage systems. For instance, weed communities under reduced tillage were potentially less competitive because they were shorter and had less affinity to nutrients. On the other hand, weed communities under conventional tillage had potentially less seed production and a lower abundance of perennial species. Our study thus supports tillage as an important driver of the functional attributes of weed communities, but both tillage systems can have their downside. However, the crop type was overall more relevant than the tillage in determining most of the trait values of the weed communities.

Influence of reduced tillage on earthworm and microbial communities under organic arable farming
Kuntz, M. ; Berner, A. ; Gattinger, A. ; Scholberg, J.M.S. ; Mäder, P. ; Pfiffner, L. - \ 2013
Pedobiologia 56 (2013)4-6. - ISSN 0031-4056 - p. 251 - 260.
fumigation-extraction method - conservation tillage - cropping systems - lumbricus-terrestris - ecosystem services - soil fertility - biomass - management - abundance - dynamics
Although reduced tillage is an agricultural practice reported to decrease soil erosion and external inputs while enhancing soil fertility, it has still rarely been adopted by European organic farmers. The objective of this study was to assess the long-term interactive effects of tillage (conventional (CT) vs. reduced (RT)) and fertilization (slurry (S) vs. composted manure/slurry (MCS)) on earthworms and microbial communities in a clay soil under spelt in an organic 6-year crop rotation. Earthworm populations (species, density and biomass, cocoons) were investigated by handsorting the soil nine years after initial implementation of the treatments. Soil microbial carbon (Cmic) and nitrogen (Nmic) were measured by chloroform-fumigation extraction and a simplified phospholipid fatty acid (PLFA) analysis was used to separate for populations of bacteria, fungi and protozoa. Significantly increased total earthworm density in RT plots was mainly attributed to increased numbers of juveniles. Moreover, we found five times more cocoons with RT. Species richness was not affected by the treatments, but tillage treatments had differentially affected populations at the species-level. In addition, cluster analysis at the community level revealed two distinct groups of plots in relation to tillage treatments. In RT plots Cmic increased in the 0–10 cm and 10–20 cm soil layers, while PLFA concentrations indicative of Gram-negative bacteria, fungi and protozoa only increased in the topsoil. Lower bacteria-to-fungi ratios in the upper soil layer of RT plots indicated a shift to fungal-based decomposition of organic matter whereas a higher Cmic-to-Corg ratio pointed towards enhanced substrate availability. Slurry application decreased microbial biomass and enhanced density of juvenile anecic earthworms but overall fertilization effect was weak and no interactions with tillage were found. In conclusion, tillage is a major driver in altering communities of earthworms and microorganisms in arable soils. The use of reduced tillage provides an approach for eco-intensification by enhancing inherent soil biota functions under organic arable farming.
Long-term organic farming fosters below and aboveground biota: Implications for soil quality, biological control and productivity
Birkhofer, K. ; Bezemer, T.M. ; Bloem, J. ; Bonkowski, M. ; Christensen, S. ; Dubois, D. ; Ekelund, F. ; Fliessbach, A. ; Gunst, L. ; Hedlund, K. ; Mäder, P. ; Mikola, J. ; Robin, C. ; Setälä, H. ; Tatin-Froux, F. ; Putten, W.H. van der; Scheu, S. - \ 2008
Soil Biology and Biochemistry 40 (2008)9. - ISSN 0038-0717 - p. 2297 - 2308.
microbial community structure - food-web - agricultural systems - generalist predators - mycorrhizal fungi - alternative prey - biomass - nitrogen - agroecosystems - management
Organic farming may contribute substantially to future agricultural production worldwide by improving soil quality and pest control, thereby reducing environmental impacts of conventional farming. We investigated in a comprehensive way soil chemical, as well as below and aboveground biological parameters of two organic and two conventional wheat farming systems that primarily differed in fertilization and weed management strategies. Contrast analyses identified management related differences between ¿herbicide-free¿ bioorganic (BIOORG) and biodynamic (BIODYN) systems and conventional systems with (CONFYM) or without manure (CONMIN) and herbicide application within a long-term agricultural experiment (DOK trial, Switzerland). Soil carbon content was significantly higher in systems receiving farmyard manure and concomitantly microbial biomass (fungi and bacteria) was increased. Microbial activity parameters, such as microbial basal respiration and nitrogen mineralization, showed an opposite pattern, suggesting that soil carbon in the conventional system (CONFYM) was more easily accessible to microorganisms than in organic systems. Bacterivorous nematodes and earthworms were most abundant in systems that received farmyard manure, which is in line with the responses of their potential food sources (microbes and organic matter). Mineral fertilizer application detrimentally affected enchytraeids and Diptera larvae, whereas aphids benefited. Spider abundance was favoured by organic management, most likely a response to increased prey availability from the belowground subsystem or increased weed coverage. In contrast to most soil-based, bottom-up controlled interactions, the twofold higher abundance of this generalist predator group in organic systems likely contributed to the significantly lower abundance of aboveground herbivore pests (aphids) in these systems. Long-term organic farming and the application of farmyard manure promoted soil quality, microbial biomass and fostered natural enemies and ecosystem engineers, suggesting enhanced nutrient cycling and pest control. Mineral fertilizers and herbicide application, in contrast, affected the potential for top-down control of aboveground pests negatively and reduced the organic carbon levels. Our study indicates that the use of synthetic fertilizers and herbicide application changes interactions within and between below and aboveground components, ultimately promoting negative environmental impacts of agriculture by reducing internal biological cycles and pest control. On the contrary, organic farming fosters microbial and faunal decomposers and this propagates into the aboveground system via generalist predators thereby increasing conservation biological control. However, grain and straw yields were 23% higher in systems receiving mineral fertilizers and herbicides reflecting the trade-off between productivity and environmental responsibility.
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