Moos et al. (2020) · LANDBAUFORSCH · J Sustainable Organic Agric Syst · 70(2):113–128 DOI:10.3220/LBF1611932809000 113 RESEARCH ARTICLE Minor changes in collembolan communities under different organic crop rotations and tillage regimes Jan Hendrik Moos 1, 2, Stefan Schrader 2, and Hans Marten Paulsen 1 HIGHLIGHTS Received: March 27, 2020 • Species richness and abundance of collembolans are not affected by tillage Revised: June 17, 2020 and crop rotations in organic farming systems. Revised: August 24, 2020 • There is some evidence that the relative share of euedaphic collembolans is Accepted: September 10, 2020 an indicator of management impacts. • Collembolan communities are more influenced by crop type and crop cover than by specific crop rotations or differences in tillage regime. KEYWORDS soil biodiversity, eco-morphological index (EMI), soil tillage, organic matter Abstract collembolan individuals tended to increase in soil environ­ ments that offered more stable habitat conditions from An aim of organic farming is to reduce negative impacts of increased availability of organic matter. agricultural management practices on physical, chemical, and biological soil properties. A growing number of organic 1 Introduction farmers is trying out methods of reduced tillage to save costs, protect humus and to foster natural processes in the soil. Fur­ Agriculture impacts directly and severely on soil biodiver­ ther more, techniques like increasing crop rotation diversity sity (Orgiazzi et al., 2016). Negative effects are especially and reduced tillage are discussed under the topics of agro­ ex pected in intensively managed systems with simple crop­ ecology or ecological intensification also for implementation ping se quences (e.g. Eisenhauer, 2016). To foster sustainability, in non­organic farming systems. soil fertility, biodiversity and nutrient supply from the soil, The question arises as to whether these practices are organic farming uses diverse crop rotations, which include positively impacting on soil ecosystems and which indica­ different leguminous crops, and rely on organic fertilisation. tors can be used to describe these impacts. Collembolans are In organic mixed farming systems, crop nutrition relies on the a widely distributed group of the soil mesofauna. They are application of livestock manure and the inclusion of forage mainly characterised as secondary decomposers feeding on and grain legumes. Besides mixed farming systems including fungi and other microorganisms. We investigated the influ­ animal husbandry, stockless arable cropping systems without ence of different long­term organic crop rotations (mixed manure input are used in organic farming. Their fertilisation farming with animal husbandry versus stockless arable) and is based on N­fixation by legumes and input of crop residues the short term effects of two years of different tillage systems and green manure. In summary, that the main differences (conventional tillage versus reduced tillage) on the abun­ between crop rotations of organic farming systems with and dance, species richness, species composition, and selected without livestock keeping are the form of organic fertiliser species traits (life forms) of collembolan communities. used and the proportion of legumes. Although not significant, some trends are evident. Spe­ Regardless of the fertilisation regime, a common feature of cies composition of collembolan communities responded to most organic crop rotations is the use of a mouldboard plough, expected alterations in soil moisture mediated by different mainly for weed management. As the negative impacts of crop sequences and inter­annual effects rather than to dif­ regu lar ploughing for different soil functions are well known fer ent management practices. The proportion of euedaphic (Peigné et al., 2007), in recent years different approaches have 1 Thünen Institute of Organic Farming, Westerau, Germany 2 Thünen Institute of Biodiversity, Braunschweig, Germany CONTACT [email protected], [email protected] Moos et al. (2020) · LANDBAUFORSCH · J Sustainable Organic Agric Syst · 70(2):113–128 114 been presented to integrate reduced tillage practices into of stable habitat conditions (Jeffery et al., 2010), especially crop rotations in organic farming systems to enhance system on permanent pore space as they are not burrowing. On clay sustainability (e.g. Mäder and Berner, 2012; Moos et al., 2016). soils, reduced tillage can lead to a decrease in pore volume, In general, reducing tillage intensity has positive effects such which is likely to have a negative effect on euedaphic collem­ as reducing the risk of soil erosion or increased macroporosity. bolans (e.g. Dittmer and Schrader, 2000). Nevertheless, in organic farming, reducing the intensity of Compared to euedaphic collembolans, hemiedaphic soil tillage is hindered by specific challenges such as in creas­ and atmobiont species are less dependent on the soil struc­ ing weed pressure, restricted N­availability, or restrictions in ture, as they inhabit the upper soil layer, the litter layer, or crop choice (Peigné et al,. 2007). the soil surface. Other factors such as humidity near the soil The aim of our project was to investigate the influence of surface and shading influence these life­forms (see above, different management practices in organic cropping systems c.f. Pommer esche et al., 2017). Thus, relative proportions of on the soil macro­ and mesofauna. Complementing a report euedaphic, hemiedaphic and atmobiont species should indi­ about effects on earthworms (Moos et al., 2016), this paper cate an impact of soil tillage intensity. considers the influence of crops, crop rotations and tillage Besides fertilisation and tillage regimes, the characteris­ regimes on collembolans. tics of the cultivated crops influence soil conditions and The investigation of widely distributed soil fauna groups thereby organisms inhabiting the soil. Different crop classes such as earthworms and microarthropods, which hold key (e.g. cereals versus root crops) can influence evapotranspira­ positions within soil food webs, can shed light on the impact tion differently and thereby soil moisture and humidity of management practices on soil ecosystems. Collembolans on the soil surface. Legumes influence the soil specifically are likely to be good indicators for soil conditions because through their symbiosis with nitrogen fixing bacteria in root they are widely distributed (Hopkin, 1997). Due to short nodules. Some studies indicate positive effects of the pres­ life cycles of the species, composition and abundance of ence of legumes on collembolan abundance and diversity collem bolan communities are expected to rapidly adapt in grassland due to increased microbial biomass, and higher to and reflect environmental changes. This response might litter quality (e.g. Sabais et al., 2011). For arable land, some be further enhanced through their function as secondary studies have been conducted comparing the influence of decomposers, feeding on fungi and microorganisms, which simple crop rotations (without legumes) and more complex links them closer to the environment than predatory or her­ crop rotations (with legumes) on collembolan communities bivorous animals (Greenslade, 2007). (Andrén and Lagerlöf, 1983; Jagers Op Akkerhuis et al., 1988). The influence of organic fertilisers on collembolan com­ How ever, these studies did not give consistent results, with mu nities is still under debate. Platen and Glemnitz (2016) complex crop rotations having both positive and no effect on found a positive effect applying digestate from biogas collembolan abundance. pro duction on collembolan abundance in a two­year field In the study reported here, we examined how collem­ experiment. Kautz et al. (2006) showed a positive effect of bolan communities respond to different management annual applications of straw and green manure. Kanal (2004) practices in two organic arable crop rotations on the same also found a positive fertilisation effect when applying cat­ experimental station, i.e. under comparable soil­climate and tle manure but highlighted additional seasonal variations in agro­technical conditions. Effects of tillage and crop rotation, abundance. In contrast, Pommeresche et al. (2017) described as well as effects of crop classes and annual fluctuations (e.g. negative short­term effects of slurry application on collem­ precipitation), on species richness, abundance, and life­form bolan abundance, with more negative effects for epigeic and species composition of collembolan communities were than endogeic species. None of the studies found any con­ analysed. We focussed on the question which characteristics sistent effect on collembolan community composition. There­ of collembolan communities are indicative of the effects of fore, the influence of organic fertilisation on characteristics of different crop rotations or tillage regimes in organic farming. collembolan communities is at least mediated by the type of organic matter and the timing of application. 2 Material and methods As for organic fertilisation, there are different results from examinations of the effects of tillage intensity on collem bolan 2.1 Study site communities. Brennan et al. (2006) found that reduced tillage The study was conducted at the experimental station of the increases collembolan abundance, and Miyazawa et al. (2002) Thünen Institute of Organic Farming in Trenthorst/Wulmenau, ascribed the related negative effect of conventional tillage on