Institute For Agrarokologie

Freising, Germany

Institute For Agrarokologie

Freising, Germany
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Shahbaz M.,University of Gottingen | Kuzyakov Y.,University of Gottingen | Kuzyakov Y.,Kazan Federal University | Maqsood S.,University of Gottingen | And 2 more authors.
Land Degradation and Development | Year: 2017

Crop residues and manure are important sources of carbon (C) for soil organic matter (SOM) formation. Crop residue return increases by nitrogen (N) fertilization because of higher plant productivity, but this often results only in minor increases of SOM. In our study, we show how N fertilization and organic C additions affected SOM and its fractions within a 32-year-long field-experiment at Puch, Germany. Five organic additions, no-addition (control), manure, slurry, straw and straw + slurry, were combined with three mineral N fertilization rates (no, medium and high fertilization), which resulted in 1·17–4·86 Mg C-input ha-1 y-1. Topsoil (0–25 cm) SOM content increased with N fertilization, mainly because of the C in free light fraction (f-LF). In contrast, subsoil (25–60 cm) SOM decreased with N fertilization, probably because of roots' relocation in Ap horizon with N fertilization at the surface. Despite high inputs, straw contributed little to f-LF but prevented C losses from the mineral-associated SOM fraction (ρ > 1·6 g cm-3) with N fertilization, which was observed without straw addition. Above (straw) and belowground (roots) residues had opposite effects on SOM fractions. Root C retained longer in the light-fractions and was responsible for SOM increase with N fertilization. Straw decomposed rapidly (from f-LF) and fueled the mineral-associated SOM fraction. We conclude that SOM content and composition depended not only on residue quantity, which can be managed by the additions and N fertilization, but also on the quality of organics. This should be considered for maintaining the SOM level, C sequestration, and soil fertility. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Deubert M.,Institute For Agrarokologie | Trapp M.,Institute For Agrarokologie | Krohn K.,Berlin | Kunast C.,Otterstadt
Naturschutz und Landschaftsplanung | Year: 2016

There is a variety of areas in open agricultural landscapes and settlement areas that are suitable for ecological optimisation. “Eh da” is a southern German idiom meaning something like “available anyway” or “at hand, but unplanned”. Accordingly, the term “Eh da-areas” refers to the total sum of areas along paths, traffic ways and watercourses, railway embankments, traffic islands and the various municipal green spaces. According to geodata analyses these areas account for a significant share of German landscapes, albeit with marked regional differences. Given the increasing demand for agriculture land, housing development and nature conservation we would be well-advised to pay more attention to “Eh da”-sites, both in terms of isolated plots and in the context of biotope connectivity. Current “Eh da”-projects focus on bees as protection targets which need breeding and foraging habitats. As illustrated by a case study, local communities would qualify as organising institutions. “Eh da”-projects consist of different phases, with planning and communication being core elements. © 2016, Verlag Eugen Ulmer. All rights reserved.

Brock C.,Justus Liebig University | Fliessbach A.,Forschungsinstitut For Biologischen Landbau Fibl | Oberholzer H.-R.,ART Agroscope Reckenholz Tänikon | Schulz F.,Justus Liebig University | And 8 more authors.
Journal of Plant Nutrition and Soil Science | Year: 2011

The aim of this study was to evaluate the interaction between yield levels of nonleguminous crops and soil organic matter (SOM) under the specific conditions of organic and conventional farming, respectively, and to identify implications for SOM management in arable farming considering the farming system (organic vs. conventional). For that purpose, correlations between yield levels of nonlegume crops and actual SOM level (Corg, Nt, Chwe, Nhwe) as well as SOM-level development were examined including primary data from selected treatments of seven long-term field experiments in Germany and Switzerland. Yield levels of nonlegume crops were positively correlated with SOM levels, but the correlation was significant only under conditions of organic farming, and not with conventional farming treatments. While absolute SOM levels had a positive impact on yield levels of nonlegumes, the yield levels of nonlegumes and SOM-level development over time correlated negatively. Due to an increased demand of N from SOM mineralization, higher yield levels of nonlegumes obviously indicate an increased demand for OM supply to maintain SOM levels. Since this observation is highly significant for farming without mineral-N fertilization but not for farming with such fertilization, we conclude that the demand of SOM-level maintenance or enhancement and thus adequate SOM management is highly relevant for crop production in organic farming both from an agronomical and ecological point of view. Under conventional management, the agronomic relevance of SOM with regard to nutrient supply is much lower than under organic management. However, it has to be considered that we excluded other possible benefits of SOM in our survey that may be highly relevant for conventional farming as well.© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Auerswald K.,TU Munich | Mayer F.,Institute For Agrarokologie | Schnyder H.,TU Munich
Nutrient Cycling in Agroecosystems | Year: 2010

Excreta deposition redistributes, separates and concentrates nutrients and thus affects sward heterogeneity and environment. Concentration occurs within excrement patches, but also at a larger scale when excreta are not randomly deposited. Thus, detecting excrement patterns and their underlying rules is essential to understand nutrient heterogeneity within a pasture. Two urine and six dung-patch distributions from six grazing periods were mapped on a 0. 6 ha rotationally grazed cattle pasture. Excreta density was determined by creating Thiessen polygons. The Thiessen method was preferred to previously used predefined grids, because the resulting pattern is not obscured by the layout and resolution of such a grid. GIS, geostatistical simulation and geostatistical analysis were then applied to detect patterns. All urine and dung distributions had a similar dominant pattern with only small (<5%) random variation. Excreta density increased with distance to the fence, decreasing slope gradient and towards the crest. The pattern evolved preferably during night at preferred resting areas when the animals rarely moved while urination and defecation were still served. Feed-back mechanisms attenuated some of the nocturnal pattern because resting places with high excrement density were avoided during grazing despite their high productivity. Validation with data from two independent studies showed that excrement patterns are common and governed by similar principles where site conditions are similar. Excrement pattern may be enhanced or attenuated by deliberate adjustment of pasture properties relative to terrain properties and the placement of installations such as fences. Placing watering or feeding stations close to preferred resting places and fences at a large distance to them will increase heterogeneity while night shedding would reduce it. © 2009 Springer Science+Business Media B.V.

Eisele M.,Bayerisches Landesamt fur Umwelt Dienststelle Hof | Simon-O'Malley S.,Bayerisches Landesamt fur Umwelt Dienststelle Hof | Wendland M.,Institute For Agrarokologie
Wasser und Abfall | Year: 2012

In the context of the EU Water Framework Directive (WFD) implementation, the structures of models for calculating the nitrate contamination and transport into the groundwater of bedrocks will be tested. Thereby, a nitrate contamination model for unsaturated zone will be coupled with numerical flow and transport models in the groundwater. The models should serve as tool for impact assessment of measures for pollution reduction.

Heitkamp F.,University of Gottingen | Heitkamp F.,Ohio State University | Wendland M.,Institute For Agrarokologie | Offenberger K.,Institute For Agrarokologie | Gerold G.,University of Gottingen
Geoderma | Year: 2012

Effects of fertilisation and cropland management on soil organic carbon (SOC) dynamics can be assessed best in long-term experiments. Using data from the long-term fertilisation experiment in Puch, Germany (part of the series "Internationale Organische Stickstoff Dauerversuche", IOSDV), we tested the performance of the Rothamsted Carbon Model 26.3 (RothC). The objectives of this work were: (i) quantify the C-input and the efficiency of SOC stabilisation, (ii) test the performance of different input estimates on predictive power of the RothC and (iii) test implementations of residue quality and C-saturation on model predictions. The experiment is a full-factorial strip design, the factors being "organic amendment" and "level of N-fertiliser". Each treatment was replicated three times. The crop rotation is silage maize-winter wheat-winter barley. Five levels of the factor "organic amendment" were considered: (i) CON: no organic amendment; (ii) SLU: slurry application (on average 0.8MgCha -1year -1); (iii) FYM: application of farmyard manure (30 to 40Mgha -1 fresh mass every third year to maize, on average 1.0MgCha -1year -1); (iv) STR: straw incorporation after harvest of wheat and barley (depending on straw yield on average 0.7 to 2.2MgCha -1year -1); (v) STSL: slurry application plus straw incorporation (on average 1.1 to 2.4MgCha -1year -1). All treatments (including CON) were combined with five different levels of N-fertilisation (N0 to N4), whereas N0 was nil N application and N4 averaged 177kgNha -1year -1. N-rates increased gradually and differed depending on the crop. Starting values for SOC stocks (Mgha -1) were measured in 1983 as a mean among N-rates for organic amendment treatments (CON: 42; SLU: 39.8; FYM: 40.5; STR 39.8; STSL: 40.5). SOC stocks (0-25cm) in 2004 (35.5 to 46.6MgCha -1) were in the order STSL>FYM=SLU>STR=CON (p≤0.001). However, slightly different starting values indicated a higher loss of SOC after 21years in the CON (11-14%) compared to the STR treatments (1-10%). Effect of N-rate was not significant. The observed relation between change of SOC and C-input was quadratic (Y O=-13.4+7.5x-0.9x 2; R 2=0.74, p≤0.001), which contrasted the linear relationship predicted by RothC (Y P=-12.9+5.5x; R 2=0.97, p≤0.0001). Serious deviation between observed and predicted relationship occurred above C-inputs of 2.5MgCha -1year -1. Mechanistic explanation (e.g. C-saturation or increased mineralisation by N-fertilisation) for the observation needs further exploration, but implication on regional estimates for C-accumulation for different cropland management scenarios is obvious: potential gain in SOC storage by increasing C-inputs may be overestimated, at least under conditions of the Puch site. Independent model predictions (i.e. no parameter adjustment and independent estimation and measurement of C-input) were successful for treatments without straw incorporation (CON, SLU, FYM). Using a regression between crop yields and crop residue input yielded better results than using a constant belowground-to-aboveground biomass ratio. SOC stocks of treatments STR and STSL were seriously overestimated by the model. Using a higher decomposability of crop residue improved result only marginally and required the change of a standard parameter. Using a simple implementation of C-saturation improved predictions for STR and STSL but failed to simulate dynamics in all other treatments. Overall, our results showed that it is important to recognise that relation between SOC change and C-input is not necessarily linear. However, the RothC model predicted SOC dynamics well at lower input levels. Observation that a regression equation for input estimation is superior to a constant biomass ratio for modelling purposes has to be tested further. An implementation of residue quality or saturation capacity in the RothC model may be promising for a better mechanistic understanding of SOC dynamics. However, this requires careful calibration and will increase the number of parameters to be fitted. © 2011 Elsevier B.V.

Ruff M.,TU Munich | Kuhn G.,Institute For Agrarokologie | Heinz S.,Institute For Agrarokologie | Kollmann J.,TU Munich | Albrecht H.,TU Munich
Naturschutz und Landschaftsplanung | Year: 2013

Evaluation of Plant Species Diversity in Grasslands in Smallstructured Landscapes - A Methodological Study for Agri-environmental Schemes Result-oriented agri-environmental schemes provide a more effective conservation of biodiversity in agricultural landscapes than action-oriented programmes, the latter currently being recommended for farming practices with positive ecological impact. Their implementation requires target species which indicate biodiversity as well as a simple sampling method. Therefore, the aim of this study was to examine a list of target species for the assessment of plant biodiversity in meadows and to develop a suitable method to record these species. Survey methods with different accuracy were tested on 52 grassland sites in two distinct regions of Bavaria. Due to their close correlation with the total number of species, the number of target species proved to be a good indicator of biodiversity. Transects provided reliable results in detecting the target species, and could be performed easily and quickly. For the implementation on grassland parcels with a diagonal < 200 m transects are recommended with a length of 100 m along the longest diagonal. Sites with at least seven target species along this transect are considered as species-rich and eligible for funding.

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