Browsing by Subject "Biologischer Landbau"

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Agriculture in responsibility for our common world
(2022) Raupp, Manfred G.; Thomas, Angelika; Schüle, Heinrich; Carabet, Alin Flavius; Salasan, Cosmin; Fora, Ciprian George; Weinmann, Markus; Madora GmbH; University of Hohenheim, Institute of Crop Science; Klara Bradacova
The vocational training course program “Agriculture in Responsibility for our common World” organised within the frame of the Banat Green Deal Project “GreenERDE” (Education and Research in the context of the digital and ecological transformation of agriculture in the Banat Region and Baden-Württemberg - towards resource efficiency and resilience) and delivered between June 2021 and May 2022 targets the knowledge and experience transfer to the farmer community in the Banat Region, Romania and other parts of the world. Current and future challenges, such as the ecological conversion and digital transformation of agricultural production, but also social, economic and cultural aspects haven been addressed transcending prevailing patterns. The innovative and relevant knowledge originating from practice, experiments, research or development projects throughout Europe and other continents is presented in a training format for interested participants.
Die Auswirkungen einer einmalig variierten Bodenbearbeitung auf Ertragsbildung, Verunkrautung und Bodennitratgehalt unter ökologischen Produktionsbedingungen
(2007) Häberle, Annette; Claupein, Wilhelm
Although organic farming is a very non-polluting kind of agriculture, nitrate leachate losses can also be found under this management. Restrictions in organic fertilization have the purpose to keep the nitrate leachate with soil tillage and crop rotation on a low level. Due to this aim field experiments were conducted to investigate the short-term effect of timing and method of cultivation after the harvest of legumes and crops with high-N crop residues on N mineralization, nitrate leaching, crop growth, diseases and weeds in wheat crops. The study was designed to compare the effects of the ?Schutz- und Ausgleichsverordnung? (SchALVO) in Baden-Württemberg and tillage strategies which are normally used in practice, like reduced and conventional tillage in autumn and to compare different times of conventional tillage in winter and spring in three different areas of Baden-Württemberg with typically soil types. The areas were located in the Main-Tauber-Kreis with soils from Keuper and shell lime, in the Gäu-Region with soils from löss and the Schwäbische Alb with soils of limestone. Especially organic farms use, for the admancement of yield und for the regulation of weed population, a timely and increased requirement of soil tillage. In the results of October 2002 till summer 2005 there was no significant influence of timing and method of cultivation, for example reduced tillage in autumn or tillage in winter or spring, on the productivity of organic farms. In the most cases the conditions on the experimental fields were very good resulting of a low weed density and a good farming management. On fields with a high density of perennial weeds the risk of multiplication of weed population persists even after a short-term variation of tillage. There were only a few, not significant differences in the development of wheat growth because of different soil tillage. The most differences were seen between the growth of winter wheat and summer wheat. The yield of summer wheat was not significantly lower than the yield of winter wheat. Summer wheat reached nearly the same yield potential with higher amounts of crude protein. Especially in areas with strong winters and low N-input the yield of summer wheat was higher than the yield of winter wheat. Because of a second peak of mineralization in spring there was a better adaptation of NO3-release to the growth of summer wheat after soil tillage in November, December and February. Because of the better utilization of soil-N from summer wheat the lower yield potential in comparison to winter wheat was relativised in the most areas. With regard to N mineralization a time displacement of soil tillage in winter or spring didnt reduce the N-mineralization before winter in all cases. But in this time displaced treatments there was a second peak in N-mineralization additional to the first peak in autumn. Short-term practice of reduced soil tillage did not reduce N-release in the field experiments. Altogether a time displaced soil tillage in winter or spring could be, based on the experiments, a practical alternative for N-conservation through winter with regard to N-mineralization as well as with regard to corn yield. With the cultivation of a fast-growing catch crop farmers could reach an additional reduction of mineralised N amount over winter. In the farming practice a well timed sowing of catch crops is not always possible, like it is shown in the experiments, but it should be kept in mind for N conservation.
Einfluss der Bearbeitungsintensität beim Umbruch von Luzerne-Kleegras auf die Stickstoffmineralisation zur Folgefrucht Winterweizen im organischen Landbau
(2003) Wald, Fabian; Claupein, Wilhelm
In the crop rotation of organic farming grass-legume mixtures play an important role due to the legumes´ ability to assimilate N. Ploughing-in of established grass-legume mixtures results in releasing the assimilated N by mineralisation of organic matter. In practice the mineralisation can only be controlled by means of soil cultivation. The aim of the present study is to analyse the relations between different intensities of soil cultivation and N-mineralisation. The data were used to test the simulation model CANDY. The field experiment of each 0.1 ha was set up at three sites in two different locations, which were cultivated from 1999 to 2001: Hohenheim (with trials 610 and 611) and Kleinhohenheim (with trial 660). In the beginning all sites had a three-year old grass-clover-alfalfa mixture, which was ploughed-in for trial 610 and 660 in the late summer of 1999 and in the year 2000 for trial 611. The factor soil tillage was varied in three stages as follows: RT+RT+plough: double rototill cultivation (RT, 10 cm deep) in intervals of approx. 2 weeks, followed by ploughing (plough, 25 cm deep); RT+plough: single rototill cultivation, followed by ploughing (depths as mentioned above); Plough: ploughing without any preceding cultivation (depth 25 cm). After uniform seedbed preparation with a rotary harrow, wheat was sown on all trial sites in autumn, and in trials 610 and 660 it was followed by oat in 2001. Nitrogen content in the soil was determined by repeated sampling at a depths of 0-10, 10-20, 20-30, 30-60 and 60-90 cm. Monitoring boxes were installed in 1 m depth in an undisturbed soil body from September 2000 until April 2001 to record nitrate leaching. Ploughing-in of the grass-clover-alfalfa by means of rototiller cultivation (treatments RT+RT+plough and RT+plough) was followed by a significant increase of mineralisation, which in case of the plough treatment was less pronounced. In this case the date of cultivation, 6 weeks after the rototilling, may have had an influence. Nmin-contents in autumn 1999 were higher after RT+RT+plough than after RT+plough. It has to be taken into consideration that there was a time gap between both treatments of 9 days. But also in the following year (611), when both treatments were cultivated the same date, there was a significant, slight difference of the Nmin values depending on the treatment. Nitrate leaching was only measured in trial 611. Quantities of 86, 84 and 64 kg N/ha were observed in treatments RT+RT+plough, RT+plough and plough, respectively during winter. Due to high Nmin-contents in autumn, for the rototill treatments higher nitrate losses can be assumed compared to the plough treatment for both years of experiment. Depending on the location, nitrogen uptake and yields of wheat turned out to be different. In Kleinhohenheim they were lower in treatments RT+RT+plough and RT+plough than in the plough treatment. It was the other way round in Hohenheim on a higher production level. Due to strong hail impact, this relation between the treatments was not to be proved in trial 611. Oat was the second crop. In this case no effects of intensity of soil cultivation on nitrogen uptake and yield could be observed between treatments and locations. The CANDY model was used for simulating the results of trials 610 and 611. First, the model seemed to be inadequate because it could not model the N-dynamic after soil cultivation. Adding fictitious organic material to the system helped to overcome this problem and then, on average, the N-dynamic model fit was satisfying. An estimate to overcome the general insufficient fit of the model could be mineralisation of parts of the physically protected organic matter (SOS), which is already implemented in the model, right at the moment of cultivation. Data of soil moisture of trial 611 served to calibrate the model successfully. With amended soil parameters the model was then easily applied to the corresponding data of trial 610. In contrast, CANDY did not predict well the nitrate leaching - possibly because the model did not consider preferential flow.
Evaluation of new open pollinating broccoli genotypes (Brassica oleracea convar. botrytis var. italica) specifically bred for organic farming conditions focusing on agronomic performance and glucosinolate content
(2018) Sahamishirazi, Samira; Graeff-Hönninger, Simone
Currently, a considerable share of varieties being used in the organic vegetable production are developed for conventional high-input production systems, and broccoli is no exception. In addition, F1 hybrids are cultivated in organic broccoli production to a great extent because of high quality and yield. Two main restrictions of cultivating the mentioned categories of varieties in organic farming are; 1) ban of using cytoplasmic male sterility (CMS) in organic agriculture for reproduction of F1 hybrids of broccoli and limitations of farmers to produce their own seeds, 2) absence of special traits of these varieties which result in weaker performance when being cultivated under organically low-input conditions. In contrast to hybrids, cultivation of open pollinating broccoli varieties gives the opportunity of reproducing seeds to organic farmers. Therefore, developing new open pollinating broccoli varieties, which have the same quality (agronomical, chemical and sensorial) as F1 hybrids, through organic breeding programs (on-farm breeding) would allow the organic broccoli farmers to replace the hybrids with varieties adapted to organic production conditions. With this in mind, the German Federal office for Agriculture and Food (BLE) initiated a project on “Breeding development of open pollinating cultivars of broccoli for organic farming in terms of agronomic characteristics, secondary and bioactive ingredients and sensory properties”. This was a joint project which was done through the cooperation of University of Hohenheim and Kultursaat e. V. (NGO of on-farm breeders) in two parts during six years (2011-2016). The present doctoral thesis, which was a part of the mentioned project, aims at 1) investigating the agronomic performance of the newly bred open pollinating genotypes of broccoli, 2) developing a Near-Infrared Spectroscopy (NIRS) method for fast analysis of total, indole, aliphatic and individual glucosinolates content of broccoli samples; and 3) determining the total and individual glucosinolate content of the newly bred open pollinating genotypes of broccoli. For investigations on agronomic performance, two field experiments were carried out by cultivating eleven newly bred open pollinating genotypes, two F1 hybrids and an open pollinating variety of broccoli over two growing seasons of fall 2015 and spring 2016. Evaluation of the effect of genotype, growing season and their interactions on agronomic parameters were targeted in this study. According to our findings, assessment of agronomic variables indicated that although there were distinctions in different parameters such as head firmness, head shape and total biomass fresh weight among the newly bred open pollinating genotypes, some genotypes performed similar to hybrid varieties in organic farming. However, most of the open pollinating genotypes had 16 % to 73 % lower yields compared to the hybrid varieties depending on growing season. Generally, the “marketable yield” of the genotypes was under the significant effect of “genotype × growing season interaction”. Head weight was significantly affected by growing season which resulted in significantly lower head weight of some genotypes in the spring compared to the fall season. Overall, cultivation of the genotypes in fall season led to significantly higher marketable yields, head weight and total biomass weight, as well as firmer heads in contrast to the spring season. Considering the performance of different agronomic parameters, we recommend genotypes “TH-CAN-SPB”, “Calinaro”, “CHE-GRE-G” for both fall and spring growing season. Other genotypes such as “CHE-GRE-A”, “CHE-BAL-A” and “CHE-MIC” and “Line 701” are also recommended for cultivation in spring growing season specifically due to the high marketable yield and share of marketable heads. In addition, this thesis aimed at testing a fast analytical technique for determination of glucosinolates content in order to help breeders to quickly test their most favorable genotypes during breeding procedures based on glucosinolates content. For this purpose, the accuracy of NIRS technic was tested, regardless of type of genotype, for fast analysis of the individual and total glucosinolates content of broccoli samples. NIRS calibration was developed by reference method of High Performance Liquid Chromatography (HPLC) based on modified partial least squares regression, to measure individual and total glucosinolates content of open pollinating genotypes of broccoli regardless of the type of genotype. The calibration was analyzed using coefficient of determination in prediction (R2) and ratio of preference of determination (RPD). Large variation occurred in the calibrations, R2 and RPD due to the variability of the samples. Derived calibrations for total glucosinolates (RPD = 1.36), aliphatic glucosinolates (RPD = 1.65), glucoraphanin (RPD = 1.63) and 4-methoxyglucobrassicin (RPD = 1.11) were quantitative with a high accuracy, while for indole glucosinolates (RPD = 0.95), glucosinigrin (RPD = 0.62), glucoiberin (RPD = 0.67), glucobrassicin (RPD = 0.81) and neoglucobrassicin (RPD = 0.56) they were more qualitative. Overall, the results showed a good potential of NIRS in determination of different glucosinolates in a large sample pool of broccoli quantitatively and qualitatively. The achieved calibration equations were used to measure glucosinolates content of the broccoli samples of following years. To evaluate the health beneficial value of the open pollinating genotypes, the glucosinolates content of them were determined. The determination was done by the tested NIRS technic. Six individual glucosinolates were detected in the broccoli samples similar to findings of the previous chapter. Glucoraphanin (1.44-1.69 µmol g-1 DW), glucobrassicin (0.63-0.77 µmol g-1 DW) and neoglucobrassicin (0.38-0.74 µmol g-1 DW) had the highest share and were the main individual glucosinolates. Total glucosinolates content ranged from 3.46 to 3.60 µmol g-1 DW across both growing season. Significant effect of genotype and growing season existed on the total glucosinolates content of broccoli samples. All individual glucosinolates were affected by genotype. The effect of growing season was significant on all individual glucosinolates, except for glucobrassicin. The interaction of genotype × growing season was significant on all indole glucosinolates, glucoraphanin and glucoiberin. Generally, the glucosinolates content of the samples were higher when broccoli genotypes were cultivated in the fall growing season, however the difference in the level of glucosinolates contents across seasons was significant only for glucoraphanin, neoglucobrassicin, 4-methoxyglucobrassicin and glucoiberin. The open pollinating genotypes showed a similar range of glucosinolates compared to the tested hybrids and performed as good as the hybrids. Since total glucosinolates were nearly similar in all open pollinating genotypes across seasons, all are recommended for cultivation in both growing seasons. It is important to note that this study only focused on a single health beneficial compound (glucosinolate) in broccoli heads. To provide a full insight into the nutritive and health benefiting compounds of broccoli such as vitamins and polyphenols, supplementary studies will have to be conducted. All in all, releasing new open pollinating broccoli varieties out of this pool of genotypes and replacing the present varieties with them seemed beneficial due to the well adapted agronomic performance and high health value with regard to glucosinolates content under organic farming conditions.
Highlighting outstanding beetroot varieties for the food industry - Evaluation of agronomic and compositional attributes of organically grown beetroot (Beta vulgaris L. subsp. vulgaris) varieties
(2022) Yasaminshirazi, Khadijeh; Graeff-Hönninger, Simone
The constant increase in awareness of the relationship between health and diet changed consumers’ perception of food and, accordingly, their food products’ choices. In this regard, the demand for foods, which promote mental and physical health and prevent specific diseases, has increased. Due to its high amount of bioactive compounds, which permits the reformulation of conventional products and transformation of them into functional foods, beetroot (Beta vulgaris L. subsp. vulgaris) was classified as a superfood. On account of the rising demand for organic food products, there is a necessity for varieties, which are adapted to the special requirements of organic farming. Alongside growing beetroot genotypes with desirable agronomic performances and promising contents of bioactive compounds, preserving the quality of harvested beetroots for an extended time can prolong the availability and use of this crop. Hence, affordable and easy-accessible possibilities for prolonging the shelf life of beetroot are required. This thesis aimed to disclose the genetic potential of a broad assortment of new and existing open-pollinated beetroot genotypes, which perform desirably in terms of agronomic and morphological traits (Publication I), compositional characteristics (Publication II), and quality stability (Publication III) under organic farming conditions. In this respect, in total, six genotype-screening field experiments were conducted in 2017 and 2018 at three different locations. Results of the first publication depicted a significant impact of genotype on the total and marketable yields, as well as most of the assessed morphological traits, including skin smoothness, corky surface, and beet shape uniformity. With the analysis of the contents of the total dry matter, total soluble sugar, nitrate, betalains, and total phenolic compounds in the second publication, significant differences were found between 15 studied beetroot genotypes. In addition, the outcome of the third publication demonstrated a significant effect of genotype on all measured compounds of 36 examined beetroot genotypes. Furthermore, the extent of change in the compositional quality during four months of cold storage was assessed for all studied genotypes. On account of the existing genetic variability in beetroot, it was concluded that the intended final utilization should be taken into account for the selection of suitable genotypes. In addition to the conducted assessments in Publication I – III, in the overall project framework from which this thesis was derived, the sensory characteristics of selected open-pollinated genotypes were compared with the commercially used varieties. Three sensory tests were carried out at the University of Hohenheim to determine consumers’ perception of the desired beetroot taste characteristics, including sweetness, aroma intensity, bitterness, earthy flavour, and the degree of acceptability. Generally seen, the studied open-pollinated genotypes indicated more sweetness and less bitterness compared to the F1 hybrid varieties. Furthermore, this thesis assessed the impact of nitrogen fertilisation level on selected compounds (nitrate and total soluble sugar contents) of specific genotypes (Borus, Ronjana, and Regulski Okragly) at the University of Hohenheim in 2018 and 2019. The outcomes indicated no significant influence of the N fertilisation rate on the total soluble sugar content. However, the impacts of fertilisation level and interactions between year and replication on the nitrate content were significant. Consequently, with adjusted N fertilisation, the amount of nitrate in beetroot can be directed in the desired direction based on the intended product (for example, sport drinks with high nitrate levels, and baby food with low nitrate levels). Nevertheless, in the pool of the investigated genotypes in Publication III, some genotypes possessed a comparable nitrate content with the highest values reached by using additional N-fertilisation in this experiment. To conclude, with the investigation of a broad assortment of beetroot genotypes, the findings of the present thesis revealed a high genetic variability regarding yield, morphological and compositional characteristics of beetroot, which provide new possibilities for farmers, the food industry, and consumers. To ensure the competency of the studied genotypes, further studies concerning the determination of other taste-relevant compounds like geosmin and disputable compounds such as oxalic acid are highly recommended. Moreover, to extend the use of the functional properties of fresh beetroot throughout the year, besides the selection of a suitable genotype, the external factors, such as storage conditions, should be optimized as well.
Pflanzenbauliche Untersuchungen zum ökologischen Anbau von Körnerleguminosen an sommertrockenen Standorten Südwestdeutschlands
(2007) Poetsch, Jens; Claupein, Wilhelm
Grain legumes, as nitrogen fixing crop, protein rich animal feed and marketable product are of great importance for organic agriculture. Due to staged abolition of the possibility to add non-organic products in organic animal feeding, the EU?s demand for organically produced protein feed is further increasing. Field bean (Vicia faba) and field pea (Pisum sativum) are large-scale crops but feature a limited feeding value. Lupin species (Lupinus spp.) excel by protein contents of up to 40% in the seed and higher protein value. At warmth favoured locations in southwestern Germany the valuable soybean (Glycine max) can be grown successfully and obtain above-average proceeds in natural food industry. Constraints of yield stability of grain legumes result amongst other things from frequently high weed infestation in organic cropping systems and suboptimal water supply at summer-dry locations. For lupins, moreover, particular soil requirements and the seed-borne fungal disease anthracnosis are problematic. Nitrogen residues after harvest are relevant for subsequent crop as well as groundwater protection. The presented work aimed at defining preconditions and developing cropping strategies to optimise yield stability and level of organically grown grain legumes with a main focus on summer-dry locations, to increase diversity of cultivatable crops and provide information on disposition of nitrogen residues. For this purpose from 2003 to 2005 trials at several locations as well as in greenhouse and laboratory were accomplished. Field trials on organic weed control in soybean as well as white and narrow-leafed lupin (Lupinus albus und L. angustifolius) were conducted at organically managed commercial sites in the upper rhine valley. At the same time agronomic measures for optimisation of competitiveness and machinery implementation were varied. Early high soil coverage and crop height contributed considerably to grain legumes? competitiveness. Delayed sowing at elevated temperatures supported rapid juvenile development and allowed for pre-sowing weed control. At optimum sowing date these effects may be used without yield depression or maturity problems. Reduced row distance was beneficial for optimum space utilisation and early crop closure, but effectiveness of mechanical means was highest at high row distance and large areal proportion for interrow cultivation. As an optimum compromise for grain legumes row distances of 30 - 35 cm are recommended. Optimum impact of mechanical means against weeds was achieved by combining interrow cultivation with harrow or fingerweeder. Forgoing interrow cultivation may be considered in strongly competitive crops like field bean. Lupin species appeared rather poor in competitiveness compared to other crops. Field trials on effects of cultivar and cropping strategy on overwintering and yield performance of autumn-sown field bean, field pea and white lupin were conducted at three locations. Summer drought caused substantial yield advantages of autumn-sown compared to spring-sown cultivars due to superior water supply at earlier flowering. With sufficient water supply a head start was not yield effective. Differing coincidence with pests and diseases could account for advantages (head start on aphid infestation) or disadvantages (fungal infections during winter period) of autumn-sown cultivars. Overwintering was excellent for winter field bean and good for winter field pea. For winter white lupin further trials are required. Temperatures down to -12°C were well endured by all of the three crops. The most important cropping parameter was the sowing date. Winter field bean permitted a relatively wide sowing window. Winter white lupin required strong development before winter and preferably early sowing. Sowing date of winter field pea presented an optimisation problem, because sowing too early leads to overdevelopment and reduced cold-tolerance, while sowing too late may reduce yield potential. Optimum sowing dates for southwestern Germany according to experimental results are in the range of early September (winter white lupin), mid-October (winter field bean) and late October (winter field pea). Water use efficiency may gain significantly in importance in the future. A two-year trial on cultivation prospects and yield performance of the notably drought tolerant chickpea (Cicer arietinum) in the upper rhine valley resulted in successful crop development, but problems with empty pods and inadequate grain quality. Further trials are considered promising. A field trial with white and narrow-leafed lupin confirmed that anthracnosis of lupin spreads less rapidly and yield effectively at summer-dry locations, and narrow-leafed lupin frequently stays unaffected. Laboratory studies for optimising detection methodology of the causative organism Colletotrichum lupini showed advantages of using sectioned petri dishes (quad plates), which confined propagation of disturbing organisms. A trial on seed storage under different temperatures, seed moisture contents and CO2-atmosphere produced no distinct treatment effect, but could confirm the general decrease of seed infection by storage. According to literature hot air (approx. 4 days at 65°C) also reduces seed infection effectively. Thus, storage or hot air treatment of basic seed and propagation at summer-dry locations appear as a viable over-all strategy. Difficult soil requirements of white and narrow-leafed lupin were studied by a pot trial as well as a comprehensive literature analysis. It is concluded that the so-called lime chlorosis is caused by HCO3--induced inactivation of physiologically relevant Fe(II) in the plant. Accumulation of HCO3- is basically caused by insufficient soil aeration and promoted by the presence of lime in the clay fraction. Furthermore, especially in narrow-leafed lupin, disturbances of root development are caused by high Ca-content or high and at the same time strongly buffered pH of soil solution. These conditions are often but not necessarily caused by lime. Analyses of harvest residues and soil were consulted for estimation of nitrogen dynamics. Immobilisation due to degradation of residues with high C:N ratio as well as uptake by catch crops contributed substantially to nitrogen conservation. Risk of leaching is predominantly site dependent. The over-all nitrogen balance of grain legumes when exporting the seed may be low or even negative. In conclusion, results of the presented work indicate that site adapted cropping systems with agronomic measures in the areas of crop rotation, choice of cultivar, sowing date or space allocation can still contribute considerably to yield stability in organic cultivation of grain legumes.
Phosphorus bioavailability of fertilizers recycled from sewage sludge and their suitability for organic crop production
(2020) Wollmann, Iris; Möller, Kurt
Phosphorus (P) nutrition of plants is a key production factor in agriculture. In an approach to recycle P from urban areas back to agriculture, technologies have been developed to produce mineral P fertilizers out of municipal sewage sludge. In this study, different P fertilizers recycled from sewage sludge have been investigated in pot and field experiments for their bioavailability to maize and several plant species of a crop rotation. It was also investigated, if bioavailability of recycled P fertilizers can be enhanced either by a soil inoculation with different bacteria strains that are efficient in P solubilizing, or by a cultivation of red clover in the crop rotation. As there is a lack of bioavailable P fertilizers in organic cropping systems, P fertilizers recycled from sewage sludge were evaluated for their suitability to be used in organic crop production. It has been shown that most of the investigated fertilizers recycled from sewage sludge have a higher P bioavailability than Phosphate Rock (PR). Fertilizer efficacy seems very dependent from specific production conditions which are decisive for the final product. Among the tested fertilizers, struvite (MgNH4PO4 . 6 H2O) was most efficient in increasing plant P offtake of maize (+ 27.5% in the field, and more than sixfold in a pot experiment, compared to the unfertilized control). Struvite and calcined sewage sludge ash (SSA) are efficient fertilizers at both acidic and neutral soil pH. Other fertilizers (e.g. untreated incineration ashes) have low solubility at soil with pH > 6, and thus, might be used on acidic soil only, or as raw material for fertilizer production. In the field experiment, the overall response to P fertilizer input was low, which probably can be attributed to a sufficient inherent P supply on the used site. An immobilization of fertilizer P over time could be shown in all experiments. Thus, recycled P fertilizers should be applied to responsive crops in the rotation. An improved P supply of maize could be shown when grown after red clover in the crop rotation. This might be attributed to a combination of different factors, such as a solubilization of sparingly soluble P forms in recycled fertilizers, following a drop in soil pH due to biological N2 fixation of clover. A recycling of P to maize via decomposed clover roots might in addition have contributed to an increased P supply of the subsequent maize. Despite this promising effect, P mobilization by clover cultivation was not sufficient to cover the entire P demand of maize. Thus, additional fertilizer P inputs to maize might still be necessary to ensure optimal plant growth on P deficient soils. With one exception, an application of different bacteria strains generally did not affect P supply of the plants. Applied bacteria seem very dependent on the environmental conditions. It is conceivable, that especially in organic systems, a soil application with external bacteria does not enhance the beneficial effects of a high microbial abundance and activity which often is already present in organic cropping systems. From an agronomic point of view, P fertilizers recycled from sewage sludge are better alternatives for organic crop production than PR. A recycling of nutrients generally fits well with basic organic principles. By introducing those fertilizers, the organic system could make a decisive contribution to the ongoing effort of closing the P cycle, and, once more, develop towards a farming system of the future.
Spatial econometric methods in agricultural economics : selected case studies in German agriculture
(2013) Schmidtner, Eva; Dabbert, Stephan
The location of agricultural activities is determined by location factors that are spatially heterogeneous, such as climate and soil; for the spatial distribution of some agricultural specialties, spatial dependence, i.e., beneficial and self-enhancing effects resulting from a concentration of these agricultural activities, might also play a role. Thus, the dimension ?space? might be of importance in analysing agricultural research settings. This cumulative dissertation consists of three articles addressing current research questions on the spatial distribution of agricultural activities and agricultural profitability in Germany. To account for the geographic location of attributes, spatial econometric analysis tools are used. The first article addresses the determinants of the uneven spatial distribution of organic farming in Germany. In addition to traditional location factors, positive agglomeration effects might also influence the spatially heterogeneous concentration of organic agriculture. Conventional farmers might be more likely to convert to organic farming given an easy communication with organic farmers located nearby and a geographically close and strong institutional network. First, a theoretical model explaining the decision of a farmer to convert from conventional to organic agriculture is established. Next, secondary data at the German county level are analysed by using spatial lag models. Data on organic farming refer to the year 2007. The results suggest that agglomeration effects matter in organic agriculture. For the previous analysis, aggregated data at a relatively low spatial resolution are used, which might lead to results that are artificially generated through the process of data aggregation. The second article addresses the question whether results can be confirmed at different spatial levels, assuming that agglomeration effects are important in organic farming. The results of spatial lag models are compared at two measurement scales, the German counties and community associations. Secondary data are also used in this analysis; for the organic sector, 2007 data are considered. The analysis indicates that essential factors determining the decision to convert from conventional to organic farming are sustained at different spatial resolutions. The results at the lower spatial resolution are shown to be not artificially generated through the aggregation process in this case, which strengthens the relevance of the previous study. The third publication assesses the effects of different indicators of soil characteristics on the estimation results of a Ricardian analysis. The study draws on data from the official farm census conducted in 1999 and on weather data from the German National Meteorological Service at the county level for the time period 1961-1990. Additionally, different soil data bases are considered to control for soil quality. The results of spatial error models suggest that rental prices are determined by climate and non-climate factors. Accounting for different methods of measuring soil quality does not influence the results of the analysis. To estimate the effects of changing climatic conditions on future land rents, data from the regional climate model REMO for the time period 2011-2040 are used. The models show that projected climate levels will have an overall positive but spatially heterogeneous effect on the income from agriculture in Germany. The empirical analyses presented illustrate that spatial econometrics can offer appropriate tools for analysing agriculture. In all three cases theoretical considerations and diagnostic tests for spatial dependence suggest using spatial analysis techniques. The use of alternative specifications of the spatial neighbourhood matrix further supports the stability of results. The general approach and methods used could be translated to other issues in agricultural economics such as potential agglomeration effects in hog production or the future impact of climatic factors on the spatial distribution of viticulture. Thus, spatial econometrics might offer an interesting approach to various spatial research questions in agricultural economics, in addition to the applications that were selected for this thesis.
Suitability of conventional flowering fields and organic lentil mixed-crops to promote biodiversity on arable land
(2020) Gayer, Christoph; Dieterich, Martin
The rapid agricultural intensification during the last decades is among the main drivers of the dramatic and ongoing biodiversity loss on earth. The decline of species diversity and associated ecosystem services due to highly intensified farming practices and structural simplified agricultural landscapes includes the reduction of species richness and abundance of species. The loss of species and related shifts in species communities can also lead to altered functional traits within species communities. It can also include deteriorated population developments of single species known to be important ecosystem service suppliers for agricultural production. In Europe, billions of euros are spent each year to support farmers for applying environmentally friendly practices, but so far biodiversity continues to decline. This calls for the development of more effective biodiversity conservation measures on agricultural land. Within the framework of agri-environmental measures, agronomically non-productive measures exist such as the establishment of flowering fields, but there are also production integrated measures such as the organic farming of crops. Further, the growing of flowering lentil mixed-crops could be a valuable, but rarely studied option to further increase the biodiversity benefits of organic farming systems. Up to that, little is known about the relative effectiveness of non-productive flowering fields under conventional management and organically farmed mono- as well as lentil mixed-crops for the promotion of biodiversity on arable land. Within the scope of this thesis, i studied biodiversity effects in response to the establishment of annual flowering fields under conventional management, organically managed winter spelt as well as organic lentil mixed-crops. These three crop-use types were compared to conventional winter wheat (control). Besides, I took into account biodiversity effects of the within-field position (field edge versus interior) as well as the surrounding landscape complexity in 500 m around each study field. To get a comprehensive overview about potential biodiversity effects and related ecosystem functions in response to the four crop-use types, I assessed the abundance, species richness and community composition of wild plants (primary producers), carabids and spiders (ground-dwelling predators) as well as butterflies and wild bees (flower-visiting arthropods). I further assessed the functional diversity of carabids as an important species group for biological pest control. To quantify functional diversity in comparison between the four crop-use types, I used the community weighted means and functional divergence of three ecological traits – body size, feeding type, and flight ability. These traits can affect mobility (body size, flight ability) as well as pest and weed seed predation (feeding type, body size) of carabids. Last, I measured the population development of colonies of Bombus terrestris, I observed weight gain, foraging activity, worker body size, queen brood cell number and stored pollen types of colonies exposed at each study field in 2018. I found clear taxon-specific effects of the total abundance and species richness in response to the studied crop-use types. No distinct differences were found for the community composition, which was similar between crop-use types. Arable wild plants benefited most strongly from organic farming, in particular from lentil mixed-crops, but also from field edges. Ground-dwelling arthropods were also mainly promoted by field edges, whereas flower-visiting arthropods solely benefited from conventional flowering fields and organic lentil mixed-crops. Carabid functional diversity was higher at the field edge than the interior irrespectively of crop-use type. Feeding type diversity (carnivorous, ominovorous, herbivorous) of carabid assemblages did also profit from conventional flowering fields and organic winter spelt. Colonies of Bombus terrestries had higher foraging activity and larger body sizes, if exposed at organic winter spelt fields, whereas weight gain and queen brood cell numbers were unaffected by local crop-use type. Pollen stores within the colonies were dominated by Phacelia (Phacelia tanacetifolia) irrespectively of crop-use type. Phacelia was part of the sown seed-mixture in flowering fields, indicating a landscape-wide attraction of flowering fields as pollen source for Bombus terrestris. Over all studies i found only minor effects of the surrounding landscape, except the negative correlation between flower cover and pollen diversity of Bombus terrestris colonies. In summary, this thesis revealed that the establishing of annual flowering fields can be an appropriate measure to enhance biodiversity in conventional farming systems. Organic lentil mixed-crops are appropriate to further increase biodiversity benefits of organic farming systems. Within the conducted studies, different crop-use types promoted specific species groups and thereby different components of biodiversity. Hence, the results of this thesis reveal, that there is no single best measure for the promotion of biodiversity on arable land. Instead, the additive effects of non-productive and productive measures as well as field edge habitats underline, that a mosaic of different types of measures hold the greatest potential to benefit overall biodiversity in agricultural landscapes. Therefore, future agri-environmental schemes should provide particular incentives for individual farmers to apply a diversity of different measures on their farmland and should foster the collaboration and spatially coordinated implementation of complementary biodiversity measures between multiple farmers at the landscape scale.
Zweinutzungshuhn – was ist das? Umfrage unter Landwirt*innen und Geflügelhalter*innen in Deutschland 2022
(2023) Gebhardt, Beate; Bermejo, Gabriela; Imort-Just, Annik; Kiefer, Lukas; Zikeli, Sabine; Hess, Sebastian
To comply with the ban on chick culling that has been in effect since January 2022, the Federal Ministry of Food and Agriculture proposes three alternatives, including the hatching of dual-purpose chickens. In addition to the breeding and economic challenges of establishing dual-purpose animals in the value chain, the inconsistent understanding of what a dual-purpose chicken actually is and how its characteristics can be successfully communicated to consumers are seen as challenges. The goal of this working report is to present what a dual-purpose chicken is and what understanding farmers have of it. The German nationwide online survey among farmers and poultry farmers regarding the understanding and future of dual-purpose chickens was conducted in autumn 2022 as part of the EIP-Agri project "ZweiWert." The EIP project titled "Building Value Chains for Dual-Purpose Chickens in Baden-Württemberg" (ZweiWert) is funded by the Ministry of Food, Rural Areas and Consumer Protection of Baden-Württemberg from 01/2022 to 12/2024. Project partners include the Naturland Association of Baden-Württemberg, several departments of the University of Hohenheim, and many partners from agricultural production and marketing.