Abstract The fertilization with organic amendments and digestates from biogas plants is increasingly used to increase carbon stock and to improve the soil quality, but little is still known about their long‐term effects. A common method to analyse organic amendments and their mineralization is incubation experiments, where amendments get incubated with soil while CO 2 release is measured over time. In a previous study, carbon models have been applied to model the carbon dynamics of incubation experiments. The derived parameters describing the carbon turnover of the CCB model (CANDY Carbon Balance) are used to simulate the SOC and SON dynamics of a long‐term field trial. The trial was conducted in Berge (Germany) where organic amendments like slurry, farmyard manure or digestates were systematically applied. To grant a higher model flexibility, the amounts of crop residues were calculated for roots and stubble separately. Furthermore, the mineralization dynamics of roots and stubble are considered by the model parameters for each crop. The model performance is compared when using the dry matter and carbon content received from the field trial and the incubation experiments, to evaluate the transferability. The results show that the incubation parameters are transferable to the field site, with rRMSE < 10% for the modelled SOC and rRMSE between 10% and 15% for the SON dynamics. This approach can help to analyse long‐term effects of unexplored and unusual organic fertilizers under field conditions, whereat the model is used to upscale the C dynamics from incubation experiments, considering environmental conditions.
In 403 elderly people residing in their own homes a dietary interview was undertaken with special reference to the intakes of vitamins and minerals. The group was randomly selected. The data were compared with the Recommended Dietary Allowances, Joint Nordic Recommendations and the absolute minimal necessary amounts. Intakes of folacin was low in 100% of the interviewed, intakes of cholecalciferol was low in 62% and in 83% intakes of pyridoxine was low as compared to the recommendations. The majority had sufficient amounts of ascorbic acid, thiamine, riboflavin, retinol and cobalamin from the diet. The intake of zinc was low in 87% of the interviewed, but risk of zinc deficiency might only be present in 0.5%. The intakes of iron and calcium was judged to be sufficient. The physiological needs of the elderly may, however, vary from the standards used here and recommendations with special reference to the elderly are in request. The conclusion is that the diet of the elderly, possibly with exception of folacin, is well above their absolute minimal requirements, but the margin towards malnutrition is small. This means that elderly people should be considered a vulnerable group with respect to the intakes of vitamins and minerals.
Fermentation in combination with subsequent composting of biowaste is a preferred method for municipalities to recycle organic byproducts and transform them into useful end products for soil amelioration or plant fertilization. These compost products, especially if obtained from household wastes, can be a source of hazardous components, e.g. heavy metals, pathogens, synthetic chemicals or toxic organic compounds. An avoidance test with two earthworm species (Eisenia fetida and Aporrectodea caliginosa) was conducted to assess the impact of differently processed biowaste based digestate products on soil invertebrates. Body weight changes were recorded, as well as differences in effects on adult versus juvenile earthworms.While E. fetida showed no avoidance towards the digestate products (negative avoidance, meaning that the tested products were preferred, of 80 to 100 %), A. caliginosa rejected the crude biowaste digestate compost in higher concentrations (avoidance of 45 %), but not the agglomerated or pelletized variants. A clear weight gain of up to 25 % was observed only for individuals of E. fetida. The developmental stages of the worms were not crucial for the outcome of the avoidance test.Based on the results of this study the application of biowaste products on arable land cannot be recommended without constraints.
Abstract Phosphorus is a nonrenewable resource, which is required for crop growth and to maintain high yields. The soil P cycle is very complex, and new model approaches can lead to a better understanding of those processes and further guide to research gaps. The objective of this study was to present a P‐submodel, which has been integrated in the existing Carbon Candy Balance (CCB) model that already comprises a C and N module. The P‐module is linked to the C mineralization and the associated C‐pools via the C/P ratio of fresh organic material. Besides the organic P cycling, the module implies a plant‐available P‐pool (P av ), which is in a dynamic equilibrium with the nonavailable P‐pool (P na ) that comprises the strongly sorbed and occluded P fraction. The model performance was tested and evaluated on four long‐term field experiments with mineral P fertilization, farmyard manure as organic fertilizer and control plots without fertilization. The C dynamics and the P av dynamics were modelled with overall good results. The relative RMSE for the C was below 10% for all treatments, while the relative RMSE for P av was below 15% for most treatments. To accommodate for the rather small variety of available P‐models, the presented CNP‐model is designed for agricultural field sites with a relatively low data input, namely air temperature, precipitation, soil properties, yields and management practices. The CNP‐model offers a low entry threshold model approach to predict the C‐N and now the P dynamics of agricultural soils.
Abstract Organic amendments are important to sustain soil organic matter (SOM) and soil functions in agricultural soils. Information about the contribution of organic amendments to SOM can be derived from incubation experiments. In this study, data from 72 incubated organic amendments including plant residues, digestates and manure were analysed. The incubation data was compiled from three experimental setups with varying incubation times, soils and incubation temperatures, in which CO 2 release was measured continuously. The analysis of the incubation data was performed with an approach relying on conceptual parts of C‐TOOL, CCB, Century, ICBM, RothC and Yasso which are all well‐approved first‐order carbon models that differ in structure and abstraction level. All models are an approximation of reality, whereby each model differs in understanding of the processes involved in soil carbon dynamics. To accumulate the advantages from each model a model ensemble was performed for each substrate. With the ability of each carbon model to compute the distribution of carbon into specific SOM pools a new approach for evaluating organic amendments in terms of humus building efficiency is presented that, depends on the weighted model fit of each ensemble member. Depending on the organic substrate added to the soil, the time course of CO 2 release in the incubation studies was predicted with different accuracy by the individual model concepts. Averaging the output of the individual models leads to more robust prediction of SOM dynamics. The E HUM value is easy to interpret and the results are in accordance with the literature.
Digestates are commonly used as organic inputs in agriculture. This study aimed to answer four questions: (1) What are the immediate and longer-term impacts of digestates on soil microbial activity?; (2) How much of the digestates’ carbon is mineralized within the first months? (3) How do the nitrogen, lignin, cellulose, and hemicellulose contents of digestates influence microbial activity and carbon mineralization? (4) How does the soil type influence mineralization? To investigate this, dehydrogenase activity (DHA) was measured in a field trial and in laboratory experiments with five digestates (DGs), cattle slurry, and cattle manure. DHA measurements were supplemented with soil respiration experiments using two different soils. DHA was significantly increased by all organic inputs, but decreased back to the control level within seven months under field conditions. Twenty percent to 44% of the organic carbon (Corg) in the digestates was converted to CO2 after 178 days. Soil respiration was significantly negatively correlated to lignin content (r = −0.82, p < 0.01) and not correlated to nitrogen, cellulose, or hemicellulose content. On the basis of equal carbon application, slurry promoted soil respiration and DHA more strongly than digestates in the short term.
Depending on the quality of the input substrates, process parameters, and postfermentation treatments, digestates may contain a broad spectrum of potentially toxic elements. We suspected that these contents may vary on a broad scale even under seemingly stable process conditions at the biogas plant. Digestates from four biogas plants were therefore continuously analyzed for their contents of phosphorus, nitrogen, cadmium, copper, lead, and zinc over a period of six years. The input substrates varied between the plants (e.g., cattle and pig slurry and rye and maize silage), but were the same for each plant over the whole period. The N : P ratio of the digestates ranged from 2 to 24, with the digestate coming from cofermentation of pig slurry and energy crops (“DG Pig”) having the widest range of N : P ratio over the years. Heavy metal loads of all digestates and during all evaluations did not exceed the limits set by European or German legislation, but as previously expected, showed a large variability especially if cattle or pig manure were used as substrates. Copper content of Cattle slurry before digestion was 897.7 mg kg −1 DM in one case, and zinc content of DG Pig reached 590.2 mg kg −1 DM also once during the investigation. As a result, we strongly recommend to monitor especially phosphorus, copper, and zinc contents in digestates very closely and in short intervals.
Both Joseph Conrad's novella Heart of Darkness and Francis Ford Coppola's film Apocalypse Now are regarded as outstanding works in their respective field of art. Their reputation rests partly on their artistic value and partly on their preoccupation with topics which were highly relevant at the time of their publication/release. They are for the most part regarded as independent works of art and the differences in the spatio-temporal setting and in the type of adventure easily hide the fact that Apocalypse Now is based on Heart of Darkness. The fact that both works differ to a very high degree from each other makes them suitable for examining the borderline between adaptation and intertextual reference. By comparing them from a narratological and an ideological point of view this thesis aims however to conclude that the influence of Heart of Darkness on Apocalypse Now classifies the relationship between them as an adaptation.
