@inproceedings{WatsonRummelBeuleetal., author = {Watson, Conor and Rummel, Pauline and Beule, Lukas and Schl{\"o}sser, Charlotte and Hemkemeyer, Michael and Schwalb, Sanja and Preißing, Timo and V{\"o}gerl, Jakob and Wichern, Florian}, title = {Excellent excrement? The potential benefits and drawbacks of soil amendment with frass}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:1383-opus4-17689}, abstract = {Insect rearing is a rapidly growing sector in Europe, with larval protein production projected to exceed 1 Mt in 2025. The by-product frass is a mix of larval faeces, exoskeletons and undigested substrate. Given its potential as a soil improver, frass could make insect production a "zero waste" industry. However, its positive reputation has not been thoroughly scrutinized with regard to environmental impacts. We therefore conducted experiments to investigate the effects of frass application on the soil microbial community, release of greenhouse gases and heavy metal availability. The main conclusions were: 1) Frass is nutritious and can benefit the soil microbial biomass, but rapid loss of C and N reduces its fertiliser and organic amendment potential 2) Co-application of frass with urease inhibitors could allow it to be utilised as a slow-release N fertiliser 3) Concurrent soil amendment of frass with nitrification inhibitors prevents soil nitrite accumulation 4) All frass types tested are suitable as ameliorative amendments to heavy-metal contaminated soils}, language = {en} } @masterthesis{Voegerl, type = {Bachelor Thesis}, author = {V{\"o}gerl, Jakob}, title = {Assessing the effect of N-fertilisation on biomass development and plant interactions in the ancient Milpa compared to pure stands and its potential to reduce fertiliser inputs in traditional small-scale farming}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:1383-opus4-6214}, school = {Hochschule Rhein-Waal}, pages = {55}, abstract = {Over the past years, nitrogen (N) fertilisation has been identified as an issue that has a major negative impact on the environment. Therefore, sustainable agricultural practices aim to reduce external fertiliser inputs and focus more on naturally available resources and sustainable cropping practices. One example of that is the ancient milpa polyculture which is practised by traditional small-scale farmers in Central America. It consists of climbing bean (Phaseolus vulgaris var. vulgaris), maize (Zea mays), and squash (Cucurbita moschata) that are said to represent a holistic symbiosis in which beans assume the task to accumulate additional nitrogen via N2-fixation and subsequently transfer it to its companions. The potential of intercropping, and thus nitrogen transfer to level out and reduce nitrogen fertiliser inputs compared to monocultures has not been assessed yet and little is known about the resulting practical implementation for small-scale farmers. Therefore, a pot trial with monoculture treatments (100 kg N/ha) of each crop and milpa treatments with varying levels of nitrogen fertilisation (0, 25, 50, 75, and 100 kg N/ha) was established. The intercropped beans were labelled with the 15N isotope using the cotton wick method to track nitrogen transfer in the system. Further, the Land Equivalent Ratio (LER) was used to determine the productivity of the system. Results showed that all polyculture treatments performed similarly or significantly better than the pure stands in terms of total dry matter content per pot. Milpas provided with 100 and 25\% of the recommended nitrogen rate were most productive and achieved a total LER of 1.25 and 1.30, respectively. Also, the non-fertilised milpa was still as productive as the respective plants grown in a monoculture. Due to external reasons, the importance of nitrogen transfer and the related microorganisms could not be evaluated. However, growing a milpa instead of monocultures enables farmers to greatly reduce N fertiliser inputs and provides higher yields in the growing season, while other intercropping benefits are also present. It further has the potential to maintain yields and enhance natural nutrient cycling even if no fertiliser is applied.}, language = {en} }