Die chronologische Liste zeigt aktuelle Veröffentlichungen aus dem Forschungsbetrieb der Hochschule Weihenstephan-Triesdorf. Zuständig ist das Zentrum für Forschung und Wissenstransfer (ZFW).
BackgroundUsing secondary phosphorus (P) sources recovered from waste streams for base fertilization of soilless growing media may help conserve the global phosphate resources. However, little is known regarding the plant availability of P from secondary sources for soilless plant production.AimThe objective of this study was to investigate the plant availability of P from secondary sources using a peat-based growing medium and standard extraction methods.MethodsSeventeen secondary P sources differing in terms of feedstock and processing were tested, and their fertilization efficacy was compared with that of water-soluble monocalcium phosphate (MCP-P) in a pot experiment using marigolds. The correlation of plant P uptake with calcium chloride + diethylenetriaminepentaacetate (CAT) and/or calcium–acetate–lactate (CAL) extractable P amount in the growing medium (PCAT and PCAL, respectively) was examined.ResultsOnly three of the 17 tested secondary P sources (all struvite forms) exhibited comparable fertilization efficacy to MCP-P. The remaining sources showed P uptake varying between 4% and 91% of MCP-P. For precipitates from liquid waste streams and untreated organic waste, except for sewage sludge and compost, the P uptake ranged from 71% to 100%. The highest variability (4%–86%) was observed for thermally and thermochemically treated secondary P sources. Plant P uptake was closely correlated with PCAT (R2 = 0.76) and PCAL (R2 = 0.78), and this correlation became even stronger when PCAT and PCAL were combined (R2 = 0.89).ConclusionsMost struvite forms meet the requirements of base P fertilization for soilless plant production and can substitute water-soluble fertilizers obtained from primary P sources. The combination of PCAT and PCAL may be a promising approach to characterize the plant availability of P from secondary sources in soilless growing media and warrants further consideration.
Due to the depletion of global phosphorus deposits and stricter legal regulations regarding phosphorus loads in wastewater, the recovery of phosphorus from wastewater is gaining more and more interest. There are plenty of techniques to recover phosphorus from wastewater and sewage sludge. Depending on the recovery technique and the subsequent processing, the availability of phosphorus to plants can differ widely. However, beside the chemical characteristics also grain size of the fertilizer, as is well known from rock phosphates, might be essential for plant availability. Thus, the plant availability of phosphorus in three wastewater-based fertilizers - sewage sludge ash (SSA), Mephrec and struvite - in relation to their grain size was evaluated in a pot trial with marigold. Recycled P fertilizers were applied to a peat based growing medium on basis of 30 mg P per pot (1) as received and (2) after grinding to a fine powder with a disc mill. For comparison, rock phosphate (Hyperphos) was treated in the same way and water soluble mono calcium phosphate (CaP) was used as benchmark. Marigold seedlings were pricked in 10-cm pots and cultivated for seven weeks according to common horticultural practice in a glass-sheltered greenhouse. With exception for finely ground struvite, P uptake of plants from the recycled fertilizers was significantly less than from CaP. However, P uptake from coarse struvite and powdered SSA was at least 50% of P uptake from CaP, whereas it was less than 5% for the remaining treatments. For all three recycled fertilizers as well as for the used rock phosphate grinding significantly increased P uptake, but only for SSA the effect was of practical relevance. The results reveal that grinding can improve the plant availability of phosphorus in recycled fertilizers, but the effect strongly depends on the chemical characteristic of the product.
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Dr. Dieter Lohr,
Ronja Fritzsche,
Prof. Dr. Elke Meinken
Dr. Dieter Lohr,
Johannes Görl,
Prof. Dr. Elke Meinken
Nitrogen dynamics of chopped hop bines - Effect of leaf to stem ratio (2021) 4th International Symposium on Horticulture in Europe, 09.-11.03.2021, virtual .
Johannes Görl,
Dr. Dieter Lohr,
Prof. Dr. Elke Meinken
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