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We aimed at determining the effect of feedstock composition on P content and availability in compost when small-scale on-farm composting was applied. The research is based on two compost experiments with 3 treatments each.
In the first compost trial, several feedstock materials were compared for composting with 7.5-10 vol% of fresh chicken manure. The tested feedstock materials were wheat straw, grass clippings, poplar bark, compost and grass hay. Based on chemical characteristics, the compost with 42.5 vol% bark in the feedstock had the highest quality as soil improver.
In the second trial, the effect of the amount of chicken manure in the feedstock mixture was assessed, i.e. 10, 17 or 20 vol%. The tested feedstock materials were wheat straw, grass clippings, poplar bark, willow wood chips, and grass hay. Due to dry weather conditions, intensive follow-up of the process (e.g. regular moistening) was necessary. The second composting experiment was characterized by high temperatures over a long period, indicating that the applied feedstock mixture served as a long-term C source for the process. Results from the second composting experiment indicate that 10 vol% of fresh chicken manure is the upper limit for reducing nutrient losses and achieving a fertilizer with a sufficiently high N/P ratio.
In general, compost characteristics varied due to differences in feedstock characteristics and progress of the composting process. Besides general characteristics, cell wall components and total and plant-available P and N concentrations were measured in the composts. Availability of P was assessed in ammonium acetate extracts at pH 4.65, and in extracts of 0.25 M NaOH and 0.05 M Na2-EDTA. Based on the analysis of cell wall components of the feedstock mixture and the composts, the biodegradation potential was calculated for each of the composts.
One compost from each compost trial 1 and 2 was selected for application in the field. A field trial with leek was set up to assess the P release from composts based on poultry manure, pure poultry manure and other organic fertilizers, of which some were based on manures as well.
Preliminary conclusions are that poultry manure can be recycled through composting in an organic fertilizer with optimal nutrient ratio and organic matter content. P in the poultry manure can thus be recycled when appropriate feedstock materials are selected and the amount of fresh manure is restricted.
|Titel||Conference Proceedings of the International Conference ORBIT2012|
|Pagina's||Topic 7, 71-76|
|ISBN van elektronische versie||ISBN 3-935974-36-1|
|Status||Gepubliceerd - 2012|
|Evenement||ORBIT2012 - Rennes, Frankrijk|
Duur: 12-jun-2012 → 14-jun-2012