Composting for increasing the fertilizer value of chicken manure: effects of feedstock on P availability

Bart Vandecasteele, Bert Reubens, Koen Willekens, Annelies Beeckman, Lieven Delanote, Stefaan De Neve

    Onderzoeksoutput: Hoofdstuk in Boek/Rapport/CongresprocedureC1: Artikels in proceedings van wetenschappelijke congressen, die niet inbegrepen zijn in A1, A2, A3 of P1

    Uittreksel

    Soils in Northern Belgium under agricultural use are low in organic carbon. Application of compost as a source of stabilized organic matter is one strategy for maintaining or increasing the soil organic carbon content. Compost for this purpose can be prepared at the farm level, giving the farmer the opportunity to recycle organic wastes. To meet fertilization standards to reduce nutrient leaching, especially the total P content of the composts limits the application rate. Use of poultry manure as organic fertilizer is restricted due to its low N/P ratio. For some types of manure, adding woody material or straw allows to process the manure to a high quality compost. Including chicken manure in compost may result in a stable product rich in nutrients and organic matter, with a higher C/P value. This research was set up to find out optimal feedstock composition for composting poultry manure at the farm in order to create a soil improver with a higher value as organic fertilizer.
    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.
    TaalEngels
    TitelConference Proceedings of the International Conference ORBIT2012
    Aantal pagina's6
    Datum2012
    Pagina'sTopic 7, 71-76
    ISBN van elektronische versieISBN 3-935974-36-1
    StatusGepubliceerd - 2012
    EvenementORBIT2012 - Rennes, Frankrijk
    Duur: 12-jun-201214-jun-2012

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