Journal of the Society of Agricultural Structures, Japan

The bulk density values were examined for mixtures in which swine manure was mixed with sawdust, rice husks, and returned swine manure compost as supplementary materials. The mass per unit area and the bulk density up to a deposition height of 2 m were estimated from initial bulk density and the regression equation of the settlement rate of the load test using a small vessel. The initial bulk densities of the mixtures were lower in the saw dust mixture and higher in the returned compost mixture than in previous studies. The amount of subsidence was larger when the moisture content was higher in the sawdust mixture, however the relationship with the moisture content was unclear in the rice husk mixture and the returned compost mixture, and the difference due to the supplementary materials was also small. The obtained bulk density values were about 60 to 70 % for the rice husk mixture, 80 to 90 % for the rice husk mixture, and 110 to 120 % for the returned compost mixture than the previous values. These differences were caused by the different dry mass ratios of swine manure and supplementary materials and the different properties of the supplementary materials, so the influence of the changes in the properties of swine manure was considered to be small.

View full abstract

Show abstractHide abstract

The bulk density values of compost mixtures made by mixing dairy cow manure with saw dust, rice husk and returned dairy manure compost as supplementary material were investigated. The mass per unit area and the bulk density up to a deposition height of 3 m were estimated from initial bulk density and the regression equation of the settlement rate of the load test using a small vessel. The initial bulk densities of dairy manure mixtures were 60 % to 70 % of those of swine manure mixtures in saw dust and rice husk mixtures, and 40 % in returned dairy compost mixtures. The amount of subsidence tended to be larger for materials with higher moisture content, however the amount of subsidence at the maximum load was generally larger in the order of returned compost mixture, rice husk mixture, and rice husk mixture. The estimated bulk density of the dairy cow manure material obtained by this study was smaller than that of the swine manure material, and the previous value using the same type of material was about 70 % to 80% for both sawdust mixture and rice husk mixture, and the returned compost mixture was 50 % to 60%. The reason for this is considered to be the difference in the dry mass ratio between the manure and the supplementary material, and the difference in the experimental operations.

View full abstract

Download PDF (1006K)

Register with J-STAGE for free!