The final bulk densities for G, GBIO and GDEG were found to be 267 kg/m3, 326 kg/m3 and 259 kg/m3, respectively, as shown in Table 2.Typical dry bulk densities are in the range 100–400 kg/m3, whereas wet bulk densities are typically 500–900 kg/m3 (Agnew and Leonard, 2003).Bulk density is dependent on the location within a pile, and, samples from the bottom of the pile had higher bulk densities, and higher values of bulk density imply an increase in mass and a decrease of porosity and air volume.The ability of compost to hold and retain water is also important to the user. Water holding capacity is obviously related to the structure of the compost matrix.The compost matrix depends on certain factors that influence the amount of air that can be held in the compost, which, in turn, have a direct bearing on the ability to sustain aerobic decomposition.These factors are the sizes and distribution of both particles and pores. The water holding capacity of G, GDEG and GBIO composts were over 90% higher than that for soil.