3.2. Soil bulk density and soil water content
Organic materials have low bulk density and higher porosity, so the mixing of organic materials with denser mineral fractions of soils causes a decrease in bulk density (Martin and Stephens, 2001 and Bronick and Lal, 2005). Decrease in bulk density and increase in SOM with organic fertilizer applications have been also reported in different soils at different application rates (Zebarth et al., 1999). However, most of former investigators did not consider the total N, P, K from the organic manure and inorganic fertilizer uniform among treatments. We here conducted the experiment on the base of the same total N, P, K application rate, thus proved the functioning of organic manure in decreasing soil bulk density more clearly.