I appreciate the good question of Mr.Binay and interesting replies /comments by colleagues .Bulk density one way reflects the soil structure,the type and arrangement of soil aggregates along with distribution of pore and cracks between them. B.D. is  some times used as a measure of soil structure.Dr.George Ray has very well described the measurement of it. Micro porosity will be more in fine textured soils while macro porosity will be more in coarse textured soils.Bulk density is affected by organic matter status of soil and soil management practices as as highlighted by Dr.Arthur and other colleagues.Bulk density values will be high for sandy or sandy loam soils with poor aggregation  while lower values can be found in clay and clay loam with good aggregation.While  soils with lower bulk densities  reflecting good structure and less compaction help in good root growth of plants ,the soils with higher bulk densities and  greater compaction reduce or restrict root growth.With in a textural class, the bulk density can vary considerably,because of variation in organic matter status  and management practices which improve porosity (less compaction).Mr. Binay,the B.D of 1.0 g/cc  may not be expected for sandy loam but it can vary from around 1.4-1.8 g/cc.Dr.Singh and Dr.Panday provided good references which may help you.

Bulk density of soil is an indicator of soil compaction. It is calculated as the dry weight of soil divided by its volume. High bulk density indicates low soil porosity and soil compaction. Clayey soils have greater bulk density than the sandy soils. Please check the pdf attachments for details.

Hello Binay Sa. May I ask you of which soil material do you measure the bulk density? Did you measure the density of the bulk soil? Or are you talking about the density of the fine earth (

 Indeed the soil bulk density indicates the degree of soil compaction, but not only that, it is also an indicator of the infiltration capacity and pororsidad and degree of soil aeration. In addition also it influenced by the structure and organic matter. As regards only the texture, the high values correspond to sandy soils and low to clayey soils.

Hi Binay, If I understand correctly, you mean you have soil which has a texture of sandy loam (one textural class) with a range in bulk density (BD) as wide as 1.0-1.8? If this is correct, there is no need to relate BD to soil texture since you only have one textural class at your site. I suggest you consider determining the organic matter content for your site (loss-on-ignition method will be the quickest way). I suggest this because BD will, in most cases, decrease in increasing organic matter content. Secondly, are the management systems (tillage, fertilisation and cropping system) of your site identical? These also have a significant impact on the density

Exactly correct Emmanuel! I wish to add further that bulk density represents the natural density of soil - natural means as they do exist in nature. In nature the volume of a soil is not determined by the particles alone in it but the voids and capillaries it contain. A cube of (of known volume)  undisturbed soil (better taken using the "Kubaena box') is to be taken from the field and its mass must be calculated after drying. This mass divided by volume will give us the natural density of the soil.

Now to calculate the particle density we need to break the cube of soil mass into powder and the actual volume (volume minus the voids and capillaries) of the soil particle may be calculated by water displacement method.

Bulk density and particle density is the clue to porosity and capillarity of the soil which may be calculated indirectly from formulas once both these densities are known

Particle density has no relationship to texture; but it has relationship to the mineral content of soils; Ca/K/Al  minerals are less denser than Fe minerals. Particle density  of mineral soils in general is usually 1.8 because most of the soils are made of a complex of several minerals and the  particle size won't affect its density. (Of course the particle density of organic soils are much lower). Since organic content of mineral soils usually do not exceed 1% it won't considerably affect the particle density  of a soil. Particle density of soils can be up to 2 (in extreme cases). In practice, if a soil is said to have a particle density of 1.8 means it has least air space inside and is a highly compact soil. Particle density cannot say anything on the  texture of a soil!

I appreciate the good question of Mr.Binay and interesting replies /comments by colleagues .Bulk density one way reflects the soil structure,the type and arrangement of soil aggregates along with distribution of pore and cracks between them. B.D. is  some times used as a measure of soil structure.Dr.George Ray has very well described the measurement of it. Micro porosity will be more in fine textured soils while macro porosity will be more in coarse textured soils.Bulk density is affected by organic matter status of soil and soil management practices as as highlighted by Dr.Arthur and other colleagues.Bulk density values will be high for sandy or sandy loam soils with poor aggregation  while lower values can be found in clay and clay loam with good aggregation.While  soils with lower bulk densities  reflecting good structure and less compaction help in good root growth of plants ,the soils with higher bulk densities and  greater compaction reduce or restrict root growth.With in a textural class, the bulk density can vary considerably,because of variation in organic matter status  and management practices which improve porosity (less compaction).Mr. Binay,the B.D of 1.0 g/cc  may not be expected for sandy loam but it can vary from around 1.4-1.8 g/cc.Dr.Singh and Dr.Panday provided good references which may help you.

Dear Dr Binay Sa

Bulk density is more an expression of the state of aggregation in given soil , so it's more related to Soil structure ( as it's a dynamic properties) than soil texture which is a static properties in a given Field. 

So i suggest that you interpret your result in fonction of the factor that affect the state of aggregation ( Soil water content at the time of measurement,  The ESP of soil , the Organic matter content, the type of clay).

Kind regards Louadj yacine

My colleagues have provided the most relevant and useful articles and comments. I want to add one simple observation, which may be of any use. Sampling is very very important for estimation of bulk density in field. The point and time of sampling may significantly modify BD. Sampling closer to the root zone at young stage (when roots do not grow extensively) and later stage (roots grow in volume and length) may markedly affect the estimation. Most of the times we tend to ignore to exclude the root volume. Presence of a burrow/ insect hole/ earthworm hole may reduce the estimated bulk density within same soil texture in a short crop growing season. Similarly soil moisture content (saturation or field capacity), especially with presence of shrink-swell clay mineral may have significant effect on field bulk density estimation. Accordingly, it's more pertinent to report soil moisture content during BD estimation.

I appreciate good and practical points mentioned/raised by Drs. Yacine and Borah .Even though we advocate field /undisturbed cores measurement of bulk density,there are several problems and possible solutions which one has to carefully note.Are there any bulletin/practical manuals on field measurement of bulk density?ESP of soil,soil moisture,root growth dynamics,soil animal activity etc.(as mentioned by colleagues above) influence soil B.D estimation.To minimize the errors,when and how to estimate soil B.D?

Dear Dr. Emmanuel Arthur,

Thank you for your answer. My study site is undisturbed forest of central Himalayas in Uttarakhand of India. I have already calculated soil organic carbon (Walkley and Black) and organic matter content (Loss on Ignition).  Now, I will relate these data with bulk density of soil.

Dear All,

Thank you for making the discussion interesting and insightful. I thank you all for providing detailed insights on soil bulk density and its other physical parameters. I will incorporate your suggestions in my study and I hope to get such feedback in future too.

The answer, my friend, is blowin' in the article (Bob Dylan):

STOLF, R.; THURLER, A. M. ; BACCHI, O. O. S. ; REICHARDT, K. . Method to estimate soil macroporosity and microporosity based on sand content and bulk density. Revista Brasileira de Ciência do Solo (Online)📷, v. 35, p. 447-459, 2011. Article Method to estimate soil macroporosity and microporosity base...

Useful answers to the researchers and thank you dr. Arvind Singh and Rubismar Stolf for all the useful attachments. thank you Binay Sa. and I following.

Would you please mention the method you followed to determine BD? Best result is however obtained when one uses core of 100 CC. In sandy loam textured soils a BD of 1,8 is unusual until the soils is compacted by any anthropogenic activity. Some such example was obtained in IGP soils. The reference is given below.

Chandran, P., Tiwary, P., Mandal, C., Prasad, J., Ray, S.K., Sarkar, D., Pal, D. K. et al. 2014. Development of soil and terrain digital database for major food-growing regions of India for resource planning. Current Science, 107: 1420-1430.