Hi Alice, You should not consider the stones or the fragments > 2mm in diameter in your BD calculation. This is because we consider only particles < 2mm in diameter as the soil separates or fractions. Therefore, you should not consider those particles. However if there are stones or other foreign material, you need to determine the volume and mass of those materials such as stone and deduct from the original volume and mass of the soil core. Then only you will get the exact BD. Measurement of BD is one of the problematic and trickiest business in soil physical analysis.

Bulk density is the ration of the total soil solid to the total porespace of the soil expressed in percentage means it varies from soil to soil clay soils are having lower bulk density than coarse texture soils. For detemination of bulk density there is no need of mixing of stones otherewise it affect the bulk density of soil

Hi Alice, You should not consider the stones or the fragments > 2mm in diameter in your BD calculation. This is because we consider only particles < 2mm in diameter as the soil separates or fractions. Therefore, you should not consider those particles. However if there are stones or other foreign material, you need to determine the volume and mass of those materials such as stone and deduct from the original volume and mass of the soil core. Then only you will get the exact BD. Measurement of BD is one of the problematic and trickiest business in soil physical analysis.

Thank you very much

Dear Alice,

You should consider the stone content if it is large enogh to affect the soil properties of your interest, e.g., soil water content. It will raise your soil density, of course, but care should be taken in the measurement of the total volume of the sample, which is not so easy in stony soils (>10% in volume).

Hello Alice, In addition to what was said, I suggest reading the article "10.1071/ SR04054", in which the authors measure the density excluding regions of higher or lower density in relation to the average soil bulk density obtained through gamma ray computed tomography.

Dear Alice.,

I tested the effect of stone percentage on bulk density using DSSAT model, and the result is that this parameter does not effect on bulk density.

Dear Alice,

The question has been adequately dealt with in the answers given above

Which method u can use for bulk density of soil ?

Since stone is also intrisic property of soil, including it as part of bulk density calculation is OK. Otherwise, you will be presenting a result that is far from natural reality.

According to me soil bulk density should not be calculated by adding stones in it as both do work when used together but still have different properties of weight texture etc. So adding stone to it can only be helpful only in a few soil types.

Thanks for all the input......I'm doing a comparison across my field site and with depth, so I've assessed BD (known volume of sample oven dried at 105degC) with and without stone content, so although the resulta are different, comparatively there is no significant difference......which is what I wanted, so I'm happy :)

my opinion would be: it all depends on the use they're going to have the results, why?

because we all know that although the rock is on the ground, not in the deficion of this, however, some require knowledge esttudios total apparent density to meet such infiltration capacity of estructuraccion, degree of weathering, etc., then in this case the method to know the density of that soil would be by the method of the trunk and there if you take into account the rock material, otherwise the method would be the method of the cylinder and there only takes into account grain size

According to ISO 11272 "Soil Quality - Determination of dry bulk density" stones have to be included in the measurement. 1.6 g/cm3 is not extremely high.

@ Alice , pls. try to understand bulk density and particle density, bulk density is in range of 1.3 and soil particle dens. is around 2.6,

now , see bulk means you have to collect an undisturbed soil sample from your soil bed using core cutter, now u have volume of core cutter equal to volume of soil sample, weigh it , and divide (dry weight) by measured volume,

what are the contain in undisturbed sample may be stone, silt, sand , soil... that characterize later on as a type of soil, you are not allowed to separate stones or disturbed soil sample collected by core cotter, so automatically stone mass which is in soil sample involved (else you have to think for particle density)

that's what bulk density is , kkkk

The question whether or not to include stones for the purpoe of bulk density measurement is borne out of field conditions prevailing for a given situation, I suppose. The question could be posed this way. Why I should not include for bulk density measurement the stones which are naturally existing in the soil which I work with. What relevance is there in a laboratory measurement of soil bulk density which excludes the soil particles beyond 2mm diameter as it sounds for me unrealistic.

You need to consider all fragments in your bulk density measurement if you are doing any analyses that will give you a value for an element as a fraction of the total soil, basically any mass balance calculation. Measurements such as organic carbon, base cations, pretty much any lab analysis will require this. C/N ratio...maybe not. You can use your ocular estimate of voume, convert to mass, and estimate the contribution of large frags to Db, but you need to have it.

The best technique is to use compliant cavity methods. Excavate a hole large enough to give you a reasonable contribution of fragments(try not to favor the inclusion of anything if possible), place a large sheet or plastic or a garbage bag into the hole, fill it with beads, styrofoam, beans, whatever you have, then remove them by a bucket or other scoop with a know volume. Dry and weigh the removed portion of soil.

Aaron's suggested technique sounds sensible, scientific and practical to determine the soil bulk demnsity. Thank you Aaron.

I very much appreciate the contentions of both Aaron and Jose Navar being absolutely realistic and practical. The soil testing for any parameter physical,chemical or biological need to take in to consideration, its purpose for which a given test is intended for. If it is meant for growing a crop in a field from where the soil sample is collected, stones have to be included in measuring the bulk density. If it is for determining soil property perse from pedological standpoint, standard procedure in which soil particles greater than 2mm size has to be adopted. In essence, it is the end user's requirement and objective which has to be considered in testing.

Since the stone content is part of the intrinsic properties of the soil, it should be included in the calculations. Otherwise, you will be presenting information that is not correct. Including stone content will help with regards to appropritate soil management.

bulk density shows the compactness of soil it veries from soil to soil so please do not include the stone while calculation of bulk density. you can calculate the B.D. of soil by using core sampler or R.D. Bottle

The topic whether or not to include stones for the calculation of bulk density of soils has opened up a moot question. For whom and what purpose the parameter 'Bulk Density' is measured? Failure to fix up the objective for which a given 'Test' is perfomed clouds the direction and procedure is adopted for a given parameter. It is not fair to science as such, to ignore the objectivity of a test. 'Soil test for Bulk Density' when evolved through calibration and standardization by those involved have clearly stated the objective of the test as well as its limitations thereof. It is not to be considered in any case any 'Test' is absolutely fool proof and universally applicable independent ot times. Certain assumptions and limitations are made when a test is standardized. Therefore, it is prudent to set the objective specific to actual requirememnts of a given test and accordingly use them providing due justification for deviation(s) made. Dynamics is the law of nature and we all should welcome it being a part of nature.

Bulk density is gotten from undisturbed sample and stones are considered fragments > 2mm in diameter. It is not possible to sample soil < 2 mm fraction without disturbing the sample. Therefore soil samples collected with core samplers for BD determination contains fraction >2mm in diameter (stone).

No, of course. If the amount of stones is high this parameter (soil bulk density) is impossible to determine, forget it!.

If you can perform the bulk density as usual with limited stone content, but if the quantity of gravel is important, please correct the fine earth from the total soil volume substracting the volume of gravels and stones.

Replicates and representativity of the values of soil bulkdensity is another different question....

Precisely speaking, it is unscientific to deviate from the standard and globally accepted and recognized test and rely on further assumptions and approximations in analytical chemistry or physics. It is a different matter when the original test prescribed is intended for modification and improvement if not for replacement based on fundamental research on physical and/or chemical analysis of soils or whatever.

I agree with the comments of Dennis Edem that bulk density sampling involve collection of undisburbed samples which naturally will contain fragments < 2 mm in diameter. To avoid giving misleading evaluation of soil under studies, I personally do not always remove stone contents from my calculations. Whatever the results will present the true nature of the soil which would guide in applying appropriate management practice(s).