Maria,

(Preface: I'm not a heavy DSSAT user, so I'd like to hear if anyone
has a different opinion.)

If you have not already done so, I would suggest doing a couple of
test model runs where you switch back-and-forth using each of the bulk
densities you have calculated, then seeing if the switch makes a large
enough difference in the model output for it to matter in the rest of
your work.

Hope this helps!

Jason Patton


On Thu, Apr 19, 2012 at 9:38 AM, maria soldevilla
<[log in to unmask]> wrote:
> Thank you very much for the quick responses.
>
> In fact, I took the cilinder samples and measured the dry weight, but I
> also measured the weight of the coarse fraction so I can subtract it from
> the total and and get the density (without stones) dividing by the volume
> of the cylinder, as it is common to give the density on that way. My
> question was which of the two densities should I introduce in the soil
> file, but I guess it is the total one (including stones).
>
> Thank you again
> Maria
>
> 2012/4/19 Jorge Batlle <[log in to unmask]>
>
>> Soil bulk density is measured in undisturbed soil samples (ussually token
>> by
>> insertion of a cilinder of knwon volume, and dividing the dry weight of
>> this
>> soil content by the volume of the cylinder). This measurement can be
>> related to
>> total volume porosity if the real density of soil particles is measured
>> also by
>> picnometer method.
>> If you separed coarse fragments >2 mm and fine fraction < 2 mmm, it means
>> that
>> you already disturbed your sample.
>> I hope this help.
>> Jorge Batlle
>>
>> > The bulk density of a soil, is the ratio between the mass and volume of a
>> fraction of soil, the most important is that the volume fraction have
>> included
>> soil air. This is very important because in the porous part is where there
>> is
>> water movement and more movement of the roots becoming root penetration,
>> among
>> other things, like the movement of nutrients or nutrient uptake by the
>> roots.
>> >
>> > -----Mensaje original-----
>> > De: DSSAT - Crop Models and Applications [mailto:[log in to unmask]]
>> En
>> nombre de fyy0201
>> > Enviado el: Jueves, 19 de Abril de 2012 08:15 a.m.
>> > Para: [log in to unmask]
>> > Asunto: 回复: Bulk density
>> >
>> > Dear colleage,
>> > I am not familiar with the content mentioned by you.So I am sorry and
>> can not
>> help you.
>> > Best regards,
>> > Lily
>> > 2012-04-19
>> >
>> >
>> >
>> > fyy0201
>> >
>> >
>> >
>> > 发件人：maria soldevilla
>> > 发送时间：2012-04-19 21:10
>> > 主题：Bulk density
>> > 收件人："DSSAT"<[log in to unmask]>
>> > æ �送：
>> >
>> > Dear colleages.
>> >
>> > I have a question and may be somebody can help me. The Bulk density
>> coefficient ( SBDM ) in the soil file, is the soil density including coarse
>> elements or without them? I'm not sure which density I should write.
>> >
>> > Thank you very much
>> > Best regards
>> > Maria
>> >
>> >
>>