You are good texture data ?. Seems to have a silt loam soil, so the bulk density may be between 1.10 and 1.20, but in any case, would not it be better evalues the bulk density, taking samples, for example by the method of cylinder ?

Please follow the pdf attachment for the method of estimation of bulk density.

If you know soil organic matter (OM, %) status, you can try this from Saxton and Rawls 2006 SSSAJ 70:1569-1578. You can try this in excel or write a VBA code to calculate BD.

Note: clay and sand are fractional, OM in %

Step 1: 

x1 = 0.299 - 0.251 * Sand + 0.195 * Clay + 0.011 * OM + 0.006 * Sand * OM - 0.027 * Clay * OM + 0.452 * Sand * Clay

x2 = -0.015 + 0.636 * x1 + 1.283 * x1 ^ 2

VolumetricWCAt33Jkg or Field Capacity (FC) = x2

Step 2:

y1 = 0.078 + 0.278 * Sand + 0.034 * Clay + 0.022 * OM - 0.018 * Sand * OM - 0.027 * Clay * OM - 0.584 * Sand * Clay

y2 = -0.107 + 1.636 * y1

Porosity = 0.043 + FC (from step 1) + y2 - 0.097 * Sand

Bulkdensity = (1 - Porosity) * 2.65

Try this and let me know if it works or how good is it compared to measured values.

Thanks!

Thank you Debasish. I will try but I have two questions:

1) What about silt %?

2) Sorry for my lack of language, what do you mean by "fractal" number? 

Hi Matteo, you do not need to use silt. When you use sand and clay, it automatically accounts for silt, as three of them makes a 100%.

Fraction means using 0.19 instead of 19% sand (as in your case).

I hope it helps!

I suggest you to read related paper at http://www.sciencedirect.com/science/article/pii/S1878029615003242