I have tested a brownfield soil and another soil from woodland site for their pH,zn concentration and humus?

Question

brownfield: zn= 241.47mg/kg , pH=6.78.humus content= 4.3% i have to put a reason why is the pH high? because i expect it must be low bcz of high ZN AND LOW HUMUS CONTEN

for the woodland soil: Zn= 61.82mg/kg , pH= 3.92 humus content= 12.15,,,,how can i explaine the Ph value of this soil? i mean is it reasonable?

Answer 1

I don't know about the zinc but 6.78pH is not so high especially if the soil has a little CaCO3 and/or MgCO3 in it.

As for the woodland soil's pH:

3,92 would be considered fairly acidic. Forest soils are usually

acidic anyway especially if there are no rocks with calcium in it.

From 3,92 I would guess that this forest consists of coniferous trees, or the area has much precipitation.

As for the Humus: on the acidic ground the organic stuff doesn't break down fast so there can be excessive humus build up, this is especially true in the arctic where these creatures called lychenes can form several feet high layers of organic stuff when they are dead.

Anyway I think your results could be reasonable although more info is needed to judge that. (like what geographical location, what kinda vegetation, climate and stuff like that)

Sorry for the bad english, hope I helped.

Answer 2

I can't really explain your results with the information that you give us here,  Do you know the liming history of the brownfield soil?  The pH of the soil is almost ideal for cropping which would suggest that it has limestone regularly applied.

For the woodland site you would expect the humus content to be high with accumulated leaves and other decaying organic matter.  The pH is very low even though you would it to acidic in a woodland which limestone has never been applied to correct it.  I would suspect your sample collecting might be the cause of some of your results but, of course, I know nothing about how you took your samples.