[naturalp]

Hi - I have a small farm.. or smallholding with horses, goats, pig, chickens, Geese and have had a recent soil test because we have lots of buttercups which are taking over despite the land being harrowed regularly, (it's not compacted),  and reseeded (undersown) ever few years.

We live in France, which is the problem as they do things differently here.. and we've been told to start spreading 1/2 - 1 tonne of lime per hectare to correct the Ph and continue for 2 years then have another test in the third year.  That's fine.. but at this time of year all the suppliers have run out of Lime and I can only get lime from the garden centers which is 5 times more expensive... but I can get calcium carbonate (feed quality) in powder or granules for the same price or less than lime. 

question: Would this do the job or would I risk poisoning my animals or wasting my time?

Any ideas? - I've contacted a local processing plant that does lime and calcium carbonate (feed stuff) to ask but I think there is a bit of a language problem!

[Norfolk Newby]

Sounds like fun!

OK

Chalk is calcium carbonate; CaCO3

This is cooked or burnt to remove carbon dioxide and you get quick lime; CaO

Quick lime is very aggressive. It will act like acid on your skin or worse if you breathe in the dust.

So, the manufacturers of quick lime add a little water and this produces slaked lime or 'lime'; CaOH.

Now if you can get chalk, it is almost the same as slaked lime except it has a bit of carbon dioxide attached to it. Guess what happens when you spread slaked lime on your land? It picks up carbon dioxide from the air and becomes chalk!!

This takes a few days but as the lime powder is very fine (small particles) the process is quite fast. The same thing happens when you make lime mortar but there the lime is a solid mass so the carbon dioxide takes longer to react with the lime as it hardens (6 - 12 months?)

Now this is a simplification as the lime is more alkaline that chalk which is only slightly alkaline. However, the effect on land is very local to the point at which the lime particles meet the soil particles. Once the lime picks up the carbon dioxide in the air, the effect is the same as chalk.

I hope my simplified story makes some sense. If I were you I would try the chalk to see what happens. The effects will be less dramatic than with lime but over a few weeks and months, I would expect the difference to be almost nothing.

Just a minor point, have you tried getting lime from the local builders merchants (equivalent to Jewson or Wickes here in the UK). The 50kg sacks that builders use in some mortars is the same as the stuff you want to spread on the land. Don't get plaster as that is a different material - calcium sulphate and is acid rather than alkaline.

NN

[landroverroy]

1 tonne /hectare of lime is a fairly low dosage, so your land cannot be that acidic. Were you not told what the pH (Acidity) was? Calcium carbonate IS lime but to buy it in small bags would cost a fortune compared to the price of agricultural lime.  Are you sure you can't  get agricultural lime at this time of year? Autumn is the time when it is traditionally applied and any agricultural contractor should be able to get it. However, if it's not around,try either basic slag or Gafsa/N African phosphate. Both of these have a high lime content and also high trace element, so will have the effect of GREATLY sweetening your pasture, increasing it's fertility and improving your grass growth to the extent that the buttercups are crowded out.