If land is not personally used and enjoyed (ie, you are not living on it), then it is assessed at its capital value, ie the value that you would get if you sold it. You will have to submit evidence of the value, and it will be assessed against you.
For Supplementary Welfare Allowance the first 5,000 Euro is disregarded. The next 10,000 Euro is assessed at 1 Euro per 1,000, the following 25,000 is assessed at 2 Euro per 1,000 and the balance is assessed at 4 Euro.
This means that if the sale value of the land is say 40,000 Euro, you will lose 60 euro from any claim that you may be entitled to. You'll lose 4 euro for every 1000 that the value is above the 40k.
If you were able to persuade the Community Welfare Officer that this land was part of your residence (which seems unlikely), then it would be land that IS personally used or enjoyed, in which case you would be assessed at the rental value, ie the 2,000 Euro. This would be divided into a weekly sum, and therefore you would lose 40 Euro from your claim.
For more details on how means assessment works for SWA payments see here
http://www.welfare.ie/EN/OperationalGuidelines/Pages/swa_meansass.aspx