No idea about Turkey but in Romania it ranges from around 800 Euro per hectare to take your pick!
Generally in a rural area, if it was a question of a hectare or 2 here and there (i.e. not together), the price is around 800 Euro/per m2 depending on the region.
If it's a question of a number of hectares together (say up to 30-40) then you're looking at around 1200 - 1800 Euros or thereabouts.
Above 40 hectares, and for land which has little hope of being rezoned and is likely to remain purely agricultural, the prices rise steeply starting around about 2200 Euro/hectare up to say 3000 Euro/hectare.
As regards agricultural land within, say 10 - 15 km of a big city then you could be looking at anything from 12 Euros/m2 to the skys the limit! The reasoning being that its going to be rezoned sometime as said city expands or the satellite towns around that city rezone to take advantage of their proximity to the city.
Basically all agricultural land anywheres near a city, town or village can be rezoned but the taxes which must be paid to do so can be up to 100% of what you paid per square metre (in the case of Grade 1 land). This may or may not make it worth your while doing. Also it is NOT enough, as every chancer of a romanian real estate agent will tell you it is, to rezone at a local level, for example the Town Hall. This is not a valid rezoning all though it goes on a lot. The only way to rezone properly is with the written approval of Bucharest. The land has to be expunged from whats called the 'Circuit Agricol' or agricultural land register
By the way this is all for Grade 1 land. There are, as I remember off the top of my head, 3 gradings depending on the quality of the land.
Incidentally when reading the small ads regarding land the important word where multiple hectares are concerned is 'comasat' i.e. the parcel is one, not dotted around all over the place.