Dear Mohammed

You can find many paper focusing on the topic of GIS-based agriculture suitability analysis, just search the keyword from Google scholar's database. However, it seems to me that Rank assignment as related to soil characteristics is a specific methodology from a paper that you have read. So I think it's better for you to understand this method first or find more paper, book or other publication having specific details like index setting or analysis process.

Maybe this one is helpful.

Best regards

Kai LIU

Conference Paper Research in Crop Land Suitability Analysis Based on GIS

Check thes links;

https://www.sciencedirect.com/science/article/pii/S0309170801000343

https://www.researchgate.net/profile/Shohreh_Liaghat/publication/46179269_A_Review_The_Role_of_Remote_Sensing_in_Precision_Agriculture/links/0f31752f92d2ee1369000000.pdf

Best wishes

Dear Kai LIU,

Actually, you dont need to write anything if you dont have a specifice answer. I ask exactly about the (Rank assignment for Soil characteristics ) because I cant find a proper one.

So, if you can help it is ok, in other case save your advice to yours.

Thank you.