To remove the obstacles you encounter on the purchased land in the Sands, you will need special tools.

Different types of bushes: Work tool

You can produce work tools in the Cargo Port.

Different types of cactuses: Traveler's map

You can obtain a traveler's map for completing a special order in the Trader's Tent.

Columns, rocks: Traveler's maps and pathfinder's tools

You can obtain a traveler's map for completing a special order in the Trader's Tent. 
You can obtain a pathfinder's tool for sending caravans in the Trading Oasis. 

Different types of palms: Work tools and pathfinder's tools

You can produce work tools in the Cargo Port. 
You can obtain a pathfinder's tool for sending caravans in the Trading Oasis.  

Stones, rocks: Traveler's maps, pathfinder's tools, work tools

You can obtain a traveler's map for completing a special order in the Trader's Tent. 
You can obtain a pathfinder's tool for sending caravans in the Trading Oasis. 
 You can produce work tools in the Cargo Port.