If your barn is full which causes you cannot perform most of the in-game actions, you need to clear up some spaces. This can save you the time and trouble of growing or producing necessary goods. For example, with 200 market boxes, you can select from 200 random goods every 6 hours when the market refreshes, and this way you can instantly supplement any goods you may be lacking.
With enough market boxes, the City Market can function like a second barn - in that you can buy more of almost any good you need at the moment. Market boxes reach a fixed cost of 30 Tcash each, but an unlimited number of boxes can be purchased. Purchasing market boxes or hiring the dealer are the best ways to spend Tcash. If you don't have as many fields, or haven't unlocked certain crops you can find a balance by keeping fields with about 70-80% slow growing crops and 20-30% fast growing crops.
You can produce goods and leave them on shelves until you are ready to use them.
The barn's appearance will change as you upgrade capacity. Tapping the upgrade button shows how many hammers, nails, and paint you will need to increase your Barn Capacity to the next level. Tap a goods picture to view their values and sell your chosen quantity using the (-) and (+) buttons, but it is recommended to use transport to sell your goods. Using the tabs in your barn your goods are categorized by all goods (ALL), crops, farm/ factory goods, island goods, construction materials and ingots from the foundry. coins, T-cash, gems), coupons, zoo cards and certain event items don't need a storage place. Mining tools, ores and clay are stored in the warehouse at the mine. The barn is where most goods are stored such as factory products and construction materials.