This is quite an unusual type of missions, as theoretically, you won't need any new special equipment to complete them - you already have a tractor and a trailer. The problem is that you need to have a lot of supplies, which you will deliver to somebody (sometimes it's even more than 50t). The task consists in loading the crop onto a trailer, delivering it to a given shop and then unloading (you don't have to do it in one trip - you can drive there as many times as you want). The mission itself is very easy, as long as you have the right equipment - and this is precisely the reason for which you should complete this type of missions at more advanced stage of the game, when you're farm is well developed. Firstly, you will then have a better tractor with a bigger trailer, which means that you won't need to make a lot of trips and the probability of earning a bonus for time will increase. Secondly, you need some solid supplies, which you won't probably have at the beginning of the game.
The reward for these missions varies depending on the amount of goods that you have to deliver. It's not very high, but the bonus is. The bonus is precisely why you should take interest in this type of missions - the additional reward can be even 40 - 50 times (!) bigger than the basic reward. Moreover, remember that you also earn money for the goods you deliver. When you have a lot of supplies, completing missions becomes more profitable, especially when you do it fast. You will then receive money for the transaction and a high bonus.
Required equipment: a tractor with a trailer (preferably one of the stronger versions with a large tipper), appropriate supply in the silo.
Profitability: huge, as long as you earn the bonus.
Reward: about 10 000$ + optional bonus (even up to 400 000$ - 500 000$),
These missions are a good way to get rid of crop lying in your silos. It is illogical (and impossible) to buy new machines only to complete this kind of tasks - the equipment and supplies come with time.