"We need to produce more food."
Translation:Vi behöver tillverka mer mat.
Is there a reason not to use "fler" here? They just used it the previous example ...
So in this example you can just use "tillverka", but in another example: "Det tar fyra dagar att tillverka den" you need to use "att tillverka". But I thought the need to use "att" depended only only the verb that followed it?
No, it depends on the verb that goes before it. In this case, behöver is one of the modal verbs, and after them we never use att with the infinitives.
Well, you can't be sure about non-modal verbs, there are different cases with them. Sometimes the att is needed, sometimes you can't have it, and sometimes both ways are possible. So it's only the modal verbs you can be sure about, the others you'll have to learn individually how they work. (I hope I'll get around to write a list about which works how eventually, but it may take me some time).
Would DL have accepted: vi behöver framställa mer mat? I thought of that first but changed it when I checked the suggestions provided. To me -tillverka- is more like producing eg cars, whereas -framställa- seems more appropriate for agriculture, making something from (almost) nothing.
Is there a reason why "behöver att tillverka" is wrong? I thought the att was optional, but not wrong necessarily
Yes, we don't use att with behöver. att between two verbs is sometimes optional, sometimes required, and in some cases not allowed, so all three cases exist and it varies depending on the first verb. The main tendency is that modal verbs and verbs that are similar to modal verbs don't take att. Here's a link to a little more detailed explanation: https://www.duolingo.com/comment/7075383