Not all prepositions are created equal.
Some prepositions need to be followed by ablative as you say. Examples are cum (e.g. cum Ipso), sine (sine Deo nihil), de (de hoc mundo).
Yet most prepositions need to be followed by accusative, like ante (ante constitutionem mundi), per (per Ipsum), post (post mortem).
A number of prepositions may be followed by both acc. and abl., with different meanings, as in, sub, super. The rule of thumb with these three is that accusative adds movement to the meaning of the preposition:
- in+[abl] → in, on, at;
- in+[acc] → to, into, towards.
In the quote from Deuteronomy, the seed is to be thrown to the ground.
See also: i) L&S entry for in, and ii) this list (and also this one) of prepositions and the cases they are followed by (none of both is exhaustive, and the exact content of a complete list is disputed).
In the lists you can see that some are said to be followed by genitive, like ope, and tenus. These are listed by some as prepositions, but not universally agreed as such. My perception in this issue is they are nouns in the process of mutating from/to prepositions by gaining/losing cases (either created by generalization or falling out of use). Note that ope is said by L&S to be the ablative of ops, which itself is not attested, being another example of a defective paradigm. Other cases of ops are also rare.
