Rashi: This is how one plows. He levels the face of the land, and afterwards seeds.

Radak: "Im" is like Ka'asher (when). The same applies to "v'Im Yihyeh ha'Yovel" (Bamidbar 36:4). When the face of the land will be level, i.e. he crushed the clumps, the furrow is even, so that the seeds will fall evenly.

Malbim: If it is even, then he begins to seed.

Rashi: If he comes to seed black cumin, he seeds it scattered. If he comes to seed cumin, he seeds it via throwing.

Radak (25, 29): Afterwards, Hashem began to seed - He brought His Shechinah on Har Sinai, and all of them became Nevi'im - each according to his intellect. The sharp, spiritual ones are like soil that was crushed very fine, which is proper to seed Ketzach and cumin; they are for taste, not to be eaten themselves. Less refined people are like grain; it does not need such fine soil, but still there are distinctions - wheat is finer than barley and spelt. One who seeds hopes to get many more seeds than he planted - so Hashem hoped that Yisrael will grow wiser, and understand a matter from a matter - "Ten l'Chacham v'Yechkam Od" (Mishlei 9:9). Every crop has its way of seeding.

Rashi: If he comes to seed grain, he seeds wheat in the middle of the plowing, and barley around them, and spelt on the borders of the field. The wheat is in the middle. It is Shoreh ¹ over the barley and spelt (it is in the most important place).

Radak: Shorah is a measure, like "ba'Mishkal uva'Meshurah" (Vayikra 19:35). It is an adjective for something given in a measure. It is feminine, for it describes Chitah. If one puts the wheat in a known place in the field that is good for growing wheat, he seeds it only according to the measure, lest he detract from the land. Also barley he demarcates that barley was seeded there. Also spelt is in a known place, on the border. Every species is in its proper place; the verse mentions these, for they are the primary food of people and animals. Also Ketzach v'Chamon are spices needed for human food.

Malbim: Plowing represents Galus and afflictions that Hashem brings on the nation equally. Seeding, i.e. learning Torah and Nevu'ah, varies according to the recipients' preparation. Those who are prepared for Chachmah, a small hint suffices. For ignoramuses, one must repeat over and again, and explain little by little. Also, Chachamim understand the contents of the Chachmos and their inner truths; the ignoramuses know only the stories and garment in which intellectual Divine matters are clothed.