Non-clogging coulter assembly

A coulter assembly comprising:

• a coulter blade presenting a diameter and a lower margin;
• structure supporting said coulter blade, including a parallel linkage arm assembly comprising upper and lower pivotal linkage arms, and an elongated, obliquely oriented piston and cylinder assembly secured to said supporting structure and operable to maintain the coulter blade at a substantially constant depth as the coulter assembly traverses the earth;
• a knife located adjacent and rearwardly of said coulter blade and oriented to present a horizontal nip at a lower portion of the knife, with a nip distance between said lower knife portion and the adjacent edge of said coulter blade;
• and
• an adjustment assembly supporting said knife and including structure for selectively adjusting the height of said knife relative to said lower margin of said coulter blade between an upper and a lower position, said lower position being at a level where said nip is a distance above said coulter blade lower margin equal to about 5% of said coulter blade diameter, said upper position being at a level where said nip is a distance above said coulter blade lower margin equal to about 15% of said coulter diameter.