Poor working

One thing I forgot to mention is pickup trucks. Some folks just think people are nuts for buying tractors when you got a pickup truck around. 6ft discs not too agreesive or a 8ft spring harrow would work. I'd go for the spring harrow. Folks even convert rear axles to tow powered brush hogs for their trucks too.

That hand me down ATV disc, I'd sell it and get a drag harrow. If keeping it, I'd cut the agressiveness down on it. ATV's aren't going to get a 6+ inch deep till. A 1 inch seed bed is all you need in many cases. some cases, just scuffing it up enough to see some dirt will work with small seeds too.
 
I forgot to mention, discs work better on mosit soil. Dry soil they can wander around like you mentioned.

If you breaking sod, best to get a tractor in there to flip it with a plow.

I think the emission control equipment only applies to 50hp and higher tractors. Maybe it was 30hp. Most little guys dont have them.
 
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