I usually clean 'em up first with a wire brush, then I use "plumbers cloth" to sand the post and terminal until they're "bright". Install, then I cover everything with a thin layer of grease. That keeps air away from the metal, retarding corrosion.
In a tractor application grease might get you by but over 35 years of working on automobiles I have fixed more connection problems by removing the grease on battery posts/terminals than anything. It's probably the underhood temps melting the grease down between the post & terminal, then it always seems to form a hard crusty coating that makes for poor electrical contact. Besides the corrosion from disimilar metals the thing that causes the corrosion is usually the hydrogen sulfide gas leaking past the post to case seals - some batteries have better sealing than others. I always use one of those impregnated felt washers on the post - it seems to neutralize the gas as it escapes around the post. I also coat all with the spray-on sealer, getting the underside soaked good as well as on top. These sprays don't melt and get between the post & terminal to cause later problems.
Do not do this! The baking soda neutralizes battery acid. If any of this solution gets into the cells, kiss your battery good-bye. I saw a rookie ruin a $3500, 36 volt forklift battery by doing just this.