I saw this last night, and I hesitated to comment on it, because I believe there are some situations where local input is best - and I believe this is one of those situations.  However, I decided that I will comment.....

I have concerns about farming slopes with organic, especially with 20% slopes.  Contour farming is best - it will help to minimize (not eliminate) erosion.  Farming up-and-down-the-slope is a bad idea, especially if you are doing lots of tillage and cultivating, which I expect in an organic system.  

You mention 20% slope. How much is 20%?   What is the average - or typical - slope of this tract?

A couple of thoughts:

a) farm on the contour, as mentioned about.  Also, consider strip cropping.  Maybe lay out 60-foot wide strips, or 90-foot wide strips.  Plant alternating strips into spring crops - corn, milo, soybeans, etc.  Plant the opposite crops into a fall seeded crop - wheat, barley, even rye cover crop.   Consider broadcasting an adapted clover into the wheat/barley/ rye, so that is growing over the summer time.  In the following year, you plant the corn/milo/soybeans into the strips that had small grains in them.

b) think about laying out the strips based on the width of your equipment.  If you equipment is 15 feet wide, make your strips multiples of 15-feet; If your equipment is 20-feet wide, make your strips multiples of 20-feet wide.  If your equipment varies in width, think about how you reduce this variability. 

c) depending on how much of this tract is 20% slope, you may want to plant the really steep parts into permanent grass - whether to make hay, or just not row crop farm it.  Also, when laying out your strips, you may have small swaths between each strip where it does not get planted, that stays in permanent grass.  That is okay, if it helps you keep erosion under control.   Maybe even think about how you can use these areas for pollinator crops - (something I suspect would be encouraged in an organic system ?)

d) when you are talking "organic", I think back to the 1940's/1950's - before the advent of no-till.  Think about some of the practices that your grandfather would have farmed with - such as strip cropping, rotating spring and fall crops, etc - and that might give you a good idea of what you need to do to use organic on slopes.

e) lastly, don't be against contacting your local NRCS office and asking for advice on what would be needed to keep erosion under control in your locale. Know up front what they can and cannot do for you, before you have to "sign on the dotted line".  I am sure you can have a discussion with them, and not have a commitment.  Whether they can run RUSLE for you, and have no commitment - that I cannot answer.  I think there is value in talking with them, as they would know your locale, and what in general will work for erosion control, and what will not.

edit: one final thought - do you have  a local/state organic crop producers association? If so, they might be helpful in giving advice on farming slopes organically.  (?).