In one of the pie slices of crop circle nr 1 I’m trying to make my own black earth. Each year in the fall I buy some bags of charcoal, infuse them with nitrogen rich liquid (urine, old milk and such) and then spread it out on the same section of dirt after harvesting and turning it over. 

I treat this section like the rest of the circle but with less compost and other additives. I want to see if it really makes any difference. So far, after 4 years, none noticeable.