What did they over fertilize it with? Some fertilizers move (wash) out of the soil rather quickly. Others stick around. I agree with the soil test suggestion. I get one every year. They are very informative, and save you money in the long run because you will not have to apply a bunch of nutrients that are already in your soil. A balanced soil is easy to obtain with the help of a soil test. Its a guessing game without a soil test.
Another way to analyze is to look at the weeds that are thriving. What weeds are growing in the plot, and how do they look? If weeds aren't growing, you may have an excess buildup of salts that is creating a toxic situation. If weeds are growing lush and healthy, depending on which weeds, you might be allright. If you can't get a soil test, at least get a book out of the library that tells you how to read your soil through the weeds that are thriving ("Weeds and What They Tell Us," "Weeds, Control Without Poisons")
I highly recommend soil tests done by Cook's Consulting. It costs just $27, and is very thorough. They give organic recomendations if you request such. Peg Cook helped me take my soil from poor and unbalanced with a toxic excess of heavy metals to healthy, balanced, and very fertile in just one year. The difference in my crops is just amazing. I would have applied the wrong stuff and created a further imbalance without the soil test. You can find a link to her website at LewisFirst.com.
