Before you put a lot of effort into it, why don't you have a soil test done on the soil there? It may be massively unbalanced to the point you will be wasting your time without making some corrections.

Contact your local Cooperative Extension Office (see below) and ask them who does soil tests local to you. Mostly, the basics should cost you about $10 per test.

Personally, I would have two tests done. Wash off a shovel blade that doesn't have rust on it (rust will throw off the results), and shove it straight down (or close) into the soil and lever up the shovelful of soil, toss it aside.

Then carefully back up an inch or a little more, and push the blade down again so you're getting a slice of soil. Carefully lay this slice on an open newspaper, keeping it together as much as possible (like a cake slice).

Sample 1: You're going to want about one-plus cup of soil, so use a clean, non-rusty trowel to 'sub-divide' the slice. You want from the very top of the surface (chick poop and all) down about 6" and wide enough to give you a cup or a little more. Collect this and put it into a flattish clean container.

Sample 2: You want this one to be mainly all soil, without the chicken poop 'icing'. If you can get it from the slice of soil that you got the first sample from, fine; otherwise, take a new slice from the same hole. Try to determine where the line is between the actual soil and the layer of poop, then discard all the chicken poop, and measure 6" down and collect your cup+ or so of soil. Put it in a separate clean container. Mark them: soil with chicken poop, soil under chicken poop.

Break up each sample as much as you can. Pick out all plant material, roots, rocks, pebbles, sticks, and debris. Try not to handle it with your bare hands.

Place in a safe place in the sun (no wind) and stir them occasionally until they are dry. Bag each sample in a LABELED ziplock plastic bag. Deliver to the soil testing place. If you garden organically, be sure to write ORGANIC on your paperwork and on the bags, as that will alter the recommendations they make. It would probably be a good idea to tell them what you are trying to do, because I have the feeling that your results are going to WAAAAY off the usual.

I wouldn't do anything until you get the results back. If you have further questions on the recommendations, call them and ask. They're here to help, and your tax dollars are paying their wages.

Sue

2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains� too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer your soil will smell.

5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.

to see what else you can about this soil. As feijoas has discovered balance is the key. An over abundance of nutrients is not necessesarily good.