Fastest/cheapest way to prep 1/4 acre for spring planting

First of all, hello. This is my first post.

I am looking for AFFORDABLE ways to prep 1/4 acre lawn for spring planting of 3 sisters (dent corn, beans, winter squash), which will be around April here in zone 8a.
Another thing to know about this site is that it tends to be a wet/holds water in the spring. Digging holes in April in the past has shown me that ground water seems to travel along the surface of a subsoil layer about 6-12" down and fills the hole. By May, things have dried sufficiently. It's a silty loam.

Options I'm considering to kill grass and get the plant roots out of water
1) cardboard/hay
    I have access to unlimited free cardboard
    Round bales of hay will have to be delivered.
    Will it be decomposed enough by April?
    Is there a more affordable way?
2) Sod cut and turn to make raised beds or mounds.

Options I'm considering to fertilize
1) fertile holes filled with compostable materials
   Dig a 2-3' hole at every future corn/bean hill
   Start filling with carbon+ raw manure, food scraps, etc until full. Cover and fill the next one
   Will they all be filled AND composted in time?
2) find a source of manure for fertile holes
   I do not have a truck and do not live in a farming area
   Most likely will have to buy bags of manure.
   least affordable option.
3) Is it too late to use a cover crop for fertilizer?
4) Can I skip fertile holes and just fertilize with compost tea during growing season?

Thanks for the input!

Hi Ariana,
I think that if you have easy access to lots of cardboard then using it would be faster and far easier than flipping sod. Both of those options are free, which is nice. I don't think topping cardboard with hay is necessary. It would look nicer though. I suggest that you start with the cardboard and then decide if you want something on it. If you overlap the cardboard it should be fairly wind resistant and might not need too many weights or pegs to keep it all in place.

For fertilizer - I haven't tried or researched the fertile holes idea but  top dressing just makes more sense to me. Oxygen helps the material break down aerobically and that doesn't happen as easily in a hole in the ground. Also, nature fertilizes from the surface and I like to follow her cues.

You asked about cover cropping - I don't really know how to achieve that while smothering the grass at the same time. If you leave the aisles as grass, you could over-seed that grass with clover to start fixing nitrogen.

If you've read my post this far you might have noticed I don't really know what I'm talking about. I'm just another guy on the internet with opinions. Anyways, good luck with your three sisters!

Welcome to Permies! You're come to a great place to find answers to your questions and share your projects.

I think you have excellent ideas, but whether or not your soil will be ready to plant by April will depend on the weather; this time of year, specifically, the temperature. It's the soil microorganisms that break down the materials to increase soil fertility, but in winter they tend to be dormant. So, stuff doesn't break down much in winter months. I live in zone 7b, and find that cardboard takes about a year to break down enough to need to replace it. Hay or straw take awhile too. I find dried leaves break down the fastest, wood chips the slowest.

A caution about using hay; if it contains grass seed you may be planting yourself a headache. Ask me how I know! If the hay was cut before flowering or going to seed, it should be fine. Straw is supposed to be seedless (remnants of harvested grain) so it's good too.

Your fresh green (nitrogen rich) materials will take awhile to break down as well. Again, especially in winter. The problem is, they require nitrogen to decompose, and so tie up soil nitrogen that your plants need. Well rotted manure would be a better option than fresh, if you can find it.

I know more answers and ideas are on the way. I hope you let us know what you end up doing and keep us posted on your progress.