What is the pH of that soil?
What is the base nutrient load?
Both are things you need to know before you start and the best way to find that would by with a soil test done by your states USDA Cooperative Extension Service. Dig also with these simple soil tests,
1) Structure. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. A good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

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 you 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 your soil is like now.

Kim's (very safe) answer is probably a good one here. If this were a little patch of your back yard and you just wanted to try a few veggies, a full battery of soil tests would probably be overkill.

But 10 acres is a considerable portion of land to manage, and you'll have to think big. A soil test is a good idea - SEVERAL soil tests from various parts of the property is an even better idea. Start there and see where that takes you.

Regarding building organic matter: Unless you have access to a massive amount of compost materials, manure and cover crops are gonna give you the most bang for your buck. You might also consider a longer term strategy where you devote a certain portion of the land to organic matter production, then harvest that OM for use as compost and mulch for the crops in the other part. The portion devoted to OM production will need to be pretty high... on the order of 60-70% of the land area.

Periodic application of manure feeds the grasses/grains - grasses/grains are then harvested for compost and mulch for crops.

It's a big undertaking - good luck!

-Diggity

I believe it was sweet clover that was commonly used for building soils because they grow deep roots quickly and the rotting roots put OM deep in the soil.
Not a believer in no-till however. Thousands of years of forest still only have 4 or less inches of good topsoil.
I need more evidence of the advantage. Tilling in annual grasses as 'green manure' works very well. 8" deep is really nice soil. Subsoilers have added production in this neck of the woods as well for many types of farms.

kim - yes i KNOW i need to get a soil test done. been procrastinating it. but i DO know that it needs organic matter. i live 1/4 mile from the arkansas river and my soil is almost entirely sand (i can run water on a depression for DAYS and have less than an inch standing. and when i remove the hose, it drains in minutes). there is a sand pit on the same 1/4 section as me even. i have a degree related to botany, and minors in hort and agron, so i know how to determine the soil quality. my questions are about improving the soil quality with organic matter, particularly root crops.

dig - i am going to try all of the common stuff as well, using cover crops and manure when i can find it. i plan on keeping most of it in alfalfa like i said, to provide the bulk material for my sheet mulching. i have chickens, so will have some manure from them as well as a boost for breaking down the sheet mulch.

axe - the reason i want to do those root crops is for the amount of OM they put deep in the soil. some of those roots go down 12 inches. and if i had a fibrous rooted legume planted with them, the amount of OM in the soil would be substantial. one reason i want to go with primarily no till, is because the land was unbroken until this spring and the weed seeds are PLENTIFUL. i have done my research and it seems sheet mulching will be the best option for covering those seeds, and preventing them from germinating. i'm trying an area this fall, and will see how it does next spring. this isn't the best application of sheet mulch, but it will give me a better idea of if it will work. i sorta did it in one spot in my orchard where i just dumped all of the leaves from last fall, and planted some tomatoes there this year and they have no weed competition, they are 3 times the size of my other tomatoes, i havent watered them yet, and they have produced TONS more tomatoes compared to my other plants. that kinda sold me on the sheet mulching idea.

to give you an idea of how weedy my site is here is the list of dominant species as they appear on my property (seasonal succession): geranium maculatum, bromus tectorum, aegilops cylindrica, digitaria sanguinalis, sonchus oleraceus, setaria glauca, conyza canadensis, and ambrosia trifida. with a little bit of amaranthus palmeri and retroflexus, chenopodium album, solanum rostratum, and abutilon theophrastii for good measure. there is also some weedy mirabilis species, that i have yet to determine what it is. it has a MASSIVE taproot, and that is the only species i know i will have trouble with when sheet mulching. the rest i think will be taken care of. WHEW! enough of that weed tangent!! i am trying several methods to control the weeds, but if i cant find a solution that works well, i will pose that question to you guys at a later date.

so again, has anyone used root crops as a method of building soil organic matter?

Now that we know that you are somewhere along The Arkansas River we can be a bit, still not much, more specific about what to do. Most likely your friends and neighbors around throw away tons of organic matter every year that you could use in addition to the cover crops. The decidous trees around the area produce a lot of organic matter that is more often than not simply thrown away.

Though you have sandy soil, it sounds like you may also already have some fertility in the soil with the abundance of weeds you list. Good luck in your research, it sounds like you already have a jump on it. I'm interested to hear how it goes, what you find out. Perhaps you can do a trial patch the way you are planning if you can't get more information from "experts" on the subject.

Yeah, it sounds like you've got a pretty clean canvas and the knowledge to paint something beautiful there. Please do let us know how it goes. And we LOVE pictures, if you haven't figure that out already. :-)

RE: root crops as a soil builder. To be honest, this is one thing I have never really tried (unless you count legumes, but I think you're referring more to beets, mangels, radishes, etc). I've heard of the technique before - I think John Jeavons is a proponent of it. Something in the back of my pea brain tells me its one of those things that sounds great on paper, but falls short of expectations in real life. But again, I say that with NO hard experience in the matter, so don't listen to me.

-Diggity

I have heard of people using potatoes as a first crop to "soften" up the soil for later digging but that doesn't really sound like what you are planning.

kim - yeah, i'm collecting from friends and family and stuff, but i like 40 miles from everyone i know. and my closest neighbors are farmers that are 1/2 mile away (and they are not very friendly to the new young "organic" farmer in the neighborhood). so i get as much as i can from other people, but still not getting enough. i am putting up a sign for the driveway that says WANTED: spoiled hay, grass clippings, leaves, wood chips, manure, and other organic matter. with an arrow pointing to where to dump em (and a number to call if they want me to come get em).

tclynx - i do plan to do a trial patch, even if people say its not gonna work. its worth a shot at least, even if its a small area. as for potatoes, not really what i'm going for. i could leave them in the ground, but they are WAY more labor intensive than the other species listed. so it would be sorta overkill for what i'm trying to do. as for the fertility and weeds, all of those species can live on basically nothing. their nutrient inputs are VERY low, so they dont necessarily need a whole lot of nitrogen.

dig - i will check into jeavons, and see if i can find any info he has published on that topic. thanks! as for legumes, i plan to do those as well, because i know i need nitrogen. and if i plant all of those hungry root crops, they will be wanting nitrogen.

i will get some pics this fall, when everything is brown so you cant see how bad the weeds were, haha :).