Thank you for the info & link. Justaguy, you might want to reconsider your position on nematodes, as I did apply them this spring, and I am certain they made quite a difference, by comparing my garden to that of my neighbors. Kissmsr, I thank you for your diligent reply to many posts on this forum. I have gained much knowledge from reading this forum over the past few months, & you seem to have many of the answers. I among many others have benefitted from your experience, though i wonder how you have the time to do it all!

If you're just looking to improve the soil and not attack certain pests within it then if I were you I'd focus on using compost, green manure crops and real manure (unlike what Sue says, compost does add nutrients and green manure crops if they're legumes or clover add nitrogen affixed from the air and also pull up nutrients that have leached further down in the soil--alfalfa is good at pulling those up and nitrogen fixing, mustard isn't nitrogen fixing but gets deep tap roots that pulls up minerals from deep down. There are other plants like acacia and mesquite trees that are nitrogen fixing as well (pretty much anything that gets a pod w/ seeds or beans is nitrogen fixing). Adding mulch, which would be difficult to do on a large scale farm, would improve the soil by encouraging the growth of microorganisms and worms along with possible nematodes if any still exist in the soil...I'd wait until the soil is greatly improved and kept moist until bothering to buy nematodes or you'll just be wasting your money for sure. Worms are better at improving the soil than nematodes--nematodes just kill bad bugs that live in the soil or lay eggs in the soil--so that's the only way they improve it. If your soil is sandy and dry you might want to consider water crystals that are not sodium based, they'll last up to 20 yrs depending on conditions and retain water and nutrients that you apply (fertilizer), they also mechanically improve soil tilth by expanding and contracting as they absorb and release water, this helps aerate the soil. There's a kind of ground rock shale (forget the name) that's said to imrpove the soil as well, it can be applied dry or mixed with water like a tea, it doesn't add much nutrients but instead helps release nutrients locked in the soil w/o affecting pH too much and suppposedly encourages soil life to develop, it's kind of questionable--wood ash would probably be as affective but does alter pH. but since you're talking about large farm land acreage I would focus on green manure crops--any cow or chicken manure you can obtain, you might have to use artificial or natural fertilizers on the green manure crop. I'd also seriously consider investing in the water crystals, just not the kind that degrades into salt, there's a kind that degrades into nitrogen or potassium (forget which I think potassium) after 10-20 yrs and will greatly improve water & nutrient retention--you can even soak them in fertilizer water before applying. They're fairly inexpensive if bought in bulk on Ebay from a reputable seller. You can make a desert bloom with the stuff!

Let's start with ... Smuggling is never good. The African bee is one of just a long list of accidents or well intended species introductions to North America that have gone 'bad'. Nematodes, by continent origin. I think we have to respect as well. Many may be microscopic, but even at the microscopic have a way of effecting the world around us. Wikipedia: Nematode: Anatomy: "Nematodes are slender worms: typically approximately 5 to 100 õm thick, and at least 0.1 mm (0.0039 in) but less than 2.5mm long. The smallest nematodes are microscopic, while free-living species can reach as much as 5 cm (2.0 in), and some parasitic species are larger still, reaching over a meter in length. The body is often ornamented with ridges, rings, bristles, or other distinctive structures." As slugs have a range in size; so do nematodes it seems! Peter Kelley St. Paul, MN USA

Nematodes are soil critters. Are the bugs bugging you soil bugs or bugs that spend part of their life in the soil you would treat? If your answer to these questions is 'no', then the nematodes won't do you any good.