How to thicken grass in large ~4-5 acre "yard"?

Question

I have a 4-5 acre area that I converted from corn/soy field to grass around 8-10 years ago. One end is VERY sandy soil, the other isn't. It's a gradual change over ~1,000ft length.

I've used broadleaf killer every other year (sometimes every year) and used crabgrass preventer + feed this year. I've also over-seeded twice, though without any tilling/prep of the surface.

From a distance, it looks good:

But when looking closely / walking on it, it's quite sparse:

The grass has never completely filled in / has always been sparse. It's definitely more sparse in the sandy areas.

What can I do to help promote grass growth to give make thicker grass to look/feel better and and hopefully crowd-out some of the weeds? If it were a small yard, I could probably come up with solutions, but at this scale, I'm just not sure.

I have a large mower available, and can tow a small sprayer or spreader, but I don't have a tractor.

Answer 1

At that scale, you're either spending a ton of money on typical lawn approaches, or you move to farming approaches.

i.e. haul a LOT of finely ground organic material in from somewhere else and spread it very thinly over the grass so as not to bury it, repeatedly...

Or

Grow cover crops and till them in to build up organic matter. Yes, that involves it not being "4-5 acres of not very happy lawn" for the time period when you are correcting the deficiencies by growing "green manure" crops to sheet compost. For that matter, if you commit to that course, you can pile on a bunch of the other sort of manure, if available locally, before tilling the grass under and planting the cover crop. You might want to pay for a neighbor with appropriate equipment to do the tilling efficiently. You might want to do several iterations of cover crop and tilling under before going back to grass.

If you can accept clover in your lawn that helps to build nitrogen naturally, and fills in well, but if you are a "grass-only" person (or a "lawn weedkiller" person) that won't work for you.

One other approach that might help is to raise your cut - taller grass has deeper roots - if the soil is sandy and does not retain water well, cutting the grass short will make it much more prone to drying out.

Answer 2

One gardener's weed is another gardener's wildflower. I'm assuming you're not managing sports turf, so why go to all that trouble killing weeds? Those self-sown plants are the ones that nature is telling you are best suited to your site. Stuff that self-sows and thrives in the sandy area, for example, will automatically be suited to those conditions, which is rather neat. You have a fantastic blank canvas there both for planting and to manage different areas using different mowing regimes, including a network of mown paths. Invest in a wildflower guide so you can identify what pops up. Try googling "wildflower meadows" or "wildflower meadows trees", etc for further inspiration.