I guess I don't understand regarding sand over manure for improving tilth. Doesn't organic matter well in excess of that amount needed for fertilizer alter clay soil structure in a positive way, making it loamy? That has been my experience: pure red georgia clay well tilled with enough poop is crumbly loam. If so, whats the point of sand? Is it that both clay and organic matter will hold water, and sand won't, which helps soil to drain better, and to crust over less? That is one thing I've noticed, no matter how much poop I add, my soil still crusts after a rain. Can sand address that? If so, I might try a bag of sand in one area. Would a bag of play sand in one area be appropriate?

In case the link is ever broken, cut and paste the PDF file here: Linda Chalker-Scott, Ph.D., Extension Horticulturist and Associate Professor, Puyallup Research and Extension Center, Washington State University The Myth of Gypsum Magic âAdding gypsum to your yard or garden will improve soil tilth and plant healthâ The Myth Upon continued prodding from one of my university extension colleagues, I recently watched several episodes of a well-known gardening program on television. My kids joined me, alerted by my animated responses to the hostâs non-stop torrent of advice. Among many amazing discoveries I learned that by adding gypsum to my yard or garden I would improve my problem soils by changing the particle size and loosening compaction. Further searching on the web revealed that gypsum would also improve drainage, decrease acidity, and eliminate soil salts. Previously, I had heard of gypsum for use in soil reclamation projects, but not for a typical urban landscape. Since gypsum is simply calcium sulfate, could this chemical truly transform soil structure and serve as a fertilizer for yards and gardens? The Reality This myth falls into the category of agricultural practices misapplied to ornamental landscapes. Gypsum effectively changes the structure and fertility of heavy clay soils, especially those that are heavily weathered or subject to intensive crop production. Gypsum also improves sodic (saline) soils by removing sodium from the soil and replacing it with calcium. Therefore, one can see improvement in clay soil structure and fertility, and desalinization of sodium-rich soils, by using gypsum. What other effects will gypsum have on soil and plant health? There are a number of scientific studies on gypsum usage both in the literature and on websites. Briefly, researchers have found: ⢠Gypsum does not usually change soil acidity, though occasional reports of both increasing and decreasing pH exist; ⢠Gypsum can increase leaching of aluminum, which can detoxify soils but also contaminates nearby watersheds; ⢠Gypsum can increase leaching of iron and manganese, leading to deficiencies of these nutrients; ⢠Gypsum applied to acid soils can induce magnesium deficiency in plants on site; ⢠Gypsum applied to sandy soils can depress phosphorus, copper and zinc transport; ⢠Gypsum can have negative effects on mycorrhizal inoculation of roots, which may account for several reports of negative effects of gypsum on tree seedling establishment and survival; ⢠Gypsum is variable in its effects on mature trees; ⢠Gypsum will not improve fertility of acid or sandy soils; ⢠Gypsum will not improve water holding capacity of sandy soils; and ⢠Gypsumâs effects are short-lived (often a matter of months) With the exception of arid and coastal regions (where soil salts are high) and the southeastern United States (where heavy clay soils are common), gypsum amendment is just not necessary in non-agricultural areas. Urban soils are generally amalgamations of subsoils, native and non-native topsoils, and - in home landscapes - high levels of organic and non-organic chemical additives. They are also heavily compacted and layered (and gypsum does not work well on layered soils). In such landscapes, it is pointless to add yet more chemicals in the form of gypsum unless you need to increase soil calcium levels. This nutrient deficiency can be quickly identified by any soil testing laboratory for less than a bag of gypsum costs. (If you need to improve sulfur nutrition, itâs wiser to use ammonium sulfate). To reduce compaction and improve aeration in nearly any landscape, application of an organic mulch is more economically and environmentally sustainable. The Bottom Line ⢠Gypsum can improve heavy clay soil structure and remove sodium from saline soils ⢠Gypsum has no effect on soil fertility, structure, or pH of any other soil type ⢠Most urban soils are not improved by additional gypsum ⢠Before adding gypsum or any chemical to a landscape, have soil analysis performed to identify mineral deficiencies, toxicities, and soil character ⢠Adding gypsum to sandy or non-sodic soils is a waste of money, natural resources, and can have negative impacts on plant, soil, and ecosystem health For more information, please visit Dr. Chalker-Scottâs web page at http://www.theinformedgardener.com.

Lots of good replies here. In a nutshell: Sand is weathered rock. Tiny little pieces of rock, broken down by wind and rain and erosion. Silt is weathered sand. These are primary minerals, broken down rock. Clay is different. Clay is a secondary mineral, created from the chemicals given off by sand and silt as they break down into smaller particles through exposure to acids like acid rain or organic acids. Clay particles are tiny plates that fit together very tightly and are attracted to each other by electrostatic charges. Time is the main difference. It takes longer for clay to form than either of the others. Sand, silt and clay are moved around by wind, water and ice. Vermont is rocky because it was scraped bare by glaciers and has not had time yet to develop new soil. Same thing where I am, in the Puget Sound area which was carved out by glaciers. Our soil is what the glaciers dumped as they melted off after carving out Puget Sound and the Strait of Georgia and Hood Canal. It's like gardening in aquarium gravel. Rocks, gravel and sand. No organic matter. I wish I had clay. The river valleys have really nice loamy soil, because they get what's washing down off the mountains - organic matter from the forests, clay from weathering, volcanic ash off Mt Rainier and Mt St Helens etc, and not least, thousands of dead salmon every fall. Migrating salmon returning from the oceans, going up the rivers, spawning and dying and washing up on the banks. The best fertilizer on earth. Prairie soils develop when thick grasses trap wind blown silt and clay. A nice loamy mix of organic matter and soil. Clay soil is what it is. Best to learn to work with it, not against it. You can't change it, only replace it in small areas. Organic matter disappears because the soil microbes eat it. The sand disappears because it gets lost in the clay matrix and sets like concrete. Clay soil is much more fertile than what I have. Clay particles have a very large surface area to volume ratio, so nutrients have lots of surface area to stick to, and stick they do because clay particles are electrostatically charged. In my gravelly soil nutrients wash right through, there's no clay or organic matter for them to stick to. Sand and gravel have no electrostatic charges. All you need to do is add compost and mulch every year. If you have a good worm population they'll work it in. When I had clay I did dig in organic matter whenever planting something not native to the area, and then mulched every year. But if you add a lot of amendments to a hole in clay, you're just creating a clay pot and the plant can drown because water won't drain from the amended soil into the clay. Just add a little bit in a big hole.

When was the last time you had a good, reliable soil test done? What is your soils pH? What is the nutrient load in that soil? How well does that soil drain? How well does that soil retain mosture? What life is in your soil? Contact your Universtiy of Georgia USDA Cooperative Extension Service county office about having a good reliable soil test done and also dig in 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 you do have for soil and what you need to do to make it better.