To re-wet, repeatedly sprinkle the surface lightly, making sure there is no run off. Covering the surface with a mulch such as straw, leaves, wood chips, or compost will also help. Eventually the soil will become moist enough to break up. A gentle, steady rain will also do the trick.
To dry out soil quickly, you can apply hydrated lime to the soil, add compost and then turn the soil thoroughly to aerate it. Adding hydrated lime and compost will help absorb the water in your soil, and turning it all will help distribute the water in the waterlogged soil throughout your garden.
Use soil wetting products and organic matter
These products, available in granular, liquid concentrate or hose-on form, can dramatically improve water penetration. “Soil wetting agents help by penetrating through the waxy layer, enabling water to be absorbed throughout the soil,” she explains.
To re-wet, repeatedly sprinkle the surface lightly, making sure there is no run off. Covering the surface with a mulch such as straw, leaves, wood chips, or compost will also help. Eventually the soil will become moist enough to break up. A gentle, steady rain will also do the trick.
If the soil is hard because its dry and compacted, I would moisten the soil. Water it, let the water soak in, then water again, and repeat until the soil is deeply moist but not so much that water pools on the surface. Let it sit for a day. Any soil when moist is workable.
Add Water
For old and dry soil that isn't compacted, add water to a pot of soil and let it drain out from the bottom.
Dry soil can be easily improved by adding organic matter, such as well-rotted manure or garden compost. This will improve the soil structure and will help to retain moisture.
Lime is highly effective at increasing soil pH in acidic soils. Even small applications can increase pH by 0.5 to 1 unit. The degree of change depends on the soil's buffering capacity. Soils with low cation exchange capacity (CEC) will see greater pH increases from liming.
If your soil has already become waterlogged, you might not be able to save the plants, but you can fix the soil and drainage to avoid it happening in the future. Once conditions are dry again, amend the soil by adding organic material to break it up and improve drainage.
Create a healthy soil habitat (pH, soil structure, organic matter) to promote beneficial soil microbes. Building organic matter, maintaining optimal pH, and managing deficiencies in critical nutrients such as nitrogen, phosphorous, and sulfur are important for both your plants and soil microbes.
Soil may also become hard due to lack of water, rocky composition, or excessive foot, equipment or vehicle traffic. Over-tilling, working soil when it is sodden, and mixing sand into clay soil in an effort to lighten it can all contribute to compaction, resulting in soil that is hard and difficult to work.
Restoring good vegetation to degraded soil helps to maintain its structure, as the roots become strongly anchored, generating a cycle of organic matter that can help to restore fertility.
Organic amendments like compost, manure, and peat moss have high water-holding capacity, acting as sponges that absorb and slowly release moisture to plant roots. Inorganic additives such as vermiculite and perlite create reservoirs within the soil, absorbing and holding water for plant uptake.
Top-dressing planting beds with several inches of compost will improve lightly compacted soils. Earthworms and other soil fauna will gradually pull it down into the soil, loosening it and improving water-holding capacity. A 2- or 3-inch layer of shredded leaf mulch or wood chips will provide similar benefits.
“Another option for gardeners who have larger containers is to remove only the top 6 inches or so of the old potting soil and replace it with new potting soil,” he said. “Since they aren't replacing all the soil, they're saving money while still refreshing the upper area, which will aid in root growth.
Compost is the best substance to mix in with hard soil.
Some other materials you can mix in include grass clippings, straw, manure, sphagnum moss, or leaf waste. If your soil has a lot of clay, mixing in some coarse sand can help improve the hard texture, too.
Simply add organic debris to the soil surface and let your “underground herd” break it down. As it does, it will improve your soil's texture and make nutrients available to your plants. So don't be shy about applying copious amounts of organic residue to your soil.
Gardeners, remember that organic matter freshens used potting soil. This can be accomplished in several ways using soil amendments, such as humus, worm castings, vermicompost, composted livestock manure, decomposed compost, mushroom compost, leaf mold and others.