Subsoil Drainage Test:
Dig a hole in the garden about 12 inches deep and the diameter of a spade. Pour water in the hole to the rim. Refill the hole a day later and observe how long it takes for all the water to soak in. If the water soaks in within a few minutes, the subsoil drainage may be too good. Such soils may not hold enough water to sustain plant life and can lose valuable nutrients through leaching. If the water takes more than one hour to soak in, the subsoil drainage may be poor. Plants may suffer from oxygen starvation (drowning) under these conditions.
Roll some slightly moistened soil between your thumb and forefinger. If it forms a firm ball, feels smooth and becomes sticky when moistened, it is too high in clay. If you cannot form a ball, the soil will not stay together and it feels somewhat grainy, the soil is a better mixture. If, on the other hand, the soil feels very coarse, it may be too sandy and will not hold an adequate amount of water.
Soil improvement is a continual process.
If your soil is too sandy or too high in clay, the solution to both extremes is to add organic matter. It is possible, especially in clay soils, to create a soluble salt problem by adding too much organic matter all at once. The general “rule of thumb” is to incorporate no more than 3 cubic yards of organic matter per year. This is equivalent to 1 1/2″ of amendment on the soil surface before it is tilled in. All amendments added should be thoroughly tilled into the soil, making it a uniform mixture.
Gardeners who are patient, know how to select plants that will do well, and manipulate the soil and micro climate, will be amply rewarded.