If you find that certain plants do<br >poorly regardless of care， or the<br >whole garden grows too slowly，<br >looks stunted， and has a high mor-<br >Acidity<br >Acid soil is at the other end of the scale<br >from alkaline soil. It is most common<br >in areas of heavy rainfall and is often<br >associated with sandy soil (but ocean<br >beaches are rarely or never acid). Soils<br >high in organic matter tend to be acid<br >rather than alkaline.<br > Mildly acid soils cause little trouble，<br >and some plants--azaleas， rhododen-<br >drons， and camellias， to name a few--<br >prefer soil that is moderately acid. But<br >for most plants an intense acid condi-<br >tion is highly undesirable.<br > When a test indicates that soil is<br >acid， adding liming materials will help<br >to neutralize it， since all acid soils are<br >low in calcium (lime). Fertilizers can be<br >another very important factor in con-<br >trolling acidity: some fertilizers can ac-<br >tually increase soil acidity.<br >means the only ailments to occur，<br >but they are common ones that<br >home gardeners should be aware<br >of.<br > Nursery personnel， experi-<br >I~.i~ ~ enced local gardeners， and agricul-<br > tural extension agents can be help-<br > ful in testing or evaluating your soil.<br > You could also get a detailed anal-<br > ysis from a commercial laboratory<br >tality rate， examine the six soil or use a do-it-yourself soil testing<br >problems and solutions discussed kit. The kits are widely available and<br >below， will give you a good idea of the<br > These soil problems are by no status of your soil.<br >Alkalinity<br >Alkaline soil， common in light-rainfall<br >areas， is soil that is high in calcium<br >carbonate (lime) and certain other min-<br >erals. Many plants will grow well in a<br >moderately alkaline soil， though camel-<br >lias and other acid-loving plants will not<br > Gardens in which softened water is<br >used are quite likely to have alkaline<br >soil.<br > Gypsum may be useful in some<br >alkaline soils; iron and sulfur benefit<br >moderately alkaline soils. Since large-<br >scale chemical treatment of extremely<br >alkaline soils is expensive and complex，<br >it might be easier to plant in improved<br >soil in raised beds and containers.<br >Nutrient deficiency Salinity<br >Most soils， left alone， yield the three<br >major plant nutrients--nitrogen，<br >phosphorus， and potassium--very<br >slowlv.<br > Fertilizers， either chemical or or-<br >ganic， are the quickest and easiest an-<br >swer to a nutrient deficiency. Many<br >complete fertilizers， containing all<br >three major elements， are available (see<br >the chapter on fertilizing techniques<br >beginning on page 29). There are also<br >formulations of nitrogen， phosphorus，<br >or potassium compounds that provide<br >these nutrients separately. Organic<br >amendments and soil conditioners are<br >also beneficial in varying degrees<br >An excess of salts in the soil is a wide-<br >spread problem in arid and semiarid<br >regions. It can prevent germination; or<br >if plants are already growing， it stunts<br >them and in advanced cases burns their<br >foliage and finally kills them. Its pres-<br >ence can usually be detected by white<br >deposits of salt on the surface of the<br >soil. Frequent and shallow watering<br >(especially with softened water)， as well<br >as use of certain fertilizers， can cause<br >salts to build up. Periodic slow， deep<br >watering will help wash the salts beyond<br >roots (if there s no compacted soil).<br >Chlorosis<br >Chlorosis is a plant condition fre-<br >quently caused by the inability of plants<br >to take in iron from the soil through<br >their root systems. If the deficiency is<br >mild， areas of yellow show up between<br >the veins of the leaf; if the deficiency is<br >severe， the entire leaf turns yellow.<br > Iron deficiency in the plant is only<br >occasionally the result of deficient<br >amounts of iron in the soil; more fre-<br >quently it is the result of some other<br >substance (principally lime) that ren-<br >ders the iron unavailable. Sometimes<br >chlorosis results from magnesium de-<br >ficiency， even when iron is present.<br > Chemical treatment of the soil with<br >chelated iron or iron sulfate can cor-<br >rect chlorosis. You can treat plants with<br >serious iron shortages by spraying foli-<br >age with a special iron solution.<br >Shallow compacted soil<br >A tight， impervious layer of soil can give<br >trouble if it lies at or near the surface.<br >Such a layer--known as hardpan--<br >can be a natural formation or it can be<br >manmade. Roots cannot penetrate the<br >hard layer， and water cannot drain<br >through it.<br > If the hardpan layer is thin and if<br >your garden plot is accessible to heavy<br >equipment， you may be able to lessen<br >or eliminate the problem by having the<br >soil plowed to a depth of 12 inches or<br >more. If this is impractical， you can<br >drill through it with a soil auger when<br >planting. If the layer is too thick， you<br >may want to have a landscape architect<br >help ~ou with a drainage system， which<br >mighl~volve sumps (side or bottom)<br >or d~h tiles. Or you can switch to<br >raise[t beds and container gardening.<br >Understanding Your Soil 5<br ><br >