“But you have such wonderful soil” is the envious complaint of the novice gardener to the seasoned landscape and garden veteran.
With this, the beginner discounts the foresight, skill and work that went into developing that “wonderful” soil. Chances are it was very poor in the beginning, probably no better than the soil the novice now has.
It’s wonderful indeed to have a nutrient rich soil, but no more so than to play an active, intelligent part in transforming a piece of comparatively poor ground into a mellow, fertile soil patch of garden. That is, perhaps, the highest gardening achievement.
I feel rather sorry for the gardener who has always worked rich soil. He has missed the great joy of making good soil from poor, of bringing one small patch of earth to a condition better than that in which he found it.
Almost Any Soil Can Be Improved
Fortunately, almost any soil can be improved and made suitable for gardening even stubborn, infertile subsoil. Know-how and time, plus work and various additives, are all that are necessary.
Don’t expect to do it with fertilizers, chemical fertilizers or chemical soil conditioners and other additives alone. Even in this high tech age, time and effort are also necessary.
Soil Chemically – Physically – Biologically Satisfactory
Good soil must be satisfactory in three ways:
Chemically it must contain adequate amounts of essential nutrient contents, be of suitable acid-alkaline reaction and free of substances toxic to plant growth.
Physically it should be of such soil structure that water drains through and air gains ready admittance, but not so loose that it does not retain enough moisture and nutrients for the plants’ needs;
Biologically it should contain an abundance of favorable bacterial and other helpful soil organisms and a minimum of harmful ones such as nematodes. Biological improvement naturally follows betterment of chemical and physical conditions.
Fertilizer the Fuel and Easily be Added
Fertilizers are easily added. Lack of one or more is the least of the gardener’s difficulties. They can be purchased in various forms and proportions under numerous trade names.
On each container is an analysis consisting of three numbers. These, in the order given, indicate the percentages of the three most frequently needed nutrients – nitrogen, phosphus and potash the fertilizer contains. They do not indicate the form in which the nitrogen is, and that is important.
Nitrogen is still nitrogen, whether derived from organic material sources or synthetic sources.
Old-time synthetics, however, such as urea, nitrate of soda and sulphate of ammonia, are highly soluble and quickly available; therefore, they are soon lost from the soil by leaching and other means even though they provide quick results in plants over a short period of time.
Organic nitrogen is much more slowly available. Synthetics derived from urea and formaldehyde have been developed that release nitrogen slowly. Often the best fertilizer to use contains both slow-acting and readily available sources of nitrogen.
All Garden Plants Need Fertilizer
Fertilizer is needed by nearly all garden plants. Its exact analysis is less important than beginners think. A good general complete fertilizer (NPK for nitrogen, phosphorus, potassium) such as a 5-10-5, 10-6-4, 4-8-4 or the like is satisfactory for most purposes, and it’s cheaper to buy a substantial amount of one kind than small lots of many.
For acid-soil plants, such as rhododendrons, azaleas, leucothoe, blueberries and heathers, use only acid or neutral fertilizers, not alkaline ones.
Fertilizer applications only pay off well when the soil is in good physical condition.
Nearly always the addition of a complete fertilizer (one containing nitrogen, phosphorus and potash) is beneficial when the ground is being made ready for planting and, in the case of permanent crops such as trees, shrubs, evergreens, lawns and perennials, each spring just when new growth begins and, usually, again in early fall.
These applications may be supplemented with one or more shot-in-the-arm treatments of quickly available plant nutrients during the summer growing season. Either dry or liquid fertilizers may be used. Remember, little and often is better than more widely spaced heavier applications.
The pH Factor
The pH factor of particular plants is talked about less today than twenty years ago, and for good reason. Most plants have a wider range of tolerance than many people believed and the vast majority of garden kinds thrive if the pH of the soil is between 6 and 7 or even slightly above 7. Some tricky acid-soil plants need reactions between pH 5 and 6, but they are for specialists.
Have your soil tested by your county agricultural agent, private soil-testing service or do it yourself with one of the advertised soil testing kits.
Correcting Acid or Alkaline Soil
Excessive acidity can be corrected by applying hydrated lime or ground limestone, preferably the latter. Excessive alkalinity is more difficult. Best results are had from mixing acid organic materials, such as peatmoss, in liberal amounts.
Acid fertilizers such as cottonseed meal also help. The addition of sulphur acidifies the soil and so does aluminum sulphate. Consult a garden soil specialist regarding the amounts of these to apply to change the soil reaction appropriately.
Improving the physical condition calls for more skill and work than does providing nutrients. It may involve draining, adding bulky soil organic matter, lime, gypsum and other correctives, the use of synthetic soil conditioners and most surely, turning the earth deeply.
Under the Soil Hood
Before embarking on a program, become familiar with what’s under the surface. In various places dig holes a couple of feet deep to check drainage. If water lies within 18 inches of the surface for several days drainage is faulty.
This may be because a thin layer of impervious clay overlying porous soil is holding water, in which case breaking through it by deep digging, deep plowing or dynamiting (just kidding) will correct the condition. More probably, the entire soil below the level of the water in the test holes is waterlogged. Then the installation of a system of agricultural drain pipes is called for.
Turning the soil deeply is of immense benefit. It brings to the surface new soil which is acted upon favorably by weathering agents. It permits the incorporation of bulky organic matter with the under layers. It loosens heavy soils, improves drainage and admits air.
Deep spading, plowing or tilling are especially beneficial on heavy (clayey) soils. The best time to turn over clay soils is in the fall. Leave the surface in rough clods because alternate freezing and thawing has a wonderful, ameliorating (to make better or more tolerable) effect on such soils. Don’t walk on or work clays when they are wet.
Add Large Amounts of Organic Matter
Unless your soil is muck, peat or another soil type derived largely from plant decay it will benefit tremendously if you mix in large amounts of decayed natural organic material. This is where a home compost pile pays dividends.
The humus this provides benefits clayey soils by keeping the pore space loose and granulated; sandy and gravelly soils, by holding moisture and nutrients. Organic matter becomes food for soil organisms and, as it decays, supplies nutrients for plants.
Securing sufficient organic matter is a serious problem. Excellent sources are animal manure, compost, sedge peat (commercial humus), peat moss and leafmold.
There are additional sources such as spent hops from breweries, seaweed and well-rotted sawdust. By and large, anything that has lived may, after death, be converted into humus. An organic matter filled compost pile is invaluable.
Get all the organic matter you can and mix it with the soil as deeply as possible. In the soil, use only well-rotted material in the spring and summer. In fall, half-decayed and even rawer material may be incorporated with it.
Organic Green Manure
Organic green manuring is an inexpensive way of adding humus.
It can be done whenever land is free of garden plants for a few weeks for instance, after vegetable plots and annual beds are cleared in fall and before any new garden is made.
“Green manuring,” of course, means growing cover crops and turning them under as soon as they are 6 to 8 inches tall. The tops and extensive roots rot in the soil.
For fall sowing, winter rye is excellent. Summer green manures most suitable for gardens are buckwheat, Italian rye-grass (this makes a first-rate temporary lawn if mowed and its roots still add humus when it is turned under), cowpeas and soybeans. Fertilize each crop; the plants take up the nutrients and later return them to the soil as they decay.
Lime is used not only to correct acidity but also to improve the texture of clayey soils. This it does most effectively. Use ground limestone or hydrated lime in amounts that will not cause the soil to become too alkaline (a soil test will determine this).
Since lime leaches out, applications every two or three years are likely to be needed. Lime helps also by providing calcium and releasing other plant foods stored in the soil in forms unavailable to plants. Where clayey soils need improving and you do not want to make them more alkaline, use gypsum (calcium sulphate) instead of lime (calcium carbonate).
Improvement of Clay Soil
Permanent clayey soil texture improvement will also result from mixing in fine coal cinders (not dusty ash but gritty soil particles) in proportions up to one third by bulk. Coarse sand is sometimes used, but better try this in a small way first; with some clays, sand in the right proportions forms a kind of concrete which is worse than the original clay.
Synthetic soil conditioners may preserve for several years the improved clayey soil structure brought about by spading, adding organic matter and other means. Results reported by gardeners following the use of soil conditioners vary widely. Try them in a limited area first and then be guided by the results.
A limited application of the practices outlined will bring some improvement but for the best results they must be persisted in and some, such as deep turning over, adding organic matter, fertilizer and perhaps lime, must be repeated regularly over a fairly long period to really do a first-class job.
With a poor-to-fair soil to begin with very noticeable gain will be made in a year. A very poor soil may be made quite good in two years, improving the water-holding capacity, and within three or four it can be made so excellent that again you will hear: But you have such wonderful soil.