Soil Testing: The Key To Better Vegetables

In the world of gardening, no experience equals the ecstasy of the moment when pulling a green-leafed stem. 

The gardener finds on end a fat red radish, a tender turnip, a beet, or a carrot! It seems akin to the mystery of creation.

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Whether we are backyard gardeners or thousand-acre growers, there is nothing more depressing or costly than a stunted radish too hot to handle, a flowering tomato plant minus fruit, or a beet whose woody cross-section reminds one of a fallen tree. 

Such failures too often are accepted as the “law of averages,” “old seed,” and “lack of rain.” 

We ignore the fact that from the partnership of soil, water and air came plant life in the first place and that to determine good or bad growth, we must return to these basic elements. 

There could be no life without any one of these. As a combination, they feed, clothe and shelter us.

Pollution Affecting The Soils

Raw chemicals and their compounds are being poured daily into the air, rivers, and oceans by factories, automobiles, aircraft, and other means. 

The air is polluted, the streams are polluted, and even the rainfall is polluted. The water we use is chlorinated and often fluoridated. This all ultimately results in affecting our soils.

Most gardeners understand that good soil is a living thing, teeming with micro-organic life essential to plants. 

They are also usually aware that soil organisms need air, so they keep their soil in good tilt to allow air to enter.

Soil Testing For Balance

Water is necessary at this point to dissolve usable nutrients, as plants all live on a liquid diet.

Science has demonstrated that the only way we can overcome man-made pollution of our soil is to turn to modern control methods. 

The key to this control is the soil pH, the acid-alkaline balance of the soil. Unfortunately, the only way we can intelligently determine pH is by testing.

However, it is difficult to understand the average gardener’s indifference to soil testing. 

Those who have taken our modern scientific advancements in stride accepted the automobile, airplane, radio and television, modern medical preparations, and vitamin pills. 

They still go into their gardens and literally pour everything in the book on their soil without the faintest idea of what is needed—or how much.

Some, perhaps, do not realize that nutrients in over-supply can be more destructive to plant life than the lack of them. 

They merrily douse here and douse there, saying, “If a little is good —a lot is better!” 

Others apparently feel that soil testing is just another unessential gimmick, another attempt to fatten someone’s pocketbook. Nothing could be further from the truth.

Commercial growers who depend upon production for a living spend thousands of dollars annually testing, correcting, and maintaining constant pH control. 

They do it because it means greater yield and better quality —exactly what the home gardener is after.

Influence Of H2O On The Soil

The only chemical formula we will consider is H2O (water) so that you may understand how it influences soil pH. 

When water enters the soil, a small portion of it ionizes, and H2O becomes H (hydrogen ion) and OH (hydroxyl ion). 

These ionized water ions unite actively with plant food elements, and the degree of acid-alkaline balance is directly proportional to the relative amounts of H and OH ions present. Hydrogen ions produce acidity—hydroxyl ions, alkalinity.

A mathematical scale has been established in soil testing to indicate relative pH (potential hydrogen). 

Figure 7 is designated as the neutral point where acid and alkali are in exact balance. 

Soils testing below 7 are increasingly acidic as the figure decreases; readings above 7 are increasingly alkaline as the figure increases. 

When you consult a vegetable pH preference list and find that beets and carrots prefer a pH of 7 ½, while chives and radishes need a pH of 6 ½, don’t arch your eyebrows and say, “What possible difference could one point make?” 

Remember that each point of the pH scale indicates a redoubled quantity; 6 indicates twice the acid of 7, and 5 indicates FOUR TIMES the acid of 7. 

The same ratio applies to the alkaline scale. So, even a half point can mean a wide variance in soil balance.

pH Preferences

The pH preference of most fruits and vegetables is as follows: 

pH 7 ½

The fruits and vegetables that prefer this pH level are:

  • Apple
  • Artichoke
  • Asparagus
  • Beet
  • Cabbage
  • Carrot
  • Cauliflower
  • Celery
  • Lettuce
  • Onion
  • Parsley
  • Plum 

pH 6 ½

The fruits and vegetables that prefer this pH level are:

  • Broccoli
  • Brussels sprouts
  • Cantaloupe
  • Cherries
  • Chicory
  • Chives
  • Corn
  • Crab apple
  • Cucumber
  • Eggplant
  • Endive
  • Garlic
  • Horseradish
  • Kale
  • Kohlrabi
  • Leek
  • Lima beans 
  • Mushrooms
  • Muskmelon
  • Okra
  • Peach
  • Pear
  • Pea
  • Quince
  • Eadish
  • Grape
  • Raspberry
  • Rhubarb
  • Rutabaga
  • Salsify
  • Soybean
  • Spinach
  • Swiss chard
  • Watercress
  • Watermelon

pH 6 

The fruits and vegetables that prefer this pH level are:

  • Apple
  • Bean
  • Blackberry
  • Buckwheat
  • Cowpea
  • Currant
  • Gooseberry
  • Lentil
  • Peanut
  • Pepper
  • Sorghum
  • Squash
  • Strawberry
  • Tomato
  • Turnip

pH 5 ½

The fruits and vegetables that prefer this pH level are:

  • Grape
  • Parsnip
  • Pineapple
  • Potato
    Sweet potato
  • Pumpkin

pH 4 ½

The fruits and vegetables that prefer this pH level are:

  • Blueberry
  • Cranberry

Essentials For Soil Testing

Within the indicated ranges, nutrients and microorganisms essential to the noted plants are found in the best supply and most active conditions. 

This is more vitally important to food plants than to ornamentals. To have fine-quality vegetables, fruits and berries, there must be no growth lag, the chief cause of woody root crops and runty, tasteless bush and vine crops.

In addition to improved quality and quantity, a sustained testing program brings extra benefits. 

Maintaining Soil Tilth

Soil tilth (crumb structure) is more easily maintained within a pH 6 to pH 8 range, with a resulting larger population of soil organisms. 

This means more available plant nutrients. It also prevents the lock-up of important trace elements. 

This way, you save money, as you need to apply smaller amounts of fertilizers, soil supplements, and water less often. Yet you produce higher vitamin content in the foods.

Considering the vast difference in soils from east to west and from north to south, it is obviously impossible to recommend specific corrective measures for any one area.

Solution To Soil Imbalance

The solution to any soil imbalance should be taken to your favorite nursery authority or garden center. 

Your local supplier has the correctly compounded fertilizers and supplements for your area. We do not hesitate to have a family counselor, be it a doctor or attorney; why not a soil counselor?

Now, as to the necessary equipment for soil testing. Many professional and amateur gardeners have turned to home soil test kits. 

These have no involved mathematical equations to work out; no knowledge of chemistry is needed.

Test Sample

Soil pH, nitrogen, phosphate, and potash needs are usually determined by a color comparison of the test sample, with a color card supplied in the kit.

You will find that soil constantly changes in pH and nutrient needs; therefore, tests should be made at least four times a year. 

About four hours of work per season will accomplish these tests even in a large area. Balance those hours against the savings in dollars and disappointment, and you will probably conclude that soil testing is a practical modern tool in vegetable gardening.

44659 by Floyd G. Laughton