The pH level, major and minor chemicals (fertilizer elements or nutrients), are invisible. That is the reason that samples of the garden soil should be tested every three years after the crop is harvested and the residue removed. Gardening with improper levels of soil pH can result in a poor yield of crops and the occurrence of some of the diseases.

The basic definition of pH is the relative degree of acidity or alkalinity of all substances with moisture. It is a chemical value of natural conditions.

A number from 7 to 14 pH is a chemical value that indicates alkalinity, and from 7 to 0 pH is acidity. The 7 pH substance is neutral. One number is 10 times different than the one next to it and two numbers are 100 times more.

The ideal soil pH values for Brazos County vegetables are: Potato, 4.5-6.0; Peanut, 5.0-6.5; Sweet Potato, 5.5-6.0; Melon, 5.5-6.5; Carrot, Corn, Pepper, Turnip, 5.5-7.0; Cauliflower, Cucumber, Garlic, Pumpkin, Tomato, 5.5-7.5; Broccoli, Eggplant, Lettuce, Onion, Radish, 6.0-7.0; Bean, Beet, Brussels Sprouts, Cabbage, Kale, Kohlrabi, Mustard, Pea, Spinach, 6.0-7.5; Asparagus, 6.0-8.0.

Extremes in pH affect the availability of plant nutrients and the concentration of the toxic minerals in the soil. In highly acidic soils (low pH), manganese and aluminum can concentrate at toxic levels. Low pH values also make calcium, phosphorus, and magnesium less available. At pH 7 and above, phosphorous, iron, copper, zinc, boron and manganese become less available for plant use.

Then improve the soil for the next crops by applying the amendments according to the soil-test report.

Guides to adjust the acidity or alkalinity level of the soil for the crops to be grown. If the pH level is known, use the appropriate table below to improve the pH level.

Table 1. Pounds of sulfur needed to lower your soil's pH

Change in Pounds of sulphur per 100 Square Feet pH desired Sandy soil Clay soil8.5 to 6.5 4.5 7.08.0 to 6.5 3.0 4.57.5 to 6.5 1.0 2.0Below 7.0 Do not add sulphur, if pH is below 7.0

Table 2. Pounds of limestone needed to raise your soil's pH

Change in Pounds of limestone per 100 Square FeetpH desired Sandy soil Loamy soil Clay soil4.5 to 6.5 5.0 13.5 19.55.0 to 6.5 4.0 10.5 15.55.5 to 6.5 3.0 8.0 11.06.0 to 6.5 1.5 4.0 5.5Above 6.0 Do not add lime, if pH is above 6.0

As the plants are growing and the vegetables harvested, it is the prime time to evaluate the health and yield of the crops during the past seasons. Previous crops and climate affect the pH and fertility level in the soil.

For almost 20 years, my eight raised vegetable beds totaled 320 square feet. They were different in purpose, size, soil and pH level.The three 4 x 8 feet beds on the east side of the house grew asparagus spears that were harvested when about6 inches tall and up to 1 inch in diameter.

A bed on the south side of the house grew a cabbage plant that was 36 inches wide, and broccoli plants that were6 inches apart with heads up to 9 inches in diameter.

A bed on the east side of the yard-shed had soil that was more acidic. Then it grew a Kennebec potato in a spring crop that weighed 1 pound, and a tomato in a fall crop that weighed 14 ounces.

Source - http://www.theeagle.com/