SOIL PREPARATION

Soil condition is important to maintaining a healthy organic garden.  The soil should be free of all vegetation, and that includes the current years weed crop, as well as the remains of last year’s vegetable crop.  The soil should have the correct pH and be light, sweet, and full of humus so that there is proper drainage and plenty of air available to the roots.  Also, the soil should be free of  insects, weeds, and remnants of disease.

SOIL TESTING.  

The only way to be sure of the condition of your soil is by having a laboratory run a soil test.  The test is easy to do and often can be done free of charge.  In the U.S. exact information on how to test your soil can be obtained from the U.S. Department of Agriculture (USDA) or the Cooperative Extension Service with offices in most U.S. counties.

The soil test is essential in maintaining a productive organic garden.  It provides the information needed to adjust the soil elements such as pH and mineral content.

SOIL pH.  The pH scale divides the range of alkaline and acid into 14 points.  Halfway is 7, and that is neutral.  Below 7 is acid and above 7 is alkaline.  Most plants do best when the pH is between 6.2 and 6.8 or slightly on the acid side.

THE pH GROW ZONE

ADJUSTING ACID SOIL.  Sandy soils are naturally acid.  Plants grown in soil that is too acid are stunted, small, poor producers, and susceptible to insects and disease.

 TREATMENTS FOR CORRECTING ACID SOIL

• LIMESTONE: 5 pounds of ground limestone per 100 square feet will raise the pH about 1 point.
• COMPOST: Compost is a good way to adjust pH because it works on both acid and alkaline soils.
• WOOD ASH: Wood ash raises the pH and provides potash, which is an essential plant nutrient.

ADJUSTING ALKALINE SOIL.  Clay soils are typically alkaline.  Plants grown in soil that is too alkaline become stunted, pale, and unhealthy.

 TREATMENTS FOR CORRECTING ALKALINE SOIL

• COMPOST: Compost is a good way to adjust pH because it works on both acid and alkaline soil. Work a generous amount of compost into the soil to a depth of 10-12 inches.
• GREEN MANURE: Plow under a green crop (called green manure) such a wheat or rye.  Green manure enriches the soil and helps eliminate soil-borne diseases.  Plant crops after the decay is complete, which is about 6 weeks during warm weather.
• PEAT MOSS: Peat Moss is acid and therefore can be used to lower the pH.  Use 50 pounds per 1000 square feet to lower the soil pH by 1 point.

COMPOST PREPARATION.

Compost is decomposed organic material.  Any organic material can be used, including kitchen scraps, lawn clippings, leaves, hay, weeds, and manure.  Meat scraps and manure from carnivores such as dogs and cats should not be added to the compost pile. 

Although there is a great variety of compost containers and supplies available, compost is best when piled out in the open with no additives, because it will breakdown more slowly and end up with a stronger friendly flora which ends up making healthier soil.  Water when necessary to keep the pile moist.  Turn the compost completely over 3 or 4 times during the decomposition period.  Compost is finished when it turns a rich, dark color and has a sweet smell.  Composting can take from 6 weeks to 8 months, depending on additives and manure content.  The more manure and green vegetation in the pile the faster the decomposition.  Compost can be worked into the soil or used as mulch.

SOIL PASTEURIZATION.  Soil pasteurization can be accomplished by using a procedure know as Soil Solarization.  Solarization rids the soil of garden pests such as bacteria, fungi, insects, and weeds.  After solarization the soil is completely sterile.  Solarization must be done during several weeks of warm weather.

 PROCEDURE FOR SOLARIZING THE SOIL

• PREPARE SOIL: Remove all debris and rake the plot smooth.
• SOAK SOIL: Soak the soil with water for several hours.
• COVER WITH PLASTIC: Cover with a clear plastic sheet—do not use black plastic.  Overlap edges by 1-2 feet.  Cover edges with soil to seal in moisture.
• PASTEURIZE THE SOIL: Leave plot covered for 6 weeks.  Sunlight shines through the clear plastic and heats the soil.  After pasteurization the soil is ready for planting preparation.

GARDEN SANITATION. 

At the end of the growing season, old plants should be cleared away and either composted or burned.  Plants left in the garden after the growing season is over become a harbor for insects and disease.  Diseased plants should be burned or composted to prevent re-infection of the soil with the same disease.