Soil Fertility

Thom Marti, of Broad Valley Orchard, dropped in our soil fertility workshop to talk a little about what healthy soil is composed of and how you can improve your soil to be able to grow abundantly.

Soil fertility, the capacity of a soil to provide crops with essential plant nutrients, posesses the following properties:

  • Rich in nutrients such as potassium, nitrogen, phosphorus, and carbon
  • Sufficient trace minerals are present, such as iron, copper, manganese, magnesium, and zinc
  • Organic matter is present, retaining moisture and improving structure
  • Soil pH is between 6-7 for most plants
  • Soil life, such as microorganisms and some organisms such as worms, is present within the soil
  • In some cases topsoil is present
  • Soil is aerated, moist, and loose enough for roots to move freely

When Painted Turtle Farm was started in the 2005-6 school year, the plot was previously uncultivated and primarily made up of rocky clay-type soil. While most trees and shrubs grow well such a  clay rich soil, the roots of the most of annuals, perennials, and vegetables are often to weak to develop fully and move in the packed soil. In addition, soil rich in clay has the tendency to drain and change temperatures slowly, to compact easily, to heave in the winter and to be alkaline.  Over the years, additions such as mushroom compost, sand, peat moss, and other organic matter and composts from local farmers, as well as from our own piles, have been been added to the field and the beds to enrich the soil.

According to the Soil Survey of Adams County:

“Adams County is rather cold in the winter and hot in summer. Winter precipitation frequently occurs on most soils, results in a good accumulation of soil moisture by spring, and minimizes drought in summer. Normal annual precipitation is adequate for all crops that are adapted to the temperature and length of growing season in the area.”

Thom showed us some examples of the red earth that is naturally present in this particular area of Gettysburg, and how it has changed over the past eight years through cultivation and the addition of organic matter, etc. Thom also brought along a sample of how different the soil is in Biglerville where the Marti farm is located, and a sample of some soil from a garden bed. The soil that had been worked with, of which the health had been improved over many years, was darker, sweeter in smell, and had a medium loamy texture.

As we work in the garden, it’s reassuring that we can slowly see the fruit of our labors in the changing texture, color, organic life, and richness of our soil.

Students work on spreading mushroom compost around the back field in early spring.


The soil after the compost was tilled in earlier this spring.


The soil a couple weeks ago, right after seedlings were transplanted.



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