Getting the Dirt on Soil
What's the difference between dirt and soil? Old-timers were fond of saying "that's
good black dirt." For them, it wasn't soil-it was dirt, with its full meaning of humus,
mineral matter and decaying organic matter. It is the dirt of the old-timers that we call
soil today, full of living things, decaying leaves, plant litter and even dead creatures.
These are the things that change rock particles into that "good black dirt". Think of soil
as a thin, living skin that covers the land, for soil is very much alive. To grow healthy,
productive plants, you need healthy, productive soil. It is this living soil that provides
the food plants need, when they need it and how they need it.
Have you ever planted seeds in soil and watched with amazement as tiny sprouts emerged and
gradually grew into healthy, viable plants? Are you aware that in addition to water, which
is very important, the type of soil that plants grow in and what actually goes on in that
soil will determine how well plants grow?
When the old-timers referred to black dirt, in effect they were referring to the physical
properties of the soil - it's color, texture, structure, drainage and depth. For it is these
features that determine the suitability of soil for planting certain crops and its eventual
productivity.
- Color - surface colors of soil vary from very light to shades of dark to black.
Light colors indicate low organic matter content, while dark can indicate higher
organic matter content.
- Texture - New Hampshire soils, fairly young as soils go, (10,000 years) contain
sand, silt and clay and usually fall into the categories of loam, sandy loam and
clay loam.
- Structure - soil structure relates closely to air and water movement within the soil.
Good soil structure allows for movement of air and water more freely, while poor structure
slows it down. Proper tillage or plowing and the addition of adequate organic matter can
promote good soil structure.
- Drainage - is the amount and rate of water movement in the soil. Simply put, too much
water and plants suffocate; too little water and plants will wither and die - in the end,
the result is the same. Water moves fastest through sandy soils, silt holds more water
and clay holds the most.
- Depth - soils that are deep (30-36 inches or more) and well drained, with desirable structure and texture, are best suited to good plant growth.
The way soils form varies depending upon parent material, topography, climate, vegetation and time, yet all basic soil contains mineral matter, organic matter, water and air. Further, the amount of mineral and organic matter in soils will vary in any given area, depending on the types of crops grown, frequency of tillage and soil drainage.
Soil can be enhanced by the addition of organic matter to produce humus (the end product left from decaying leaves, manure and other living and dead materials). Build the soil with these materials and the earthworms will come, says William Bryant Logan in his thoughtful collection of essays titled " Dirt: The Ecstatic Skin of the Earth ". More than any other creature, worms are the essence of good topsoil. Soil that is rich in organic matter is ingested through one end of the bodies of these amazing creatures and comes out the other end, enriched and well mixed as "castings", Logan explains in one essay about earthworms.
If you are unsure about the suitability of your soil for certain crops or want to know more about its ability to promote healthy plant growth, a soil test can help. Soil tests can be done with a kit from a garden center or by a soils lab. When you collect soil for a test, be sure to take the sample from the root zone (about 6 inches down), collect small amounts from at least 5 spots in the area to be tested, mix them up in a bucket, and then pull a representative sample for testing. Following this procedure will give you the best results.
UNH has a soil testing laboratory which does a basic test (pH, texture, calcium, potassium and phosphorous levels) for $12.00. For $5.00 more you can find out the % of organic matter in your soil. The Analytical Services Lab, located in the Spaulding Life Science Center on the UNH Campus, tests soil samples for researchers, homeowners, farmers, commercial growers, and golf courses.
The Home Grounds and Gardens soil test form includes information on taking a good representative soil sample.
The laboratory staff will analyze your soil sample for pH and nutrient content using the latest instrumental techniques and provide computer generated lime and fertilizer recommendations for specific crop needs. Most samples are analyzed and the results are reported during the next two working days following submission to the lab. If you supply them with an e-mail address, your test results will arrive on the same day they are completed!
For further information contact the Soil Testing Lab at the Analytical Services Lab, Spaulding Life Science Center, 38 College Road, Durham, NH 03824, telephone: 603-862-3210 or at Soil.Testing@unh.edu or at the UNH Cooperative Extension web site . The lab is open M-Th, 8:00-12:00 and 1:00-3:00 except on recognized UNH holidays.
Soil and plants play a very vital role in the well-being and survival of both humans and animals. Soil helps protect plant roots from the sun's heat and filters pollution from rain and water runoff. And soil is what plants need to grow and be supported in as they grow. It is used for food, fabric dyes, medicines, beauty products and building materials, to name but a few uses.
For more information call the UNH Cooperative Extension's Family, Home & Garden Education Ce nter's Info-Line toll free at 1-877-398-4769 for "Practical Solutions to Everyday Questions." Trained volunteers are available to answer your questions Monday through Friday from 9:00am to 2:00pm.
Nancy P. Adams, Master Gardener, UNHCE, Hillsborough County