PLEASE DON'T CALL IT DIRT!
by Vern Grubinger
Vegetable and Berry Specialist
University of Vermont Extension

Soil is at root of good crop production, but all too often, as the saying goes,  it “can’t get no respect.” As vegetable growers, we push it around, drive all over it, leave it exposed to the elements, and feed it junk food.  In other words, we treat it like dirt.

Good soil deserves better. Afer all, it’s miraculous stuff--tens of thousands of years old, chock full of nutritious minerals, able to retain as well as drain water, and home to millions of micro-organisms in every teaspoonful.

Being a little nicer to this agricultural super-hero we call soil is a smart move that will pay off in subsequent years, and for future generations. The basic approach to soil stewardship is simple enough: avoid harmful practices that cause erosion and compaction, and engage in good practices that add organic matter and improve soil structure. Here’s a short summary of how to maintain, and even improve, your soil’s health.

Don’t give away the store. While it takes millennia to make topsoil, it only takes moments to lose it. Blowing wind and flowing rainfall are the agents of erosion. To protect against them, avoid nudity. Cover up the soil every chance you get. Sow the alleyways to a cover, and put on a cover crop whenever harvests are complete. In fields that finish up while it’s still summer, buckwheat is good for a quick  month or two of ground cover before fall. After fall harvests, sow oats, rye or other small grains ASAP so your fields will be protected over winter.

Take a break. By working every field, every year, you may make some more money now, but it will cost you later as soil quality deteriorates. A good vegetable crop rotation periodically takes land out of cash crop production, ‘resting’ it with a soil improving crop. For multi-year rests, most any kind of perennial hay crop will do. For a single year off, a sequence of cold-weather and warm weather cover crops, like field pea / buckwheat / winter rye can be used. Rigorous crop rotation helps reduce disease, insect, and weed pressure as well.

Breathe deeply. If you squeeze the air out of soil by performing tillage when it’s too wet the resulting compaction will reduce root growth and prevent drainage, lowering crop yields for years to come. Frequent use of heavy equipment also compacts soil. Using permanent roadways in your fields can help avoid compaction from vehicle traffic. If you’ve already got compaction, subsoiling may help, as can certain cover crops. Research in upstate New York has shown that Sudangrass as a summer cover crop or perennial ryegrass as a fall / winter cover crop are good choices for remediation of compacted soil. The combined use of subsoiling and cover crops provided additive benefits to the soil.

Promote physical fitness. Soil structure is the physical condition of the soil. It’s so important that we’ve got lots of ways to say it. A soil with good structure has tilth, it’s friable, crumbly, even mellow.  A soil in good physical condition is porous and easy to work. It has  plenty of aggregates, which are tiny clumps of stuck-together soil minerals and organic matter. Avoiding erosion and compaction can help protect soil structure, but adding organic matter on a consistent basis is the key to maintaining or improving the physical condition of your soil.

Eat a balanced diet. Growers pay a lot of attention to the mineral nutrients in soil that crops need, like N-P-K. When they’re in short supply, fertilizer is applied. But carbon should also be added to the soil. Carbon isn’t considered a fertilizer nutrient since crops get it through photosynthesis. However, the soil is full of microbes that can’t photosynthesize, and they’re hungry for carbon. These microbes are key to improving soil structure because they’re messy eaters, and they leave a lot of slimy by-products around which help bind soil particles together. So, while they eventually consume most of the carbon that’s applied to the soil, along the way they help make soil aggregates. Compost, cover crops, and green manure crops are all good carbon dishes to serve your microbial buddies. Just don’t ask them over to dinner.

Keep an eye out for trouble. Your friendly Land Grant University has been subsidizing the cost of soil tests and providing localized fertilizer recommendations for many decades. Take advantage of this opportunity to monitor soil fertility. In addition to pH and major nutrients, get some extra things tested like trace elements and soil organic matter. Test every field on your farm, at least every 3 years. Growing crops without soil tests is like flying a plane without radar. Sure, you can do it, but if you don’t know where you’re going, you’ll probably get there.

For more information on this topic order the book ‘Building Soils for Better Crops’ by sending a check  for $20 plus $4 shipping to: NE-SARE, Hills Building, UVM, Burlington VT 05405-0082 or visit www.uvm.edu/~nesare/. To order using a credit card, please call 802-656-0484.

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