Tuesday, June 20, 2017

How Can You Make your Vegetable Garden More Sustainable?


By June most of our seeds have been planted and are up and growing.  And yet there may still be bare areas in our garden.  Perhaps we are leaving room for tomatoes or peppers or squashes to grow.  Often we think that leaving room means leaving bare soil, but naked earth is exactly what we do not want. 


Bare earth is “dirt,” in the words of soil microbiologist Dr. Elaine Ingham1.  What we want in our garden is not dirt, but living soil.  She and other scientists tell us that most of the life in our garden is beneath the surface and needs plant roots in order to thrive.  We need to feed those microorganisms around our plants’ roots by making sure there is little or no bare areas in our gardens.

We grew up learning about the types of soil (sand, silt, loam and the clay we have around here) in which we grow our plants and the chemicals in the earth that support plant growth, particularly N-P-K (nitrogen, phosphorus, and potassium that we use to feed our plants).  We learned about composting to improve our soil texture and chemistry, but until recently most of us had not heard much about the biology of the soil, all the little organisms eating and being eaten, pooping and reproducing in our dirt so that it becomes living soil.
 
These little guys include -- but are not limited to -- bacteria, fungi, protozoa, nematodes, and micro-arthropods as well as earthworms.  We know that worms are signs of good soil, but until recently scientists did not understand that they were part of a complex soil food network that involves thousands of kinds of organisms.  Worms are the part most of us can see without a microscope, and they and the rest of the soil community are essential to the life of our plants.  Most of these soil organisms live near the roots of our plants.  As they eat, grow, and move through the soil, they make it possible to have cleaner water, cleaner air, and healthier plants.
They decompose manure, dead plant material, and even pesticides, preventing them from entering water and becoming pollutants. They sequester nitrogen and other nutrients that might otherwise enter groundwater, and they fix nitrogen from the atmosphere, making it and other nutrients available to our plants.”2 Many of these little guys enhance soil texture, reducing runoff, and they also prey on crop pests.  Because they thrive around the roots of our plants, where there is bare ground, they die off.

So, what do we do with bare soil that is waiting for our tomatoes, peppers, squashes and pumpkins to spread over it?

Several things come to mind:

We can plant quick-growing plant seeds like radishes that will cover the ground until our crops fill in the space, preventing weed seeds from finding a home and giving food to the millions of micro-organisms in our soil,   

or plant flower seeds that attract pollinators to our gardens. Territorial Seed Company informs us that a female pumpkin flower needs to be visited 8-10 times by a pollinator for adequate pollination.  They suggest planting bee-attracting flowers such as borage or cosmos next to pumpkins to help generate higher yields3.

Interplanting in our garden beds can increase our yields and keep our underground workers happy as well.  Look at this idea:  baby spinach growing between rows of garlic.  The spinach leaves will be harvested before the spinach plants bolt and the garlic is ready to pull.  Lettuce is another ideal crop because the thin garlic leaves partially shade the early leaf crops as they, in turn, keep weeds from spouting in the garlic.

Here is the same idea in reverse:  onion sets growing between rows of broccoli and kale.  Plant tall leaf-growing plants in between wide leaf-growing plants and wide leaf-growing plant in between rows of tall leaf-growing plants. 




Also consider growing crops in blocks rather than rows.  Here are blocks of Swiss chard, beets, and lettuce separated by rows of beans.  The beans were planted between the blocks when seeds were not sown evenly.


All these growing ideas are like green mulches – keeping the weeds out and the soil moist on hot summer days -- and also helping the little organisms build a living soil.

We can also help the food web within our soil overwinter by planting cover crops.  And that’s also why we encourage all gardeners not to till their gardens in the spring because tilling interrupts the food web that is being built up in our soil.  Remember that building a living soil makes for healthy, delicious, sustainable plants in our gardens.

References
1Elaine Ingham, www.soilfoodweb.com


3Territorial Seed Company seed packet for Small Sugar Pumpkins.

For Additional Information on Soil Organisms

The Soil will save us, Kristin Ohlson, © 2014, Rodale Publishing.




Many thanks to Karen from the Corvallis Sustainability Coalition's Food Action Team, Edible Garden Group (FAT EGG) for this very informative and beautiful post!


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