We’ve mentioned so frequently that our native soils are not so great. Our “topsoil” is what most other gardeners or farmers would consider poor mineral subsoil. The 100 or so local soil tests I’ve seen or had done over the decades have all produced remarkably similar results: “plentiful phosphorous and potassium, ample micronutrients (glacial rock dust), .000001% nitrogen, .000001% organic matter, a little lacking in calcium and sulfur.”  When you dig a hole and loosen the native earth to allow moisture infiltration, oxygen and to improve drainage, those improvements last, maybe, a season before that bit of earth returns to the nearly concrete state it was in before you dug. In less arid environments and at lower elevations, organic materials fall from the vegetation and are naturally composted back into the soil to create a rich, living top soil. In the high Sierra, our natural decomposition (composting) only occurs in winter, under the snow, almost entirely by fungi. Fire was once the primary means of nutrients cycling back into the soil here.

When we add organic fertilizers and organic composted soil amendments as we plant, our rotten mineral subsoil / topsoil becomes not-so-bad. Mature, fully-composted organic materials will have a healthy and moderate carbon to nitrogen ratio (C:N), lots of humic acids, billions of beneficial microorganisms, and some nutrients. Mature composts, mixed into the soil create and maintain air-spaces to prevent compaction, hold water, hold nutrients (cation exchange), allow for gas exchange (oxygen is AS important to roots as water is), and improve moisture infiltration and drainage. You can see why ~90% of all roots are in the top ~12-18″ of soil. Organic fertilizers also add lacking organic matter to the soil, they inoculate the soil with beneficial microorganisms and provide those same creatures long-lasting sources of nutrients that they, in turn, break-down and give to the plant roots. Most plants actually exude sugars and nutrients into the soil around their roots in order to encourage the biology in their rhizosphere… they evolved with each other.

Organic material added to the soil does not remain for very long and the nutrients we add are rapidly used by plants. This spring I’ve spoken to so many people who fertilized once and thought that was good enough. Obviously, plants can survive without additional nutrients, wild plants do it all the time. It is important to remember however, that in the wild, roughly one in a million seeds ever germinate and grow because that seed found JUST the right location, made just the right microbial associations, had just the right climatic conditions and just the right moisture. There are millions of plants in the wild but they are the results of billions and billions of attempts. Most of us would like better odds than those in our home gardens.

Mulching over the soils surrounding your garden plants with several inches of ground wood prevents weeds, moisture loss and soil damage while providing a lasting source of organic material to decay and insinuate into the topsoil. Mulching is ridiculously beneficial. It may be the simplest and cheapest garden activity that provides the most dramatic benefit. I believe that 3-4″ of mulch will reduce watering by about half while roughly doubling growth. Consider that in our dry, high elevation landscapes with fine, silty soils, an un-mulched area ten feet from your plants with the wind blowing and the sun shining, will wick away water from where you are providing it so mulch broadly. Our dump has “double-grind” wood chips for a little over $20/ cubic yard, and both the Town of Truckee and Tahoe Donner usually have huge piles of slightly coarser material available as well. Pine needles allow too much sun and wind to penetrate them to provide very effective soil protection, not to mention that they are more readily flammable for the same reason. As fungi grow through wood mulch, they maintain a much higher moisture content.

Providing regular additional organic fertilizers helps ensure that there are bacterial and fungi infiltrating the mulch layer to compost it at the soil interface and that there is are ample and available nutrients to keep your garden plants actively growing and thriving, as opposed to just barely “surviving”.

We are fans of using aged / composted (2 yrs-ish) horse manure. Most folks with horses are delighted to provide it for you for free. We also like and use bagged mature composts from a small handful of companies (Bumper Crop, Kelloggs and G&B).  We’ll add chicken manure or a farmyard blend of manures to a veggie or flower bed. I love worm castings (worm manure) for the biology and humus it contains. Biosol is probably our favorite all-purpose fertilizer for everything from bulbs, seeding, vegetables and planting, to established lawns and trees. I have been known to use G&B Lawn Fertilizer on my entire yard and garden as well… I reckon that since the main nutrient we’re lacking is nitrogen (N), a fertilizer that’s 8-1-1 (N-P-K) seems just about right… a little on the lawn, a little on the trees, a little on the ground covers a little on the leafy greens, etc…  We do frequently add calcium to plants that may be native to limestone soils or simply use more than average: bluegrass, clover, delphinium, dianthus, lilac and peony (among a few others).

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