Sunny Slope Orchard

Sunny Slope Orchard
In the coast range foothills overlooking the Sacramento Valley

Wednesday, July 20, 2011

Our dry farmed/No-till soil management

Our last post began a discussion of how we manage soil moisture and fertility. To summarize, our orchard is mostly dependent upon winter rainfall rather than summer irrigation since water is very scarce in these hills. This area was historically "dry farmed." And according to the gospel of dry farming, that meant cultivating the soil as soon as it was dry enough to work in the spring. The object was to plow under all winter weeds so most of the winter/spring rainfall was preserved for the orchards instead of going into weed growth. To "seal in" the moisture, the ground was cultivated repeatedly as weeds re-emerged, leaving a fine "dust mulch." Unfortunately the result of bare, finely cultivated soil is erosion of top soil, death of soil building organisms, and continual loss of fertility.

So our challenge with dry farming is how to save the maximum rainfall moisture for our main crop (orchard trees), while also preserving and improving soil fertility. Our solution has been to simply mimic nature's soil building process, with some enhancements. Some years back I began planting a cover crop in the fall, one that adds maximum organic matter and nutrients to the soil, rather than just letting native weeds grow. I also stopped tilling every spring, opting instead to just mow near the end of the rainy season. The result has been a real slowdown in erosion and a big increase in fertility, all with no apparent sacrifice in soil moisture.

Now instead of a finely powdered soil devoid of life, we have the rich porous soil pictured here, protected from sun and wind by cover crop residue, full of decaying roots that microbes turn into fertilizer, and permeated with earthworm holes that allow air and water to enter. Instead of winter rain runoff looking like chocolate milk, very little rain runs off since it is slowed by dense cover crop and easily soaks into the sponge-like soil. In short, our soil is now capturing and holding more moisture and building more fertility. Our annual soil test lab results show high to very high nutrient levels and steadily increasing organic matter content, all without any inputs other than compost and natural mineral amendments.

Because soil biological activity is nature's fertilizer factory and all soil life requires moisture, we use what meager well water we have to do some minimal drip irrigation through the dry summer season. Call it "dry farming plus." By putting a mound of compost under each drip irrigation emitter, we create small zones where earthworms and microbes flourish. These function as feeding stations for the trees, providing a small but steady supply of nutrients and trace minerals.

A mass of fine feeder roots forms under each mound, absorbing nutrients along with a bit of water. The amount of water is only a tiny fraction of what irrigated orchards get, but our big juicy fruit, deep green leaves, and rampant tree growth speak for themselves. Clearly the trees are getting plenty of what they need. Because they have never been irrigated, the root systems have grown deep to survive the dry summers. And while they will look a bit stressed during low rainfall years, the high soil nutrition gives them the strength to cope until the fall rains start again.

What really drives our passion for the orchard is fruit flavor. We are gratified to hear customers frequently comment, "that was the best I ever tasted," or "I haven't tasted fruit like that since I worked on my grandparents' farm." Producing such exceptional fruit with minimal water and without synthetic chemicals just feels right.


  1. Wonderful. Intermittent draught is a problem we have in Northland New Zealand. We could not plant fruit trees until we knew of a way to succeed with it. Thank you for your technical information.

    I too have felt that fruit does not taste as good as in the past, so congratulations.

  2. To Anonymous: You might try looking around your area at abandoned/neglected properties to see which types of fruit trees survive without regular water. Be aware that citrus and figs require more water than stone fruits.

  3. Hi Bill - Thanks for this great post!

    I work in a 3.3 acre public orchard in San Jose. We've had lots of irrigation issues so I'm intrigued by dry farming.

    What's the annual avg rainfall on your property?

  4. Thanks, our rainfall averages 36". That's much higher than the surrounding valley areas. Our elevation and proximity to a nearby higher mountain range cause lots more rain to drop here. However I'm not sure the extra rain makes too much difference to the trees since being on a slope, heavy rains run off once the ground is saturated. Also our soil is fairly sandy so its moisture holding capacity is less than a clay loam.