The No Till No Dig Way: Revisiting Soil Tilth and The No Till Garden
I wrote that article almost exactly two years ago. I better understand now that not only do soil organisms improve soil, but plants as well do a great deal to improve soil. In their relationship with soil organisms plants leak exudates mostly in the form of carbohydrates to attract organisms to their roots. Plants accumulate these carbohydrates through photosynthesis, and can afford to leak out as much as 25 percent of the nutrients they manufacture through photosynthesis as root exudates. In leaking exudates and attracting organisms to their root zone or rhizosphere plants are initiating a relationship with organisms like fungal mycorrhizae. Mycorrhizae in exchange for plant exudates attach themselves to plants roots and make hollow strands or tubes called fungal hyphae (hi fee). These mycorrhizael hyphae can grow 20 meters, or 60 feet a day. They serve to increase the reach of the plant carrying moisture and minerals and other organisms like phosphorus solubilizing bacteria to the plant’s roots. Phosphorus is often bound up in soil and unavailable to plants in its bound up form. In our calcareous soil phosphorus binds with calcium. Certain types of bacteria and some fungi are capable of solubilizing that phosphorus, making it available to plants. Mycorrhizae bring these organisms into the rhizosphere where they then make locally bound up phosphorus soluble for the plants.
In addition to feeding soil organisms with their exudates, plants send their roots into the spaces between soil aggregates, choosing the path of least resistance they further open spaces in the soil allowing air and water to flow along the roots’ paths more deeply into the soil while helping to hold the soil from erosion. The farther air and water go into the soil the farther soil organisms and invertebrates can go, and with them organic matter, making nutrient rich lively soil deeper and deeper. This is the answer to my question about how organic matter piled onto the surface of soil helps fix the soil below. This is the basis for my newest practice of laying a double hand full of compost on the surface of unimproved soil, placing seeds into the compost, covering with straw or fine leaf mulch and watering. It is a way of using new plants and organism rich compost to spread soil health. The seedlings thrive in the compost and then drive their roots down into the unimproved soil bringing the compost organisms with them. The mulch above gives protection from direct sun, and a food source for the organisms in the compost until the plant is ready to begin the nutrient exchanges.
As for the roots of my tree; the tree is a Weeping Yaupon Tree. I have not dug roots out for 2 years now. I have no idea what is going on below the surface, but on the surface I am always adding layers of mulch, and just below the mulch I have lumpy black worm castings, and the plants I grow there do just fine, so I quit worrying about what the tree is doing below the surface.
My garden grows beautifully. All I do is feed the soil with lots of organic wastes. I don’t dig, I don’t worry, I don’t fertilize plants and I don’t spray plants. All in all I would say that growing the No Till No Dig Way is an easier, more successful way to nurture a food garden.