Soil Tilth And The No Till Garden
I am having a revolution in the garden of my mind. That garden happens long before I tie on a bandana, don gloves hat and clippers and walk out the door. As I prepare several of my garden sections for the South Florida Fall planting I am for the first time planning not to dig or turn my garden beds before planting. The reason why is that I am getting a better understanding of the nature of soil. It is so much more than a medium for plants. Soil needs to be recognized as a whole ecosystem rather than just a medium, because as an ecosystem it has a symbiotic relationship with plants which is of greater benefit to them and to you as a grower if left whole and unturned.
The first gardens were probably “no till” gardens. When we started doing farming we began plowing ahead of planting. The model for the post agricultural gardener (that’s us) was a miniature version of the farm. We tilled or turned our soil too. Now many farmers are exploring the benefits of no till farming. Here is why we should too.
In earlier posts on this site you read about compost Invertebrates Of The Compost Pile like earthworms, and compost Microbial Life Of A Compost Pile like bacteria and fungi. Many of those are also residents of healthy garden soil. Imagine your soil as a giant woven living sweater. It has filaments of fungi called hyphae (say “highfee”). It has worms’ tunnels lined with castings, and a huge community of bacteria. (the good bacteria.) 😀
Fungal hyphae filaments weave throughout the soil. They produce humic compounds (humic compounds are not only good for soil they may assist plants with respiration) and organic “glues” that bind soil into aggregates. Aggregates are clumps of various sizes they are a sign of soil health or tilth. They help soil resist erosion and compaction which improves soil porosity. Soil porosity and soil structure positively influence the growth of plants by helping to keep soil open to better oxygenate and moisturize. A type of fungi called mycorrhizae (my-cor-ry´-zee) colonize in and on plant roots and assist plants in pulling more moisture and nutrients from soil. Plants with colonies of mychorrhizae in their roots can acquire nutrients from farther than their roots would otherwise reach. Mychorrhizae also make it more difficult for root knot, or plant nematodes to invade plants roots. Mycorrhizae also produce hormones and antibiotics that enhance root growth and provide disease suppression. The mychorrhizae are able to feed on nutrients and carbohydrates from plants’ roots. Their relationship with plants is a symbiosis. Some invertebrates in soil will eat soil fungi if it is present, or they eat the tender roots of your vegetable plants if fungi is not present.
Bacteria in the soil work in two ways to help create soil aggregates. They produce polysaccharides. Bacteria polysaccharides are more stable than plant polysaccharides and resist decomposition long enough to help bind soil into aggregates. Bacteria also develop a small electrostatic charge which may also help soil to aggregate in the case of clayey soil. I don’t know if the electrostatic charge helps aggregate my naturally sandy soil.
Worms eating through organic wastes in the soil make deep complex tunnel systems through soil, constantly leaving their castings in the tunnels and above. Worm castings are famously perfect fertilizer for plants. The tunnels contribute to the structure of soil and help to bring oxygen, and moisture to greater depths, the castings provide nutrients for the plants, bacteria, and the fungi.
If I push my shovel into the soil and dump it over I have just collapsed its woven structure. Now my soil is going to compact more easily making it more difficult for my plants to push their roots through it. If it rains hard my turned soil is more likely to wash away. In flipping the soil I have unearthed long buried weed seeds which will now come to life. It will be more difficult for oxygen and moisture to penetrate my fallen soil, and fungi, worms and bacteria must begin again to weave their magic into my broken soil, but it will not happen quickly enough to be of great benefit for my plants this season, and many worms disturbed by my soil disruption will perish.
Yet in previous seasons of gardens I planted into tilled soil that brought forth great harvests. This no till garden will have to prove itself to me, and I do believe it will. The idea of soil as an ecosystem appeals to me. It easily fits into my view of the natural world. Doesn’t it make sense to you too?
So here are the questions that go through my mind as I am imagining how my garden will work if I don’t turn the soil. I wonder how nutrients will get down lower than surface level if I only lay compost, manure, and mulch on the top. I wonder if the tree roots that get into my garden will use all the nutrients before my vegetables can if I don’t dig down and break them before each season.
I read that nutrients laid upon the surface of the “no till garden” soil will become the new top layer of the soil. My preparations for this garden so far have involved laying down layers of hay manure straw and compost I just won’t turn it all in this time. Soil with proper tilth, (health), will have aggregates, and pores and tunnels. Nutrients will easily leak into it when it rains, and worms will continue to tunnel deeply leaving castings wherever they go. My plants will make their first tender roots in fluffy compost over manure over straw. If everything goes as planned that should be easy for them. As they continue down they will find the worm tunnels and the castings, yum yum. ahahahahaha. I think my plants will like this.
I haven’t found an answer that covers tree roots. I am going to have to play that one by ear. I will for sure be writing about how this no till garden goes this season. Please stay tuned.
Whether or not this no till style of gardening is your choice this year it is worth rolling it around in the garden of your mind. Here in the soil exists yet another micro-ecosystem. It is possible that we have been bending our backs to break our soil to its detriment and to the detriment of our plants.
Happy Planting South Florida 😀
Adina, I am doing the same as you. We started our garden in virgin soil here in the high (6300 ft. elevation) desert plains in Colorado about three years ago. Our garden is huge and it was not all planted until last year. Our soil is light brown in color and all clay. It bothers me to leave this clay as is and not till organic material into it. I don’t see how any roots could even push their way through it, though I see evidence that they do.
You say, ” The idea of soil as an ecosystem appeals to me. It easily fits into my view of the natural world.” Me too, it makes total sense to me.
Thanks for your comment Sally. I think you have realized that if you offer lots of organic matter to the soil surface the invertebrates that come to consume it will also work it into your clay for you.
How about using green manures on clay soil? Depending on your climate of course – caliente mustard is reputed to be capable of rooting into hard clay pan, breaking it up. I guess you would sow it into a top layer of compost to get it established.
Yes absolutely. I read that Matsanobu Fukuoka used daikon radishes to work his clay soil. Each radish (daikons can be huge) breaks into the soil to a great depth, and of a decent breadth as well, and if not harvested it leaves a mass of organic material there where clay once was. I have found that just a two hands full pile of compost is enough to start a seed over bad soil. Once the seed is planted into the compost on top of the soil I cover the compost with straw or leaf mulch to protect the compost and its organisms. In addition to mustards and daikon radishes, I am sure there are many other deep rooted plants that help to work clayey soils.
Thanks for your comment V.