It is finally “that” time of year: in a bit more than a month we can all look forward to planting our gardens for the coming season. How do you prep your garden / soil for the growing season? In the Spring edition of our 2009 newsletter our UWEX advisor, Kevin Jarek, shared with the membership the importance of no-till gardening. Many people (especially those with fancy cultivators) won’t subscribe to this style of gardening, but listen to what Kevin has to say and decide for yourself:
For decades gardeners have traditionally turned over the top layer of soil in an effort to get rid of weeds and make it easier to apply fertilizers and plant crops. Working the soil was often considered one of the most back-breaking tasks associated with gardening, especially true for those with clay-based soils. This “tillage” was often a means to speed up the decomposition of crop residue, weeds, and any other organic matter in preparation for the next season’s planting.
When converting from traditional or conventional tillage, it is probably easier to think about no-till as a process of construction rather than disruption. Any gardener would tell you they would love to have a soil which is dark, naturally crumbly, and they could effortlessly put their fingers through. The Golden Rule with no-till gardening is to avoid inverting the soil and tread lightly or not at all on your planting area. In no-till gardening, once the bed is established, the surface is never disturbed. A healthy soil structure is the result of a complex, symbiotic relationship that exists between the soil surface and all of the underlying micro- organisms. When we till or dig into this existing environment, we end up disrupting these naturally occurring processes. While tilling can have a positive effect on plant growth by creating a higher soil temperature, more aerated environment, and an area that initially results in accelerated plant growth – the consequences over the long term may outweigh the benefits.
Excessive conventional tillage to a soil over time could lead to a number of problems including erosion, compaction, and the loss of beneficial soil microorganisms. Constant tillage breaks down soil structure, making it more susceptible to wind and water erosion. Tillage at the same depth year after year will result in subsoil compaction referred to as a “hardpan” or “plowplan”. University of Wisconsin research has shown that this form of compaction can remain in place for a decade or more if nothing is done to correct it. This particular problem not only limits root depth because of restricted penetration, but the compaction also results in less air exchange from the rooting zone, limiting root health. Ecological theory states that a complex system is more stable than a less complex system. In this case, that means that there is less likelihood of severe or devastating pest outbreaks because of the numerous checks and balances that exist in a complex soil environment as opposed to a simple one. The constant presence of more slowly decaying organic matter has the largest positive impact on the population of naturally occurring biological control agents. Some of the soil microorganisms that increase the complexity include beneficial fungi that would naturally attack and control undesirable invaders like plant-eating nematodes. Some studies suggest that no -till gardens contain 50% to 500% more beneficial predators, regardless of the amount of pests present. The loss of bacteria, fungi, and earthworms also disrupts the plant nutrient cycle. A healthy, organic soil should contain 7-12 earthworms per square foot. The absence of these natural recyclers often results in more supplemental fertilizers being applied to maintain production. Another downside to conventional tillage is that there are approximately 5,000 weed seeds in a cubic foot of soil and this activity results in buried, dormant seed making its way to the surface placing it in an environment where it can now germinate successfully add- ing to a never ending problem. Conventional tillage also releases C02 into the atmosphere, whereas a rich, undisturbed organic layer would hold this carbon in place in undisturbed plant remains.
Amendments to the soil are still necessary when utilizing no-till. However, instead of working these items into the soil through accelerated means, – compost, peat, lime, manure, and other items are “top-dressed”. Soil microorganism activity and watering will eventually pull these materials through the topsoil and into the subsoil. The addition of this top-dress results in the need for less weeding. When materials are added in layers, this makes it easy for newly planted seedlings roots to work their way through the spongy underlying soil surface. In essence, this method mimics the process by which soil is formed under natural conditions.
Submitted by Kevin Jarek, Outagamie County UWEX Crop, Soils and Horticultural Agent
Posted by Vicki