The latest in soil news include a new Soil Health Landscape Tool, the effect of mycorrhizae on tree ecology and the positive effect of soil microbes on plant’s defence system against pathogens.
This year on #groundchat I’m going to keep up with soil news, studies, and updates that impact our gardening world. Since I’d not covered updates on soil for a while, there is a significant amount of information since the last #groundchat soil news blog.
The first exciting update was Soil Health Institute’s release of a Soil Health Landscape Tool. This free tool has more than 1,000 references. And it’s available to the public. The science papers include studies in erosion, nutrient depletion, and compaction. Great tool to have on hand to check on the latest scientific advancements in soil management.
Our understanding of soil and plant interaction has skyrocketed in the last decade. There has been a corresponding rise in popular science articles. The New Scientist magazine examines the latest studies on plant/soil interactions and how it affects ecological diversity.
It’s well established that plants and soil biota can regulate one another. What’s new is the complexity of the interaction. The tree/fungal association, for example, is more than the harnessing and exchange of nutrients. We have known for a while that tree species associate with mycorrhizal fungi. New evidence show that the type of mycorrhizal association affects tree distribution.
First, studies show that tree species colonized by ectomycorrhizal fungi were better protected from pathogens than arbuscular fungi. This extra protection by ectomycorrhizal fungi isn’t surprising. Ectomycorrhizal fungi form a thick sheet around root tips whereas arbuscular mycorrhizal fungi do not. What was startling was finding that ectomycorrhizal tree seedlings prefer growing close to parent trees, but arbuscular mycorrhizal tree seedlings could not. Arbuscular mycorrhizal tree seedlings could only establish in different soils, away from their parents.
How does this affect our gardening practices?
Find out what mycorrhiza affects your trees. If the tree has an arbuscular mycorrhizal fungal association, plant seedling of that tree species far from the mature tree. Any tree species with an ectomycorrhizal fungal association can have their tree seedling planted close to the adult tree.
As fungal networks provide so many services to trees, it makes sense not to disturb the soil around trees. Cultivation would damage to the fungal network. It’s an old gardening practice, but now we’re starting to understand why it’s so critical.
Soil microbes critical for plant’s defense system
New York Times June 2016 article, “Scientists Hope to Cultivate an Immune System for Crops,” analyzes the complex role soil organisms play in protecting plants from disease. It turns out that soil microbes —fungi, bacteria and other small organisms — acts as plants’ immune system in the ground. A microbe-rich soil turns out to be the best defense against pathogens.
This little tidbit of information confirms what gardeners have known all along. Compost, which has plenty of microorganisms, is good for the soil and plants. Rather than just improving the soil by increasing organic matter, we now know the extra boost of microorganisms found in compost also improves plants’ defenses against soil pathogens.
Any practice that diminishes soil microbes —tilling and large amounts of chemical fertilizer—affects the plant’s ability to stave off pests and diseases.
I’ll be covering the latest on soil’s role in alleviating climate change in another soil news blog. Recent studies are controversial and polarizing, so I thought it would be best to dedicate a single blog on it. Stay tuned!