By Bev Johnson

Master Gardener

If you mulch, did you ever wonder why it disappears?  Jeff Gilman, associate professor of Horticulture at the University of Minnesota knows why. Here is what he says.

Our garden soil is full of creepy crawlies. Let’s start with one we all recognize, worms. In our garden, their burrowing activities reduce soil compaction, letting air and water move through the soil. As they go, they digest organic materials in the soil, breaking them down into smaller parts that release nutrients that plants can more easily use. Their castings (poop) are full of nutrients, which is why you often see worm castings advertised for sale.

Worms are good for our gardens and lawns but not for our forests. Worms are not native. They came here as eggs in soil around favorite plants from the ‘old country’ or even in ships ballast. There is growing concern among experts that earthworms are infesting our forests and devouring the litter that decays and feeds the soil. Bare soil is prone to erosion and with no litter, their tree seeds have difficulty spouting. This could change the soil and the forests themselves. It is very important not to drop fishing worms on the soil. Bag them and throw the bag in the trash.   

Petunia hates to see mushrooms in her lawn, but fungi are important to all growing plants. One very important fungus is mycorrhizal fungi. This is a naturally occurring fungi that grabs onto roots and collects minerals, especially phosphorus, making it available to the host plant. The fungi get carbohydrates in return. This is important when you dig up a plant. Be sure to take some of the soil with the plant.  The fungi in that soil are friends of that plant or tree. Taking some of the soil ensures that the plant won’t have to start all over attracting friendly fungi.

Nitrogen is the nutrient plants need most. The air is full of it especially after a thunderstorm, but it is not in the form plants can use. Rhizobium bacteria do that conversion. This bacteria lives in the roots of the legume family (beans, peas) and some trees. They, along with some other nitrogen fixing bacteria, are important to healthy soil.

To ensure healthy soil, use as little synthetic fertilizer as possible. It does benefit the soil as it adds extra nutrients, but synthetic fertilizer is packed with salts. Large amounts of it will make the grass greener but eventually, it will damage the soil, and the lawn will be less able to survive stress.  If you must use fertilizer, use organic ones. An excellent fertilizer for lawns is corn gluten meal. It has a small amount of nitrogen so it may take 2 to 3 years to see the results.  It is also a pre-emergent seed killer. Use it where you have annual crabgrass. Apply in spring when the daffodils first show color, then again when the lilacs bloom. The soil is the proper temperature at these times for it to be the most effective as this is when the grass seeds are just emerging. The other use for corn gluten meal is in animal feed. It adds protein.    

The moral of the day is; feed the soil and it will feed you. And never drop your fishing worms in the woods.