Boost Soil Health for Great Gardens
By George Giltner, Advanced Master Gardener
How do you improve soil health? Simply, manage the life in the soil. It is just like growing grazing animals, however the life forms are much smaller. You need air, water, food, a suitable temperature, and certain other environmental factors that favor their growth.
Air, yes the soil needs to breath. Gases must be able to freely move through the soil for healthy soil. A good healthy soil is fluffy and light with aggregates that are formed from fungal glomalin, the “super glue” of soil. This mycorrhizal glue accounts for 27% of the carbon in the soil which may last up to 40 years. It provides soil structure to harbor beneficial microbes, retain water, and reduces soil compaction. The mycorrhizae form mutualistic relationships with plants in which nutrients and water is transported. Therefore the gardener or farmer would want to encourage this fungal growth.
The best way to encourage mycorrhizal growth is with no-till practices. Tilling or plowing chops up the fine mycelial strands between the plant and surrounding soil which is detrimental to fungi and plant. Cover crops (especially mixed plant types), less use of cabbage and mustard family plants that do not use mycorrhizae, and less phosphorus applications will result in favorable conditions for glomalin-producing fungi.
Know your water! Check the pH of the water that you are irrigating with. Some regions have major problems sodium carbonates and bicarbonates which raise the pH up to the high 8’s and even above a 9 pH which is above EPA waste water limits. This can cause soil compaction, reduced plant grow, and salting of the soil. Also use a water meter to test soil moisture instead of guessing. Sometimes we become very busy, so use drip irrigation on a timer as the best way to control watering.
The soil needs to be fed. Composted animal manure to a plant is like giving steak to a starving teenager. The mineral and organic nutrients of good compost enhance the soil growth of bacteria to worms to soil arthropods. Each time these critters poop or die, their wastes become available as nutrients to plants and other organisms of the soil. Cover crops are another major food source of the soil. As these crops grow, they provide exudates of carbohydrates that feed beneficial microbes around their root systems. This activity initiates a soil food chain. Also crop residues are also beneficial to decomposers in the soil. The soil should never be without food (some organic matter to feed on). Yet some people leave the soil bare for months until spring, but by then most of the soil life has starved or moved.
Soil temperatures will affect microbial populations. Summer temperatures on bare ground can exceed 120 deg. F. With this heat extreme, plants and soil literally have the moisture and life cooked out. Photosynthesis goes downhill at 95 deg. F. In order to cool this heat environment, add a two inch mulch insulation layer to reduce soil temperature 20 to 30 deg. F. Another approach is to have multiple layers of leaf height to shade the soil from all angles. This will result in a 20 degree cooler soil.
The secret of good soil is to treat it like a living organism. As it grows – so does your plants.