Hello Christian,

Your soil composition is actually quite good from an agricultural and fertility standpoint. It is nominal for a Michigan mineral soil (neutral pH, good organic matter content, high phosphorus).

I think your yard is in much deeper shade than you realize. “Shade” grass needs 2-4 hours of direct sun or 5-6 hours of dappled shade in order to survive. “Sun” grass needs considerably more sunlight. I think that being under a canopy of red oak is causing the grass to decline year after year. https://soiltesting.cahnr.uconn.edu/growing-lawns-under-shaded-conditions/

As far as varieties are concerned, fine and tall fescues are the most shade tolerant grass varieties, but they still require 2-4 hours of direct sun a day. If you are not getting 2-4 hours of sun exposure, you will experience an increase in shade tolerant weeds and moss as the grass plants decline. If you wish to attempt fescue overseeding, try to determine when your dense shade area experiences the most sun (early in the season before trees leaf out, mid summer when the sun is farthest north, etc.) and attempt to seed then. Some people that try to establish grass in dense shade are committed to overseeding multiple times per year (spring and fall), every year, to constantly replace the declining grass plants.

Do you have a lawn service that cuts with riding mowers? If the lawn service drives riding mowers over your lawn when it is wet, that can lead to compaction and uneven grade levels.

Core aeration will help compaction if continued in the spring and fall each year. Ultimately what will help your turf is to thin the tree canopy, get more sunlight through it and get the soil to dry out more thoroughly. Red oaks are susceptible to a disease called oak wilt. Oak trees should only be pruned at certain times of the year to lessen the spread of oak wilt. https://www.canr.msu.edu/news/we-can-all-help-prevent-oak-wilt

If you do not want to trim the trees, you may want to consider a shade groundcover alternative instead of lawn: https://www.canr.msu.edu/news/shady_lawn_alternatives



Hello Christian,

In Michigan soils, gypsum is most readily used in soils with high salt content. It displaces the salt and allows it to wash into the subsoil without modifying soil pH. Nothing indicates that your soil suffers excess salinity. https://www.canr.msu.edu/news/gypsum_as_a_soil_additive_use_it_or_lose_it Furthermore, Gypsum is calcium and magnesium and your soil is not low in levels of either. It is true that adding calcium can assist in fighting compaction when the levels in soil are low. Per MSU, low calcium levels are below 300 ppm. Your levels are over 1400 ppm. The same with your magnesium levels. Your compaction is not caused by a lack of calcium. You do not need to apply gypsum. https://www.canr.msu.edu/news/soil_calcium_to_magnesium_ratios_should_not_concern_most_farmers

While your organic matter is in the adequate range for healthy soils, you can top dress the area with ¼ to ½ inch of compost after core aeration once a year. This can help encourage soil life (insects, microbes) which in turn help loosen soil.

Fixing compaction takes time; there is no fast or easy fix. Aeration helps. Applying compost after aeration helps. Plant roots growing into the compacted soil helps break it up. If you want to fix the compaction quickly you can remove the lawn, rototill to a depth of 6 inches or more and install a new lawn. Be careful with rototilling, since it can create a hard pan layer where the tines hit the soil. You could also try a double dig method by hand, but this would be very labor intense. https://aces.nmsu.edu/ces/yard/2007/020307.html

Are you mowing high? Longer grass blades means longer roots, which in turn, help penetrate the soil. This helps break the compaction over several growing seasons.

Here are some articles on soil compaction:

https://njaes.rutgers.edu/fs1313/

https://bexar-tx.tamu.edu/homehort/archives-of-weekly-articles-davids-plant-of-the-week/soil-compaction/

https://ag.umass.edu/home-lawn-garden/fact-sheets/compaction-cultivation