Excessive P, K, Mg, Ca
I’ve found information about soil nutrient levels that are too low, but not about those that are excessive. The soil test results for my raised beds, where I plant vegetables, were excessive for P (176), K (248), Mg (409), and Ca (387). PH was 7.2, buffer pH was 7.87. Organic matter was 10.3%, which is also high. I add only compost (leaves, egg shells, coffee grounds, other plant matter). I tend to have spotty germination of greens and root vegetables, such as turnips and beets. Could my soil be the problem?
Montgomery County Maryland
Hi- the excessive levels of the listed nutrients will not negatively affect your soil or crops. It just means that you won't have to add these nutrients in the form of fertilizers and composts. You could back off on organic matter additions. The key to maintaining soil health at this point is to grow a wide variety of plants for as many months of the year as possible (living roots are the key to maintaining an active soil foodweb).
All of these crops grow best in the 6.0 - 7.0 soil pH range. However, we do not think that a 7.2 soil pH would inhibit the germination or growth of any of these crops. The problems you are observing could be in response to soil temperature, seed age and quality, planting too deeply, seed and seedling predation by insects and other animals, excessively wet soil, soil pathogens, etc.
Thank you very much.