I think the results from my soil testing are pretty clear. It’s not looking good for the compost…
I did the testing because my tomato plants had terribly curled and leathery leaves, tall spindly growth, and very few fruits this year. I had brought in purchased loam and compost this spring, since we have a new property and I don’t have my own compost yet and needed to new fill raised beds. For the test, I planted the same tomato seeds in samples of 4 different soils: 1) purchased compost, 2) the mixed soil from the tomato bed (a mix of purchased compost and purchased loam), 3) soil from my lettuce bed (no purchased compost or loam in this), and 4) soil from our yard below the garden beds. Representative primary leaves of seedlings grown in these 4 samples are shown in the same order above.
I think the secondary leaves of the compost-grown test plants look leathery and curled just like my garden plants. The mixed tomato bed soil is sort-of leathery, but the green’s bed plants look great. The sub-soil plants are yellow reflecting the lack of nutrients in this soil.
I find it disappointing that purchased compost is toxic to tomato plants. I live in a fairly urbanized area and the compost I bought was made from local yard waste.
Janice, who lives south of me in CT, emailed me and wrote that she contacted an organic farmer last year about a source for good composted manure and he warned about toxic manures these days due to lingering herbicides in animal feed and recommended sticking with home composting and cover crops. It seems this animal feed toxicity is often a problem now in garden composts. Herbicides used on lawns aren’t as toxic or persistent as for example, Roundup, which is what is sprayed on the Roundup Ready (GMO) corn used for animal feed. So my compost should have been OK if it was just suburban grass clippings and leaves with suburban lawn chemicals. But it seems its not OK as my tomatoes didn’t grow well at all in it. I’m really disappointed that there are so many chemicals in use that we can’t buy a safe compost product. I look forward to producing my own compost and not being in a position where I need to purchase compost or loam for my gardens.