no-till, compost, and excessive phosphorus

Asked March 19, 2020, 10:23 PM EDT

All the research I've done on non-till vegetables gardens seems to say the same thing. They say instead of tilling in weeds in the Spring, lay down compost to keep down weeds, then plant into the compost. What I don't understand is how a no-till garden doesn't get excessive amounts of phosphorus build-up in the soil if you're using compost every year, which generally contains lots of phosphorus.

I have two existing garden plots, and both have been built up with either compost or manure or a combination of both over the last several years. The soil test reports from both plots indicate very high levels of phosphorus. To avoid using compost, I can conceive maybe planting starts in the soil, then laying down a low-phosphorus mulch (any suggestions would be appreciated). But what about vegetables I want to start from seed, like carrots? All the no-till models I've seen, just lay a few inches of compost on top of the weeds, then plant the carrot seeds into the compost, but that's not an option for me.

Any advice you can offer would be great. Thanks!

Utah County Utah

3 Responses

Hello, I do not know much about P buildup in soil when using compost in a garden. I suggest that you contact our soils specialist Grant Cardon at or Taun Beddes, the Extension horticulturist for Utah County, at

Good luck.

Mike Kuhns

Ok thank you!