How to lower nutrients in the soil to optimum levels?
Question:
I have eight raised beds (8′ by 4′) and all have above optimum levels for phosphorus (79.1), calcium (79.3), boron (1.5), manganese (11) and zinc (98) according to my last soil test. What I want to know is how to lower these nutrients and micronutrients to optimum levels?
Answer:
Thank you for your question. I have reviewed your full soil test results and checked in with the Soil Testing Lab. The nutrient levels measured in your soils, though higher than needed for crop growth, are not at levels where we would expect to see problems. So, there is no need to take specific action to lower these levels.
The zinc level is particularly high, but that could be from contamination during soil sampling. We sometimes see that when a galvanized bucket or tool was used during soil sample collection. The high phosphorus level coupled with the high organic matter suggest that compost has been used in the past. To prevent further nutrient accumulation (especially phosphorus), skip the compost for a few years and just apply the nutrients that are specifically recommended on the soil test results. Both organic and conventional nutrient sources are listed there. The UMaine Soil Testing Lab has some additional resources about micronutrient management and interpreting soil test results if you are interested.