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Garden soil test results #798562

Asked June 29, 2022, 1:13 PM EDT

I have sandy soil but have added black dirt years ago and the last few years have mulched with wood ashes, deep layer of leaves (chopped) and compost. A couple times, I added manure in the fall but that's been quite a while. I have lived here 33 years. My vegetable garden has always been on the weaker side of productivity, particularly peppers. Plants stay small and get very few peppers. Since mulching with the leaves, my tomato plants are better but still not great. The soil looks much better. It is dark and not compacted. There are many earth worms in it (no jumping worms). See the attached soil test. Phosphorus levels are over 100. I'm wondering what has caused such high numbers. And the best fix going forward. I'll stop using wood ashes. This year, I was wondering if I could use the nettle fertilizer that I brewed for the vegetables. Any insight into all, I'd love to learn. Thank you - Elaine Mustari

Isanti County Minnesota

Expert Response

Excess soil phosphorus is generally not a problem for plants  in MN but it is a problem for lakes and streams.  Phosphorus buildup in urban gardens found that repeat applications of compost led to an average phosphorus soil test value of 80 ppm (parts per million, Bray P test). This number by itself may not mean much, but consider that 80 ppm of P is nearly four times higher than what the UMN Extension considers “very high” available P for crop production. Manure also raises phosphorus levels. You could use a combination of cover crops (with legumes for N) and blood meal for your garden nitrogen. Blood meal (12.5-1.5-0.6) releases nutrients over a period of two to six weeks. Fish fertilizer is (5-1-1). Plants lacking nitrogen will show yellowing on older, lower leaves. Excess nitrogen can cause excessive leafy growth and delayed fruiting. Soil pH can be reduced by adding elemental sulfur. Most garden plants tolerate the pH of your soil but potatoes require a much lower pH. Lack of sulfur on sandy soils can cause stunted, spindly growth and yellowing leaves. My guess is that you need more nitrogen.
Pat M MN master gardener and TCA Replied June 29, 2022, 2:48 PM EDT

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