Hi Aaron, thank you for using Ask Extension.

Thanks for sharing your soil test results. Your soil is sandy, low in organic matter, and low in phosphorus and potassium. Because the garden is already planted and contains many different vegetables, the recommendations below use simple, light, universal rates that are safe for all crops.

1. Fertilizer (safe for mixed vegetables)

Apply a light feeding of:

3–5 pounds of 12‑12‑12 per 1,000 square feet once.

Apply it 4–6 inches away from plant stems and water it in. This gentle rate gives your garden a boost without over‑fertilizing crops that need less nitrogen.

Because your magnesium level is already above optimum, avoid fertilizers that contain magnesium, such as dolomitic lime, Epsom salt, Cal‑Mag products, or K‑Mag.

2. Organic Matter (the most important improvement)

Your organic matter level is low and improving it will help with water retention and nutrient holding in sandy soil.

Apply 1–2 inches of finished compost as a surface mulch.

Compost contains very little magnesium and is safe for all vegetables.
Other safe mulches include shredded leaves, clean straw, and partially composted wood chips.

Avoid manure during the growing season.

3. Later in the Season and Next Year 

● If plants pale or slow down later this summer, you may apply another very light feeding of 2–3 lb/1000 sq ft of 12‑12‑12.

● In fall, add more compost and consider a simple cover crop (oats or rye).

● Next spring, before planting, apply 10–15 lb/1000 sq ft of 12‑12‑12 and mix in compost again.

These steps will gradually improve your soil’s organic matter and nutrient‑holding capacity.

Check out the following links:

More reasons for soil testing - Agriculture

Smart fertilizer use: Vegetable gardens begin with soil management plan - Gardening in Michigan

soil_test_interpretation.pdf

I hope this helps.