a home test (https://www.amazon.com/dp/B01HQXF0PS?psc=1&ref=ppx_yo2ov_dt_b_product_details). Good to know they are not that accurate. However the very stunted growth, yellowing leaving from the bottom up, and curled leaves indicate to me a nutrient deficiency. The tomatoes in bags with straight potting soil are doing much better.