Did you know that you can get a rough estimate of your garden soil quality without investing in a soil test kit or pH tester? Sure, professional soil test kits will give you more accurate readings of the soil pH levels and chemical nature of your soil, but you can still get pretty good guesstimates with a few natural testing methods.
Test pH Soil Quality with Vinegar and Baking Soda
A ludicrously simple way to test soil pH levels and soil quality is to take two dry soil samples, add distilled water to each, then sprinkle one with vinegar and the other with baking soda. If the vinegar soil sample fizzes, the soil is alkaline. If the baking soda soil fizzes, the soil acid.
Now, if the vinegar test pegs your soil as alkaline and you're in an area known for high free lime (a.k.a. calcium carbonate) levels in the soil (like Colorado), you may want to go ahead and invest in an inexpensive test kit. I say this because it's really difficult to "fix" the pH levels of soil with high levels of free lime. So, before spending loads of money on soil amendments like sulfur and sphagnum peat moss and finding out they don't work, you might want to spend a few bucks on a professional kit that can give you a better idea of your soil quality and conditions.
How Weeds Can Indicate Soil Quality
Just like flowers and vegetables, different weeds have different soil needs, so a free and easy way to eyeball your soil quality is to see what weeds keep popping up in your garden. For instance, if the weeds that favor your garden are yarrow, ragweed, dandelions, thistle, crabgrass and plantain, you can bet the quality of your soil is pretty poor. More likely than not, your soil is low in important nutrients (like the big three: phosphorus, nitrogen and potassium) and you'll have a harder time growing common greens and vegetables. On the other hand, if your garden grows a lot of pigweed, lamb's quarters, foxtails and common chickweed, you've probably got pretty fertile dirt with well-balanced soil pH levels.
How Plant Health Can Indicate Soil Quality
Another free, all-natural way to test soil quality is by observing plant health. While some soil nutrient deficiency symptoms are too general to diagnose without a real soil test kit, others have clear symptoms that are easy to recognize. For instance, yellow or curled leaves with green veins indicate soil that is deficient in iron or nitrogen. Soil deficient in magnesium will often result in thin, brittle, bronzed or purple/red leaves. And black spots on beets and black rot on turnips indicates soil deficient in boron.
Now, if your soil quality seems "fine" and you're still having problems producing a good crop, you may want to check ideal pH values for herbs and ideal pH levels for garden vegetables to make sure you're growing the right crops for your soil pH levels.