Everything that I read about soil makes me wonder if I've been an idiot my whole life, and didn't even know it. Some of the things they talk about in these complex articles, books, and blogs makes perfect sense to me, but putt it together is another story.
Perhaps understanding this business of organic matter v organic material, physical indicators (structure, depth, infiltration, bulk density, water holding capacity), chemical indicators (pH, electrical conductivity, extra nutrients), and bioligical indicators (microbial bomass, minerliazable nitrogen, soil respiration) - perhaps all of those things make perfect sense to some people. I am not one of those people. So, I've put together a bit of what I do understand, and I plan to keep updating it as a I begin to understand more. That being said, this is not a complete guide to evaluating your soil, it's a guide to evaluating soil, as I understand it, at this time. I hope it helps! - Stephanie
Step 1: Understanding your Soil Texture
Dig into your soil with your bare hands. Feel the soil, and pinch it between your fingers. You want to know if your soil is clay, sandy, or loam.
- Clay Soil is going to feel smooth and dense when you roll it in your finger, and it's going to maintain it's shape when you roll it into a ball.
- Sandy Soil is going to feel gritty and grainy when you roll it in your fingers, and it's just going to fall apart when you try to roll it into a ball.
- Loam Soil is a combination of clay and sandy soil, and this is ideal for your garden. It will hold some sort of shape when rolled into a ball, but will easly fall apart and crumble if it's distrubed.
Step 2: Add Organic Matter
If it tuns out that your soil is mostly made of clay, that's okay! We can take clay soil and make it more loamy by addings leaves, peat moss, and compost. The clay soil will hold tight to water, but it won't want to share with your roots. If clay gets too dry, it becomes hard and cracks. The organic matter will help the clay material to breathe - this means that your plants can access the soil and nutrients that they need to grow big and strong!
If it turns out that your soil is pretty sandy, that's okay, too! The problem with sandy soil is that it does not retain the water/moisture that plants need to thrive and survive. With sandy soil, the answer is the same: add organic matter. Adding organic materials that are well composted to your sandy soil will help it to retain water, and keep nutrients available for your plants. If your clay soil still seems to stick in a ball when you try rolling it up, you can add grit to the soil to help improve the water content and drainage.
If you have loamy soil, that's awesome! You'll need to continue to read to ensure that you maintain the necessary nutrients in your garden, but your soil will do well at storing water, and making nutrients available to your plants
Step 3: pH Testing Your Soil
The pH of your soil matters, because different plants prefer different pH levels for optimal growth. For example, Tomatoes like their soil at a pH of 5.5-7.5, and broccoli is more particular and prefers a pH of 6.0-7.0. Knowing the pH of your soil will help you to determine what plants will grow best in your soil. If your soil pH doesn't quite meet the expectation of whatever you've intended to plant, you can modify the soil pH by adding different nutrients (see Step 5) The Old Farmer's Almanac has a great chart for the pH that is preferred by a variety of different plants.
The best way to test hte pH of your soil is with a soil testing kit. I like to keep it simple, so I go with the Rapitest Soil Test Kit because it contains tests for pH, Nitrogen, Phosphorus, and Potassium. (I know we haven't talked about Nitrogent, Phosphorus, and Potassium - but we will in the next step). With this test, you'll simply combine some of your soil with water, and then pour out the excess water. Then you need to dissolve one of the included test capsules and use the provided color chart to determine your soil's pH level.
Step 4: Nutrient Test Your Soil
There are a number of nutrients that are necessary to successful gardening. Nitrogen, Phosphorus, Potassium, Magnesium, and Iron are just a few. The 3 most important nutrients that you need to keep track of are nitrogen, phosphorus, and potassium. That's why the Rapitest Soil Test Kit includes tests for those nutrients, in addition to pH.
Nitrogen is an absolute necessity for plants to be able to properly perform photosynthesis. This is a big deal! Photosynthessis (if you don't know) is the the plants way of creating energy for growth and production.
Phosphorus is used by plants for root growth, the development of stem, fruit and seeds. Phosphorus is also necessary for the plant to be able to resist disease, and overall plant health.
Potassium is also frequently referred to as "potash." Potassium has a great deal to do with the development and flavor of your fruit or vegetable... so it matters! Potassium also helps the plant with resisting disease and promotes vigorous growth.
Step 5: Add Nutrients and Modify the pH of Your Soil
I have not fully wrapped my mind around this, as of yet, but I want to give you a solid overview on the way that you can use different types of organic matter to your soil in order to make adjustments to the soil's pH, and nutrient levels. This chart comes from The Ultimate SELF-SUFFICIENCY handbook (click to enlarge):