How do we generally determine what's a good soil? (Beginner level)
"I'm a beginner and i wish to start gardening but i don't even know what soil is! I only know it dirties my laundry and there are many worms inside!" - If this description fits you, then you are at the right page.
We all have an idea that soil is capable of supporting plants. But how exactly do we define soil and what function does it have to plants?
Soil is a natural body made up of solids, liquids, and gases that contains a complex mixture of minerals, organic matters, water, air and other living organisms. Its general role in horticulture is to serve as media for growth of all kinds of plants.
To have some basic judgements by touching and seeing, here are some general tips:
Tip #1: Soil colour
By looking at the soil colour, it provides a clue on the soil content. Sometimes, you can assess the moisture level, drainage properties and porosity just by looking at the colour too.
Usually, a darker colour indicates more presence of organic matter available in the soil. A darker colour also indicates moisture content. By understanding the different types of media available in the market, you can tell their presence by the colour too. For example, the presence of perlite will indicate whitish substances.
Tip #2: Soil texture
Soil texture refers to the size of the soil particles/pores, with sand as the largest, silt, and clay as the smallest. Most soils contain a mixture of all three groups. This means that if there is a relative proportion of sand silt & clay, it would be the best!
And you guessed it, there is also a chart for reference!
Here's a fun table just for your information too:
Tip #3 Soil density
How heavy the soil can determines how closely packed the particles in the soil is. If your density is too high, it can restrict or even prohibit root growths. This means that the porosity (spaces between the soil particles) is too tight, and it may affect the total volume of water a soil can hold. An ideal soil would consist approximately 50% of pore spaces.
Fun Fact: Ideal bulk density = 1.33g/cm3 (Yes, we have a formula for it)
Tip #4 Soil Water Movement & Soil Water Holding Capacity
*Soil water movement refers to soil infiltration and percolation rate - how fast the water goes down into the soil profile
*Soil water holding capacity refers to the ability of soil to hold water & not losing it to gravity pull
If the water drains out too fast, you'll wonder if the soil even gets any water?
If the water drains out too slowly, you should be wondering if the soil is flooding?
By now you would have guessed that the these factors are controlled by the size of the pores, which is why it is so important to have good water holding capacity and good drainage as a factor for good soil. The larger the pores, the faster the water movements (infiltration and percolation rate improves).
*Percolation rate is the process of water moving downwards into the soil profile
Next, we will ask ourselves what is the actual amount of water actually present in the soil? This is what we call soil moisture content.
Here's the tricky part! When the soil appears to be absorbing A LOT of water, it does not mean that it is a good thing! Because when the soil reaches permanent wilting point, it means that the water is held so tightly by the soil, it is made unavailable to the plants. It is important to have available water for plant growth.
When people tell you to water your plants continuously for a while even when it "wastes" a lot of water, it is because it will allow the soil to reach its saturation point - the point when your soil cannot hold anymore water and excess is drained out via gravitational forces. This ensures that the soil has maximum amount of available water that it can hold for the plant.
So Panana, how would i know when my soil reaches the permanent wilting point?!
Ans: When your soil can't absorb a single water, or when the pores are so tight no water can penetrate inside!!
Of course, there are also many other ways and tips to identify or test for a good soil. But in general, these are enough for you to identify as a beginner.