 We need to know the pH level of soil. In other words, whether the soil is slightly acidic, alkaline or even neutral. Our certain plants prefer certain soil tops. Now in front of you you have two specimens, it's exactly the same soil type, it's a loam and we're going to see whether the soil is alkaline or acidic. This is a simple way. They have got your loam about half a cup of vinegar. I'm going to pour it in and then see if anything happens. I'm going to give a quick stir, just a mix. Nothing much, but we can decide if we don't compare it with another specimen. On the right I have half a cup of barcobinate of soda. I'm going to add this to the soil. Let's see what happens now. Stir. I then know if you can see that lots of big bubbles forming. What can we deduce from this? The fact that there was a reaction between the barcobinate of soda and the slightly acidic soil gives an indication that yes the bubbles will be carbon dioxide and the soil was slightly acidic. If you look at the surface difference between the two soil types, you will see that the one on the right, the one that we tested with the barcobs of soda has got lots of fine bubbles, indicating a reaction between the barcobs and the carbon dioxide. Let's take another type of soil sand. I'm just going to randomly test it. I think that sandy soil might be slightly alkaline and let's see if it's true. Another half cup of vinegar. Pour it into the sandy soil. Oh dear, have a look. Lots of bubbles, almost foam, which is an indication of the sand being alkaline. So now we know that certain plants will grow better in sand because they prefer an alkaline medium to grow. And others might prefer the lume which is slightly acidic. Now we can test a more exact pH by using an indicator such as universal indicator. What we do is we take specimen of soil in a tissue, pour in water and mix it very well. Shake carefully. We leave it to settle so that all the solid particles will go to the bottom and the water with a dissolved substances will be clear because you know an excess of hydrogen ions will be acidic solution and excess of our drugs or ions will give us an alkaline solution. We then decant the clear solution and test it with universal indicator. Right, we give it some time to settle. Now if we look at the pre-prepared soil samples, here you can see the dish that I did with our slightly acidic soil earlier and look at the color of the solution. Indicates slightly acidic solution. In other words, it simply confirms our results. If I look you can clearly see that it's sand, the greenish color indicates a neutral to slightly alkaline solution. It's given the indication that the sand that I tested with universal indicator neutral to alkaline. You can see just for color reference, the color of a more alkaline solution. We'll see alkaline neutral to alkaline and acidic.