Hi I'm Tricia an organic gardener I grow organically for a healthy and safe food supply, for a clean and sustainable environment, for an enjoyable and rewarding experience. Testing your soil is an important part of growing happy healthy plants laboratory testing is really the most accurate way to test your soil and it should be your starting point but home kits are a great way to monitor the effects of your fertilization.
The main nutrients plants need are nitrogen for vegetative growth, phosphorus for root and flower development and potassium for vigor soil pH is the fourth important measurement because it determines whether or not a plant can use the available nutrients. For more information about the vital nutrients what they do and how to add them to your soil if you have a deficiency watch our "Fertilizing Organically" video. Your soil test is only as good as your sample so take a good sample you want to use a clean stainless steel tool like a trowel or if you're doing a lot of sampling you can get this soil sampler. For more information on taking a good soil sample and the type of testing a laboratory performs check out our "Soil Test" video take several samples from a single area and go down about six to eight inches in depth and then mix the samples together avoid touching the soil with your bare hands put the soil in a clean plastic bag stainless steel or paper container. Do a soil test for each distinct area in your garden for example I'm going to do a separate soil test for each one of the raised bed. Spread the soil out on a sheet of dry paper and let it dry for about twelve hours don't try to hurry it along by putting it in the oven. Well my soil is dry and now it's time to start my test crush the soil and sift it through a sifter or a screen to get an even texture and remove any debris or rocks. I'll be using a La Motte soil test kit be sure and read all the material safety data sheets and follow the instructions very closely some of the reagents can irritate your skin or eyes so be sure and wear your gloves and your safety goggles.
First i'll do the ph tests fill one of the test tubes to the fourth line with the ph indicator use the point five grams spoon and add three scoops of soil put on the cap and shake gently for one minute. Just set the test tube down and let it settle for about twelve minutes now it's time to compare my pH to the color chart to get an accurate reading of the color chart. Stand with the sun behind you and hold the test tube about a half an inch in front of the color card looks like i have a pH of about eight point zero. On to the nitrogen testing take a clean test tube and fill it to line seven with the nitrogen extracting solution and again were going to add three of these scoops which are point five grams each put on the cap and shake gently for one minute remove the cap and let it settle. Once it settled use a clean pipette to move the clear liquid to another clean test tube to line three be careful not to pull up any soil add two point twenty five grams scoops of the nitrogen indicator powder. Cap it mix gently and wait for a pink color to develop. My nitrogen test indicates that i have trace amounts of nitrogen onto the phosphorus test fill up the test tube to line six with the phosphorus extracting solution put in three scoops of point five grams of soil gently shake and let settle once it settled use a clean pipette to move the clear liquid to another clean test tube to line three add six drops of phosphorus indicator reagent cap and mix then and one phosphorus tablet. Be careful not to touch the tablet mix into the tablet dissolves in the liquid turns blue well looks like I have plenty of phosphorus. The last nutrient I'm going to test is the potassium fill a clean test tube to line seven with the potassium extracting solution this time for the potassium we're gonna add four scoops and then we're gonna shaken vigorously not gently again allow it to settle and move it to a clean test tube with a pipette it needs to be filled to line five so you might have to prepare more soil add potassium indicator tablet and mix gently until the tablet dissolves and the liquid turns purple add the potassium solution one drop at a time mix between the drops and keep track of how many you put in stop adding drops when the liquid turns from purple to blue. I had to add twenty five drops to get the potassium color light blue i'm really low on potassium fortunately the La Motte soil test kit comes with three fantastic guides that you can read to determine what to do next in amending your soil. So do a soil test and grow organic for life!