I planted my pumpkin seeds in a corner of my veggie beds and soon realized they needed a lot more space. Luckily I had six baby seedlings, enough to experiment with other locations and still insure that one or two will do well. I tried to transplant two of them to an empty flower bed but much to my dismay they are struggling and dying, while the four left in the garden beds are already flourishing. The lighting, temperature, and spacing are virtually the same, so the killing culprit is the soil! I decided it was time for a soil experiment. We did this in my soil classes at school, and luckily it's easy enough to do at home.
1. Gather your samples. I wanted to compare the difference between the soils in my garden beds (made up mostly of topsoil and compost) and my flower beds (unamended native soil). I dug about 6 inches deep to get a good representation of the soil at root level and gathered about 1 cup full. Try to avoid rocks and large organic matter.
The sample is best to work with if it has been dried and sifted for large clumps and rocks. My husband laughed at my mud pies drying on a cookie sheet in the kitchen.
2. Dump your cup full of soil into a large mason jar. Add about 1 tablespoon of liquid or powdered dishwashing soap, which acts as a surfactant and keeps the soil particles separate.
Sorry I started my experiment at night so the lighting is bad. You can tell just by looking at it that the garden soil is a lot darker, meaning it has more organic matter.
3. Fill the jar 2/3 full with water, screw the lid on tightly, and shake the mixture thoroughly (I went 2-3 minutes). Set them down and allow the particles to settle. Sand is the heaviest and will settle to the bottom within about a minute. Silt will settle next and could take between one and four hours. Clay will settle last and will take up to a few days to settle out of suspension.
This is how they looked the next morning. On the left, you can see some organic matter floating near the top. The sample on the right shows clearly the 3 layers of sand, silt, and clay.
My samples up close after about a week of settling. Garden above, native below.
Once the particles are all settled, its time to get out your ruler. Measure the whole depth of the soil, and then the individual parts. Now dust off the calculator. Seriously, I haven't had math since high school but even I could handle these simple calculations.To find the percentage of each type of particle, divide the part by the whole. For example, in my garden soil the sand measured 1 7/16" (1.4375) and my total soil sample was 1 5/8" (1.625) so you divide 1.4375 by 1.625 which is .885. My soil is 88.5% sand.
Once you have figured all your percentages, it's time to look at the Soil Texture Pyramid. Chart each percentage from its relative side and find where they meet in the middle. That tells you the type of soil you have!
Using the same example, my garden soil is 88.5% sand, 7.7% silt, and 3.8% clay. These three percentages meet in the loamy sand section. Loamy soils with high organic matter are well suited for growing vegetables and fruit. Because my soil is very sandy, I should continue adding lots of organic matter every year since it could leach out easily, and it will continue to improve.My native soil turns out to be a silty loam. It has poor drainage and very little organic matter. To improve it I should add more sand and organic matter, which will help both drainage and fertility. Poor little pumpkins.
If you have read this far, you may be thinking--why go through all this when the answer seems to always be add organic matter?!? Well, that's a good point. You'll never go wrong by adding compost!
There are many other important factors to of soil fertility which include drainage, nutrients (macronutrients and micronutrients), and pH. That should give me plenty of material for another time!
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