Monday, October 3, 2011

Soil Lab

The 12 Soil Orders

The twelve soil orders include:
1) Gelisols
2) Histosols
3) Spodosols
4) Andisols
5) Oxisols
6) Vertisols
7) Aridisols
8) Ultisols
9) Mollisols
10) Alfisols
11) Inceptisols
12) Entisols

Each soil is unique in the nutrient levels and where it is located in the world.

The soil I think is most interesting is Oxisols. Oxisols is a very weathered soil. You can find it in intertropical regions of the world. They are rich in Iron and Aluminum minerals and deficient in most other minerals. Globally, Oxisols only take up approximately 7.5% of ice-free land area. Hawaii is the only place in the U.S. where this soil can be found-approximately 0.02% of land area in U.S. There is low fertility within this soil but this can be compensated with treatments of lime and fertilizers. There are five suborders within the type Oxisols: Aquox, Torrox, Ustox, Perox, and Udox.

For the lab last Monday, we discussed the soil in the community garden behind Centenary United Methodist Church by Mercer in Macon, GA. They have set up a community garden for people to be educated on food and gardening, create a network for people in the local food system, and support and sustain food system in the Macon area by celebrating local food culture. Mark Vanderhoek from Mercer University is one of the main leaders of the Macon Roots organization.

In our lab, we took a split-spoon corer sample which gives you a soil profile. This allows you to see the depth of the soil and the type of soil the further you go down in depth. The change of color of the soil as well as the change in texture of the soil can be seen telling you about the type of soil and change of soil type over time.

We also took soil sieves which is a type of sifter that has stacks of mesh/grate over the bowls to allow sample of soil to be sorted out to see the different types of soil. The bigger holes in the mesh/grate are at the top and the grate gets smaller as you go down. The larger grains of soil are clay. The middle sized grains are silt and the small-fine grains of soil are sand. You can decide what type of soil it is through the percentages of clay, silt, and sand within the soil sample. This is found through the Soil Texture Diagram.

Lastly, we used the Dichotomous Key for Soil Samples to determine the classification of a soil sample we collected. Our group found our soil to be a Loamy sand because it remained in a ball when squeezed and it did not form a ribbon of uniform thickness and width when pressed between the thumb and forefinger.

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