In past logos I have used these two colors: #70ab29 and #de9426. You are not required to use those colors.
To give us an idea of the overall feeling of your brand, let us know which styles you lean towards
Soils have horizons like this image shows. It might be nice to incorporate that concept into the logo design.
You can review my website at http://www.soilhub.com. Since we are an education company, incorporating symbols related to learning might be interesting. Things like graduation cap, owl, chalkboard, light bulb, etc. Since we have soil in our name, a character like a worm or mole or other creature related to soil might be interesting too.