Welcome to our soil science information page.
Soil is not just dirt.
Great vegetable gardens come from great soil. So, what makes the soil great?
1. Minerals from sand, silt and clay, 45%*
2. Water, 25%
3. Air, 25%
4. Organic material, 5%
The biggest particles in soil are called sand. The clay particles in the soil are very small and have an electrical charge. The size of silt is between sand and clay. Sand allows water to drain, silt is fine enough to create small spaces for air, and clay holds water and nutrients. If there is too much sand, water drains out too quickly and plant nutrients are washed away. If there is too much clay in a soil, the water cannot drain out and plant roots suffocate from lack of air. Loam soil is a good mixture of the three.
The percent of sand, silt and clay give the soil its texture. (See the Soil Triangle.) To discover the texture of your soil, click on the button below to follow the flow chart.
SOIL CHEMISTRY: What is pH and why is it important?
The way plants take up nutrients is through chemical reactions that take place in the water around the plant roots. pH is a measure of the acidity or alkalinity of this water in the soil. The best garden soil is slightly acidic. The range of pH goes from 0 to 14 where 7 is right in the middle or "neutral." Values less than 7 are acidic, values greater than 7 are alkaline. The best soil for vegetable gardening is slightly acidic with a pH measure of 6.5. At this level, plants can take up the most nutrients. Click on the button to learn more.
SOIL BIOLOGY: Who lives in the soil?
Great soil also needs the animals that live there!
Worms and bugs start the decomposing process.
Microbes are the recyclers of organic matter that work on a very small scale to create the nutrients plants need to grow and reproduce.
Fungi work with plants to help them get these nutrients from the soil.