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Moms Team: u.s. Dietary Reference Intakes (Dr Is) for Minerals
Here is a chart with useful information on the minerals you need to be healthy. Includes "functions" and "sources" of calcium, iron, magnesium, sodium, potassium, zinc, copper, selenium, chromium, manganese, iodine, fluoride, and phosporus.
BBC
Bbc: Gcse Bitesize: Making Fertilizer
This lesson focuses on fertilizers including how they replace nitrogen, phosphorus and potassium in the ground; how the plants get the nutrients; a table showing examples of fertilisers, their formula, and the essential elements they...
Other
What Is a Soil Test?
The North Carolina Department of Agriculture explains soil testing, taking a soil sample, and analyzing the results.