Soil III: Nutrients

Now that the soil is amended, we can take a closer look at the nutritional value of the soil.

17 nutrients in total are necessary for plant life, but only 3 are needed in large quantities. Often called the primary macronutrients, these 3 are nitrogen, phosphorus, and potassium - or, N-P-K, respectively. When you see 3 numbers on a fertilizer bag, such as 10-10-10, this is what those numbers are referring to. The product's N-P-K numbers reflect each nutrient's percentage by weight.

Other elements are just as critical for survival, but are needed in much less quantities, such as iron or calcium. Some fertilizers will be fortified with other nutrients depending on their advertised application.

N-P-K needs frequent replenishing.

Different plants require different amounts of each nutrient. You can test your soil, but most of the time, amending with compost/manure is fine for most uses. Apply fertilizer after testing soil and assessing specific plant needs.

Nitrogen
Phosphorus
Potassium