Soil Nutrients

Although you will have to add some plant food to soil when you are cultivating it, the soil already naturally contains many nutrients.

The top six or eight inches of soil usually contain enough nutrients to grow many crops.

Nevertheless, the soil still needs to be fertilized or these crops will not grow.

This is because the nutrients in the soil are often in a form that plants cannot use. A plant can only use food materials that are soluble.

The root hairs of the plant will draw up these plant foods only when they are dissolved in soil water.

Nutrients slowly become soluble through the work of the atmosphere, carbonic acid in the soil water, soil bacteria, and acid sap that is excreted by plants' root hairs.

Thus, when the soil is not cultivated, most of the food in the soil is unusable.

Cultivating allows more of the nutrients in the soil to be used immediately.

With manuring/fertilizing, you supplement the plant foods that are not immediately available, so that there are enough of these nutrients available for a profitable crop.

If the soil is kept in good condition - deeply pulverized and friable - you will need to add less manure/fertilizer.

Fertilizing the soil does not replace cultivation.

While you should provide additional plant food when necessary, it is important to make sure that your soil is well cultivated.