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Soil

Fertility

Inherent or Natural Fertility
Acquired

N (nitrogen), P (phosphorous), Ka (Potassium) enable good growth and yield.

Different ph types suit different plants.

Chemical Fertilizer risk

Overuse or repeated use of fertilisers can result in an ultimate decrease in soil fertility along with acidification of the soil.

Terra preta

was made (450 BCE - 950 CE) by adding a mixture of charcoal, bones, broken pottery, compost and manure to the low fertility Amazonian soil. A product of indigenous Amazonian soil management and slash-and-char agriculture. The charcoal is stable and remains in the soil for thousands of years, binding and retaining minerals and nutrients.

Contrast with common soil

Deforested arable soils in the Amazon are productive for a short period of time before their nutrients are consumed or leached away by rain or flooding. This forces farmers to migrate to an unburned area and clear it (by fire).

Terra preta is less prone to nutrient leaching because of its high concentration of charcoal, microbial life and organic matter. The combination accumulates nutrients, minerals and microorganisms and withstands leaching.

Degradation

Salination

See irrigation page.

Acidification