Fertilizer is used to augment the nutrients found in natural soils, or to adjust those soils to better suit the growing needs of selected commercial crops. Fertilizer can also be used as an additive to return soils to productive use or return nutrients removed through farming back to the soil. Most fertilizers used are petroleum based (Nitrogen) or mined from non-renewable sources (Phosphorus from phosphate rock and Potassium from potash). While Phosphate rock is currently mined in North America, the world’s largest source of phosphate rock is Nigeria. Canada and Russia are the two dominant producers of potash.
Soil amendments are also used to improve soil pH levels and add organic matter – the latter helping to improve water, oxygen and nutrient penetration to the plant root structure.
Asia has commercial production of Nitrogen, limited phosphate production and limited potassium production.
Soils are also “adjusted” for a number of other crop needs including soil pH, sulfur and other micro nutrient levels. Generally, soils are neutral, but the pH begins to fall with continued farming. Good soil management requires the application of a pH adjusting material such as lime in order to keep the soil pH in the range that supports good crop growth. Failure to properly adjust the soil for pH will negatively impact crop yields.
The aggressive and continued application of dried biosolids to fields along with poor tilling prior to seed application, also causes soils to become compacted – negatively impacting soil tilth. Soil compaction limits plant root oxygen intake, which negatively impacts crop yields.