Fertilizer - Inorganic Commercial Fertilizer - Problems With Inorganic Fertilizer

Problems With Inorganic Fertilizer

Common agricultural grade phosphate fertilizers usually contain impurities such as fluorides, cadmium and uranium, although concentrations of the latter two heavy metals are dependent on the source of the phosphate and the production process. These potentially harmful impurities can be removed; however, this significantly increases cost. Highly pure fertilizers are widely available and perhaps best known as the highly water soluble fertilizers containing blue dyes used around households. These highly water soluble fertilizers are used in the plant nursery business and are available in larger packages at significantly less cost than retail quantities. There are also some inexpensive retail granular garden fertilizers made with high purity ingredients.

Oregon and Washington in U. S. have fertilizer registration programs with on-line databases listing chemical analyses of fertilizers.

The most widely used inorganic fertilizer is super-phosphate and its double and triple strengthed derivatives double super and triple super. Super phosphate was first developed by Lawes at the Rothamstead Agricultural Research Institute in England in the early 19th Century. Lawes added sulfuric acid to conventional rock phosphate containing the mineral apatite, a calcium fluoro-phosphate. The resulting water soluble phosphorus was able to significantly improve yields on a variety of crops at the Rothamstead Centre and the Superphosphate industry was born. Unfortunately over decades of subsequent usage - it became clear that the solubilisation of fluorine also occurred in the process and this had the same effect as the other halogen sterilants(chlorine, bromine, iodine) over time - soil sterilization. Effectively farmers unknowingly became 100% dependent on 'bought in' water soluble, inorganic fertilizers since the sterilization of soil microflora including its micorhizza, reduced the availability of other natural and trace minerals within the soil. This to some extent explains the resurgence of interest in organic and particularly 'biodynamic' farming systems since these systems replace the essential soil organisms so essential to converting soil minerals into plant available (but rarely water soluble) nutrients. They do this by a variety of processes including chelation whereby essential minerals become plant available - as measured by weak citric acid extraction techniques. Hence the citric acid solubility of phosphate rocks has emerged as a measure of plant availability and enabled so-called 'reactive' phosphate rocks to be used as fertilizer minerals. These should not be confused with high fluorine apatite rocks in which the fluoride content performs a similar function to its role in hardening teeth enamel, i.e. immobilizing phosphorus. This explains the oceanic origins of many of these high fluorine rocks (Christmas Island, Ocean Island) since the fluorine absorbed from the sea has prevented what were originally massive deposits of bird guano - from being leached from the coral based limestone rocks on which they were originally deposited.

Also regular use of acidulated fertilizers generally contribute to the accumulation of soil acidity in soils which progressively increases aluminium availability and hence toxicity. The use of such acidulated fertilizers in the tropical and semi-tropical regions of Indonesia and Malaysia has contributed to soil degradation on a large scale from aluminium toxicity, which can only be countered by applications of limestone or preferably magnesian dolomite, which neutralises acid soil pH and also provides essential magnesium.