Phosphatic Fertilisers

Phosphorus-containing fertiliser materials were in use for many centuries before their action was identified with the presence of the elanent Hsh and animal manures were employed several thousand years ago and the Carthaginians were nsing bird dung in 200 bc. In the twelfth century, guano was used by the Arabs and the Incas. 

English farms used bones in the seventeenth century, and waste bone and ivory chippings from button and knife mannfacture in Sheffield (GB) were used locally around 1750. Bones were used as fertilisers in France and the United States in the early part of the nineteenth century and increasing qnantities (often from battlefields) were imported by Great Britain np to abont 1850. 

Animal manure, bones, bone ash, bone meal, guano and dried blood are stiU used in a relatively minor way, althongh their phosphate content is lower, or is less readily available than in the mann-factured prodncts to be discussed below. 

In 1842, British patents for the mannfacture of superphosphate by the action of sulphuric acid on bones were taken out independently by J.B. Lowes and J. Murray [28-31]. This led to the world s first fertiliser factory at Deptford, Kent, England. A few years later superphosphate manufacture conunenced in the United States, but it was not until about 1855, however, that the work of Lowes 

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Ligno sulfonate—metal complexes are weaker complexes than those formed from amine-based complexing agents such as ethylenediaminetetracetic acid (EDTA). They are compatible with most pesticides /herbicides, but thek use in phosphate fertilisers is not recommended. 

The method can be applied to the determination of phosphorus in a wide variety of materials, e.g. phosphate rock, phosphatic fertilisers and metals, and is suitable for use in conjunction with the oxygen-flask procedure (Section 3.31). In all cases it is essential to ensure that the material is so treated that the phosphorus is converted to orthophosphate this may usually be done by dissolution in an oxidising medium such as concentrated nitric acid or in 60 per cent perchloric acid. 

One of the problems is that the phosphate fertiliser allowed by the organic regulations is rock phosphate, and research in Austria has shown (Lindenthal, et al., 2000) that the application of rock phosphate had virtually no effect on subsequent crop yields. 

The practical significance of such competition evolves from the experience that silicate and (anionic) humics can increase the efficiency of phosphate fertiliser because these compounds occupy sites suitable for phosphate adsorption (Kingston et ak, 1968 Schwertmann, 1995). Hydroxyl is another anion that competes effectively with adsorbing anions, owing to its location in the inner Helmholz layer. The release of adsorbed phosphate after liming a soil or after inflow of acidic surface soil into weakly alkaline surface waters due to erosion, can be considered as the result of competition between OH and phosphate ions. 

Lim, H.H., Gilkes, R.J. and McCormick, P.G. 2003. Benefication of rock phosphate fertilisers by mechano-milling. Nutrient Cycling in Agroecosystems 67 177-186. 

Vanadium leaches soil from a large number of diverse sources, including waste effluents from the iron and steel industries and chemical industries. Phosphate industries are also a major source of vanadium pollution because vanadium becomes soluble along with phosphoric acids when rock phosphates are leached with sulfuric acid. Vanadium is present in all subsequent phosphoric acid preparations, including ammonium phosphate fertilisers, and is released into the environment along with them. Other sources of vanadium pollution are fossil fuels, such as crude petroleum, coal and lignite. Burning these fuels releases vanadium into the air, which then settles in the soils. 

The presence of elements known to have adverse health effects in humans such as lead and arsenic is obviously undesirable in food. Environmental sources are the main contributors to contamination of food with most metals and other elements. Some elements (e.g. arsenic) are present naturally but the major sources of other elements (e.g. lead) in the environment are from pollution from industrial and other human activities. The presence of metals and other elements in food can also be the result of contamination from certain agricultural practices (e.g. cadmium from phosphate fertilisers) or manufacturing processes (e.g. tin in canned foods). 

Phosphate fertilisers also contain a number of other elements found in the parent phosphate rock (Bowen, 1979 Bockman et al., 1990 Jackson and Alloway, 1992). Cadmium originating from sedimentary rock is particularly undesirable, and processes for the removal of Cd from such fertilisers are being developed (Bockman et al., 1990). Fertilised soils have shown increases in Cd content after a number of years, but there appears to be little evidence for long-term Cd-increase in crop plants, except possibly for wheat (Jones and Johnston, 1989). Mortvedt (1984) determined the uptake of Cd and Zn by several vegetable crops heavily fertilised with triple superphosphate over a ten year period. Cd levels were found to be similar in fertilised and unfertilised snap bean seed, beet blades and roots, and in sweet corn leaves and grain. However, Zn concentrations were found to decrease with P application in all tissues except cabbage heads and cores. Claims that fertilisers promote the uptake of Al by plants have been refuted (Akerstrand et al., 1988). 

However, the fact that fluorides are (i) associated with the application of some phosphate fertilisers that many leach into surface waters and shallow ground water and (ii) by-product of the phosphate fertiliser industry which are the primary sources of fluoride pollution call upon the need of receptors that are able to interact with both anions. Calix[4]pyrrole and most of the derivatives have... 

The chief varieties of naturally occurring or manufactured phosphatic fertilisers may be classified briefly as follows —... 

Since the phosphorus compounds which are used in the arts, as well as phosphatic fertilisers, are derived from the decomposition of phosphates of lime, and the interactions of these are also of importance in biochemistry, a short account of the best investigated of these compounds will be given here. ... 

Similar natural methods have been adapted to evaluate deposits of cheap rock phosphates as an alternative to expensive, often imported, phosphate fertilisers, and to find the most efficient way to use these fertiliser deposits for maximum plant growth. 

Sarathchandra, S.U., Ghani, A., Yeates, G.W., Burch, G. and Cox, N.R. (2001) Effect of nitrogen and phosphate fertilisers on microbial and nematode diversity in pasture soils. Soil Biology ... 

Sulfuric acid used in the manufacture of phosphate fertilisers, explosives, removal of oxides from metals in storage batteries and in drying towers in chlor-alkali plants... 

These are used for pollution control in phosphatic fertiliser plants where deposits of silica can occur in scrubbing towers. These deposits need to be removed soon. The... 

These are used in phosphatic fertiliser industries where silica/other particulate matter tend to deposit on the walls of the tower. Polypropylene and HOPE can be considered as MOC. The pipes and valves shall be pressure tested before installation. 

The production of ammonium phosphate fertilisers is an example of acidic and alkali media neutralisation under commercial plant conditions [1]. During the production of ammonium phosphate, at the liquid ammonium and phosphoric acid reaction stage, a six-section tubular turbulent reactor of diffuser-confusor design is used. The reactor maintains turbulence along its length, with a reactor diameter of 220 mm and confusor diameter of 105 mm the reactor operates in a normal mode at a... 

Ammonium phosphate fertilisers at the stage of interaction of liquid ammonia with phosphorous acid. 

Before the introduction of phosphate fertilisers, there were few soils in the world which were capable of supplying sufficient phosphate for a sequence of good crop yields. There are, however, still extensive areas of P-deficient soils, particularly in tropical and sub-tropical areas. 

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