Fertilizers in soils

Calcium phosphate precipitation may also be involved in the fixation of phosphate fertilizer in soils. Studies of the uptake of phosphate on calcium carbonate surfaces at low phosphate concentrations typical of those in soils, reveal that the threshold concentration for the precipitation of the calcium phosphate phases from solution is considerably increased in the pH range 8.5 -9.0 (3). It was concluded that the presence of carbonate ion from the calcite inhibits the nucleation of calcium phosphate phases under these conditions. A recent study of the seeded crystal growth of calcite from metastable supersaturated solutions of calcium carbonate, has shown that the presence of orthophosphate ion at a concentration as low as 10-6 mol L" and a pH of 8.5 has a remarkable inhibiting influence on the rate of crystallization (4). A seeded growth study of the influence of carbonate on hydroxyapatite crystallization has also shown an appreciable inhibiting influence of carbonate ion.(5). 

Fitzpatrick R. W., McKenzie, N. J., and Maschmedt, D. (1999). Soil morphological indicators and their importance to soil fertility, in Soil Analysis an Interpretation Manual (K. Peverell, L. A. Sparrow, and D. J. Reuter, Eds.). Melbourne, Australia CSIRO Publishing, 55-69. 

Mulder, E.G., Lie, T.A. and Woldendorp, J.W., 1969. Biology and Soil Fertility in Soil Biology. Reviews of Research, UNESCO Natural Resources Research IX, Paris. 

In soils, the prevalence and importance of solid solution formation in controlling cation and anion solubility has not yet been determined. Certain minerals readily incorporate only those metal ions with radii similar to the radius of the structural metal ion. For calcite, this means that Mn, Cd , and Fe readily enter the calcite structure on precipitation while smaller ions such as Cu " and Zn do not. Even so, it is not clear that metal selectivity demonstrated by pure solid solutions has much control in soils and sediments. A case in point is the lack of evidence for a strong association of Cd and Pb " with calcite in natural sediments, despite the favorable radii of these metals compared with Ca ". On the other hand, both Cd and Pb " are associated with hydroxyapatite in nature because they fit well into the Ca " site of this mineral. This association poses a problem for the long-term use of phosphate fertilizers in soils. 

Avetyam, R.M., LG. Mokhnachev, D.N. Latayeva, and L.F. Maksimova Effect of mineral fertilizers in soils with varying moisture supply on the volatile phenols in tobacco smoke Biol. Arm. 21 (1968) 78-83, see Chem. Abstr. 70 (1969) 17626. 

What is a major advantage of using anhydrous ammonia as a source of nitrogen fertilizer in soil What role is played by bacteria that enables anhydrous ammonia to be an effective plant fertilizer ... 

BIEDERBECK V.O. 1978. Soil Organic Sulphur and Fertility. In Soil Organic Matter. Eds. Schnitzer M. and Khan S.U. Elsevier Press, New York. 

In addition to a continued increase in the number of use patents in these fields, a new use of xanthates as inhibitors of fertiliser nitrogen transformation in soil has been reported, as well as the use of certain metal xanthates as color developers for image-recording materials (113,114) (see Fertilizers Color photography). For several years, sodium isopropyl xanthate was used as an intermediate in the manufacture of saccharin (see... 

ABOUT EXTRACTION AND STABILITY OF HEXAVALENT CHROMIUM IN SOILS AND FERTILIZERS... 

Nitrate is one of the facts of life. It is essential for the growth of many plant species, including most of those we eat, but it becomes a problem if it gets into water in which it is not wanted. It is perceived mainly as a chemical fertilizer used by farmers, but much of the nitrate found in soil is produced by the microbes that break down plant residues and other nitrogen-containing residues in the soil. There is no difference between nitrate from fertilizer and that produced by microbes, but, whatever its origin, this rather commonplace chemical entity has now become a major environmental problem and is also treated as a health hazard. 

The best overall recovery of labelled fertilizer in crop and soil was 99% and the leastsatisfactory 65%. Thus 1-35% ofthe labelled nitrogen, onaverage 15.7%, was missing, presumed lost . These losses occurred between the time of the fertilizer application in spring and the time the crop was harvested but why and how did they occur ... 

Percentage of labelled fertilizer nitrogen left in soil at harvest, and percentage increase in soil mineral nitrogen at harvest caused by fertilizer ... 

Cases (e), (g), and (h) are of interest in the cathodic protection of warm objects (e.g., district heating schemes [89] and high-pressure gas lines downstream from compressor stations [82]) because the media of concern can arise as products of cathodic polarization. The use of cathodic protection can be limited according to the temperature and the level of the mechanical stressing. The media in cases (a) and (f) are constituents of fertilizer salts in soil. Cathodic protection for group I is very effective [80]. 

An expanded mica (hydrated magnesium-aluminium-iron silicate). Used in lightweight aggregates, insulation, fertilizer and soil conditioners, as a filler in rubber and paints, and as a catalyst carrier. 

Sludge cake from vacuum filters, because of its pasty nature, cannot be readily spread on land as a fertilizer or soil conditioner. It must be further air-dried. At some plants the sludge cake is stockpiled on the plant site over winter. Freezing, thawing and air drying result in a material which breaks up readily. 

Meints, V.W., Boone, L.V and Kurtz, L.T. 1975 Natural N abundance in soil, leaves, and grain as influenced by long term additions of fertilizer N at several rates. Journal of Environmental Quality 4 486 90. 

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