Soil phosphorous

Microbial biomass P Chloroform fumigation extraction Indicate biologically active fraction of soil phosphorous control P cycle dependent upon organic amendments Brookes et al. (1982)... 

Loes, A.K. and Ogaard, A.F. 2001. Long-term changes in extractable soil phosphorous (P) in organic dairy farming systems. Plant and Soil 237 321-332. 

Sedimentation analysis is suitable for a wide variety of materials and is used for both quaHty control and research work, such as agglomeration studies (56), and gives well-defined, relatively high resolution results. The technique has been employed in the evaluation of soils, sediments, pigments, fillers, phosphors, clays (qv), minerals, photographic haHdes, and organic particles (57,58). 

In paints, zinc oxide serves as a mildewstat and acid buffer as well as a pigment. The oxide also is a starting material for many zinc chemicals. The oxide supphes zinc in animal feeds and is a fertilizer supplement used in zinc-deficient soils. Its chemical action in cosmetics (qv) and dmgs is varied and complex but, based upon its fungicidal activity, it promotes wound healing. It is also essential in nutrition. Zinc oxide is used to prepare dental cements in combination with eugenol and phosphoric and poly(acrylic acid)s (48) (see Dental materials). 

Phospha.tes, Pentasodium triphosphate [7758-29-4] sodium tripolyphosphate, STPP, Na P O Q, is the most widely used and most effective builder in heavy-duty fabric washing compositions (see also Phosphoric acid and phosphates). It is a strong sequestrant for calcium and magnesium, with a p c of ca 6, and provides exceUent suspending action for soils. Because of its high sequestration power, it also finds extensive appHcation in automatic-dishwashing detergents. Sodium tripolyphosphate forms stable hydrates and thus aids in the manufacture of crisp spray-dried laundry powders. 

Polyphosphoric acid supported on diatomaceous earth (p. 342) is a petrochemicals catalyst for the polymerization, alkylation, dehydrogenation, and low-temperature isomerization of hydrocarbons. Phosphoric acid is also used in the production of activated carbon (p. 274). In addition to its massive use in the fertilizer industry (p. 524) free phosphoric acid can be used as a stabilizer for clay soils small additions of H3PO4 under moist conditions gradually leach out A1 and Fe from the clay and these form polymeric phosphates which bind the clay particles together. An allied though more refined use is in the setting of dental cements. 

A variety of phosphoric acid triesters and their derivatives are used as pesticides. Although there are no natural phosphorotriesters, those artificial ones undergo decomposition in the soil, implying that some microorganisms exist which are capable of hydrolysing them. The first report on a stereoselective enzymatic phos-photriester hydrolysis was pubhshed in 1973, when Dudman and Zerner succeeded... 

F. J. Stevenson, Cycles of Soil Organic Carbon, Nitrogen, Phosphorous, Sulphur, Micronutrients, J. Wiley Sons, New York, 1986,... 

High organic matter content is typically associated with high microbial numbers and a great diversity of microbial populations. Organic matter serves as a wardrobe of carbon and energy as well as a source of other macronutrients such as nitrogen, phosphorous, and sulfur. Subsurface soils... 

Biotic control over the functioning of soil ecosystems also follows the model described by Chapin et al. (1997) for universal ecosystem. Types of soil biota and their composition are likely to alter soil ecosystem processes through changes in the functional traits (Fig. 10.1). It can alter ecosystem processes, such as phosphorous transformation and availability by plants, which in turn modifies community... 

Parfitt RL, Yeates GW, Ross DJ, Mackay AD, Budding PJ (2005) Relationship between soil biota, nitrogen and phosphorous availability and pasture growth under organic and conventional management. Appl Soil Ecol 28 1-13... 

Along with this were investigations of the elemental content of plants and the relationship between those elements found in soil and those found in plants. As these investigations advanced, it became evident that the inorganic components in soil were essential to plant growth and that crop production could be increased by increasing certain mineral components in soil. It did not take too long to determine that ammonia, phosphorous, and potassium are the three essential components that increase plant productivity. At this early point,... 

Millions of soil samples per year are analyzed for nonpoint source analytes such as potassium, phosphorous, insecticides, and herbicides. It is necessary to obtain an idea of the level of these components throughout the field and to take corrective action as necessary. Thus, a more random sampling methodology is called for. Figure 7.2 shows a field that includes both different soil types (letters) and topographical features (e.g., a ditch) that are to be sampled. Also, a transect line and locations of sample sites along it are indicated. Transect lines and sampling sites are discussed later. 

Caution Chromates, including potassium and sodium dichromate, are hazardous materials, as are sulfuric and phosphoric acid used in the oxidation of soil organic matter. Great care must be exercised in using these chemicals and in disposing of the waste generated. 

Source Reproduced with permission from the American Chemical Society [155] aAdd 3ml IN phosphoric acid to soil sample and leave 15min before solvent extraction... 

---