Agricultural soils

Eand Capability Classification, Agricultural Handbook 210, U.S. Department of Agriculture, Soil Conservation Service, Washiagton, D.C., 1966, 21 pp. 

Environmental Levels and Exposures. Barium constitutes about 0.04% of the earth s cmst (47). Agricultural soils contain Ba " in the range of several micrograms per gram. The Environmental Protection Agency, under the Safe Drinking Water Act, has set a limit for barium of 1 mg/L for municipal waters in the United States. 

About 23 million metric tons of gypsum are consumed aimuaHy. About 80% is processed into the commercially usable hemihydrate. Uses of gypsum are ia fabricated and/or formulated building materials (see Building materials, survey), Pordand cement (qv) set regulation, and agricultural soil conditioning. 

By-Products. The biomass from the fungal fermentation process is called mycellium and can be used as a supplement for animal feed since it contains digestable nutrients (25,26). The lime-sulfuric purification and recovery process results in large quantities of calcium sulfate cake, which is usually disposed of into a landfill but can find limited use in making plaster, cement, waUboard, or as an agricultural soil conditioner. The Hquid extraction purification and recovery process has the advantage of Htde soHd by-products. 

Figure 7 The production and emission of NO during denitrification in agricultural soil treated with NO3 fertilizer (KNO3) and the nitrification inhibitor Dyciandiamide (10%) under aerobic (air) and anerobic conditions (N,). Fluxes are means from three soil columns, error bars represent standard deviations from the mean. V = vertical flow through the column H = Horizontal flow over the soil surface.

F or NjO, estimates of soil emissions are perhaps slightly more straightforward, simply because so much more information on soil NjO emissions is available. For agricultural soils, estimates as a percentage of fertilizer input have been published " and, for the remaining land use classes listed in Table 5, mean annual emissions from a series of long-term flux measurements are available. The total annual soil NjO emissions for the ElK (27 kt N) are very similar to the annual soil NO emissions. Soils, however, have by far a greater impact on the... 

Agriculture Soil stabilization microencapsulation of mineral fertilizers, fungicides, and herbicides... 

The term fuel saving needs to be qualified, since the use of the heat in the water will be given to a process which may be unrelated to boiler demand. Examples of suitable applications occur in laundries, agricultural soil heating, food industries, abattoirs and swimming pool heating. 

Lichtenstein EP, Katan J, Anderegg BN. 1977. Binding of "persistent" and "nonpersistent" 14C-labelled insecticides in an agricultural soil. J Agric Food Chem 25 43-47. 

Regarding soils, a central issue is the persistence and movement of pesticides that are widely used in agriculture. Many different insecticides, fungicides, herbicides, and molluscicides are applied to agricultural soils, and there is concern not only about effects that they may have on nontarget species residing in soil, but also on the possibility of the chemicals finding their way into adjacent water courses. 

Although the major concern about the fate of organic pollntants in soil has been about pesticides in agricultural soils, other scenarios are also important. The disposal of wastes on land (e.g., at landfill sites) has raised questions about movement of pollutants contained in them into the air or neighboring rivers or water conrses. The presence of polychlorinated biphenyls (PCBs) or PAHs in snch wastes can be a significant source of pollution. Likewise, the disposal of some industrial wastes in landfill sites (e.g., by the chemical industry) raises questions about movement into air or water and needs to be carefully controlled and monitored. 

Chlorinated anilines are produced by the hydrolysis of a range of acetanilide, urea, and carbamate herbicides, and are therefore widely distributed in agricultural soils. Mechanisms for their loss... 

The pathway for the degradation of metribuzin that has been used as a herbicide has been established, and attention has been directed to the occurrence of the metabolites in leachate from agricultural soil in Denmark. Although the parent metribuzin was not found, the metabolites produced by loss of the N-amino group and the thiomethyl groups were produced and contributed to ground-water contamination (Kjaer et al. 2005). 

Bouwman, A. F. (1996). Direct emission of nitrous oxide from agricultural soils. Nutr. Cycl. Agroecosyst. 46, 53-70. 

M. Hungria, and G. Stacey, Molecular signals exchanged between plants and rhizo-bia basic aspects and potential application in agriculture. Soil Biol. Biochem. 29 819 (1997). 

S. Tagaki, Mechanism of iron uptake regulation in roots and genetic differences. Agriculture, Soil Science and Plant Nutrition in the Northern Part of Japan. (Japanese Society of Soil Science and Plant Nutrition eds.), 1984, Tokyo, Japan, p. 190. 

D. S. Powlson, Measuring and minimising losses of fertilizer nitrogen in arable agriculture. Nitrogen Efficiency in Agricultural Soil. (D. S. Jenkinson and K. A. Smith, eds.), Elsevier, Oxford, 1988, p. 231. 

S. L. Jansson and J. Persson, Mineralization and immobilization of soil nitrogen. Nitrogen in Agricultural Soils, Vol. 22 (F. J. Stevenson, ed.), American Society of Agronomy, Madison, 1982, p. 229. 

P. Nielsen and J. Sorensen, Significance of microbial urea turnover in N cycling of three Danish agricultural soils. FEMS Microh. Ecol. 25 147 (1997). 

S. Jen.sen, L. Ovreas, F. L. Daae, and V. Torsvik, Diversity in methane enrichments from agricultural soil revealed by DGGE separation of PCR amplified 16S rDNA fragments. FEMS Microbiol. Ecol. 26 17 (1998). 

Accumulation of cadmium in agricultural soils leads to increased cadmium uptake by crops and vegetables, grown for human consumption.17... 

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