Soils organic

Heavy metals, toxic organics and other pollntants have often freqnently been added to wetlands both accidentally and on pnrpose, exploiting their buffering and storage capacities. The chemistry of snbmerged soils and sediments is such that pollutants may be effectively removed from the percolating water in redox, sorption and precipitation reactions. But the effects of long-term accumulation of pollutants on nutrient cycles and other wetland functions are not well understood. 

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A U.S. EPA study (41) showed that soil vapor extraction (SVE) is an effective treatment for removing volatile contaminants from the vadose zone. Sandy soils are more effectively treated than clay or soils with higher organic content because higher air flows are possible in sand and clays—organic soils tend to adsorb or retain more contaminants. Removal of volatiles is rapid in the initial phase of treatment and thereafter decreases rapidly thereafter-an important consideration in the design of air emissions control over the life of the project. 

Dead vegetation also afreets the global carbon cycle. Dead organic matter decomposes, releasing carbon dioxide to the atmosphere. Rates of decomposition vary with material, location, and climate. Non-woody organic matter decomposes rapidly woody organic matter slowly. Decomposition tends to occur faster at the soil surface than below. Decomposition is relatively fast in warm moist climates. In cold climates and in wetlands, decomposition is so slow that there is a net increase of stored carbon in the soil and organic soils called, "histosols, are formed. 

Histosols All organic soil Wetlands, riparian areas... 

Chapman, R.A. and Harris, C.R. (1981). Persistence of pyrethroid insecticides in a mineral and an organic soil. Journal of Environmental Science and Health B 16, (5) 605-615. 

Most research on the rhizospherc environment has been forcedly descriptive in the past. Recent advances show that organic compounds present in the rhizo-sphere can have a specific role in plant-micro-organism-soil interactions. Moreover, it starts to be elucidated ... 

I. Kraffczyk, G. Trolldenier, and H. Beringer, Soluble root exudates of maize influence of potassium supply and rhizosphere organisms. Soil Biol. Biochem. 76 315 (1984). 

D. B. Knaebel, T. W. Federle, D. C. McAvoy, and J. R. Vestal, Effect of mineral and organic soil constituents on microbial mineralisation of organic compttunds in a natural soil. Applied and Environmental Microbiology 60 4500 (1994). 

Figures for the numbers of organic dairy cows in Europe (Foster Lampkin, 1999) indicated that in 1996 Great Britain still had only 3436 organic dairy cows, compared to Austria (87 068), Switzerland (32 504) and Denmark (21417). By 1999 Padel, et al. (2000) calculated that there were 45 million litres of organic milk produced in the UK. From 2000 to 2003 organic milk production in the UK increased by approximately 600%, and the total organic milk collected in 2003 was 293.4 million litres, of which 62% was sold as organic (Soil Association, 2003).

Normally, clay in soil is not present as individual particles but is clustered to aggregates that consist wholly of clay or of a mixture of clay and other mineral and/or organic soil material. Mass transport of soil material along cracks and pores, common in cracking soils in regions with alternating wet and dry periods, does not necessarily enrich the subsoil horizons with clay. 

Organic soils 1 km from smelter vs. reference site 600-6455 VS. 29 21... 

Frank, R., K. I Stonefield, and P. Suda. 1982. Impact of nickel contamination on the production of vegetables on an organic soil, Ontario, Canada, 1980-1981. Set. Total Environ. 29 41-65. 

Application methods Usually as water spray or in liquid fertilizers applied preemergence, but also may be applied preplant or postemergence. Rates of 2-4 pounds/acre (2.24-4.48 kg/ha) are effective for most situations higher rates are used for nonselective weed control, and on high organic soils... 

Mathur, S.P., H.A. Hamilton, and T.C. Vrain. 1980. Influence of some field-applied nematicides on microflora and mineral nutrients in an organic soil. Jour. Environ. Sci. Health B 15 61-76. 

Miles, J.R.W., C.R. Harris, and C.M. Tu. 1983. Influence of temperature on the persistence of chlorpyrifos and chlorfenvinphos in sterile and natural mineral and organic soils. Jour Environ. Sci. Health B 18 705-712. 

Chapman, R.A., C.M. Tu, C.R. Harris, and C. Cole. 1981. Persistence of five pyrethroid insecticides in sterile and natural, mineral and organic soil. Bull. Environ. Contam. Toxicol. 26 513-519. 

Recent studies examining the distribution of smelter-derived elements around a copper smelter found that arsenic deposition rates in snow and concentrations in organic soils decrease gradually with distance from the smelter (Henderson et al. 2002 Knight Henderson 2006 Telmer et al. 2003 Zdanowicz etal. 2006). In order to explore the nature and behaviour of arsenic, a limited number of samples (stack and impacted soil) were characterized. 

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