Organic matter content

The amount of herbicide sorbed by a given soil is influenced by properties of both the soil and the herbicide. Important properties related to the soil s retention abiHty include clay mineralogy, organic matter content, soil pH, and iron and aluminum oxide content. These properties, in turn, affect the... 

Acid amide herbicides are nonionic and moderately retained by soils. The sorption of several acid amide herbicides has been investigated (369). Acetochlor [34256-82-1] is sorbed more than either alachlor or metolachlor, which are similarly sorbed by a variety of soils. Sorption of all the herbicides is well correlated to soil organic matter content. In a field lysimeter study, metolachlor has been found to be more mobile and persistent than alachlor (370) diphenamid [957-51-7] and napropamide [15299-99-2] have been found to be more readily leached (356). 

Nitric oxide and NjO are direct intermediates in the denitrification pathway, the reduction of NO3 to Nj. Reduction to Nj is often incomplete, so that both NjO and Nj are equally important end products of denitrification, the ratio of NjO/Nj production being determined by soil physical properties. For example, NjO is the main end-product in acid soils, whereas low redox potentials and high organic matter content favour the further reduction to Nitric... 

Interrelated with change in particle size and changes in type and kind of soil minerals present, organic matter is formed and accumulates as an integral part of the soil. Organic-matter content varies from practically none in sands to almost 100%, as exemplified by peat formations. The amount of organic matter present thus reflects the interaction of all environmental... 

Methyl parathion is only slightly soluble in pH 7 water (55-60 ppm). This affects its mobility in water and its ability to be leached or solubilized into the water phase of a soil-water system. Factors most likely to affect the adsorption of methyl parathion in soil are organic matter content and cation exchange capacity. In soils of low organic matter (e.g., subsurface soils), calcium concentration, which affects the hardness of the water, may also be important (Reddy and Gambrell 1987). Several studies have shown... 

It has been shown that N-nitrosation was enhanced by the increase in organic matter content of the soil (13). It was postulated that a simple constituent of soil organic matter may be involved as a catalyst. For example, thiocyanate has been... 

The persistence of the N-nitrosamine that may be formed in soil will depend on a host of conditions, such as soil type, organic matter content, clay content, pH, the microflora present in the soil, moisture content and temperature, etc. Superimposed on all these factors will be the chemical nature of the pesticide. The N-nitrosoatrazine ( ) formed in soil from the herbicide atrazine ( ) was shown to be rapidly disappeared (1). Thus, in soil W-nitrosoatrazine was observed after one week, but was absent 4 and 10 weeks later (Table IV). In contrast, N-nitroso-butralin (11 ) persisted much longer than N-nitrosoatrazine (9) under the same conditions (Table V) and was still detectable after 6 months (3). Our studies demonstrated that N-nitrosoglyphosate is persistent in the soil. Fox soil treated with 20 ppm of nitrite nitrogen and 740 ppm glyphosate contained about 7 ppm of N-nitrosoglyphosate even after 140 days (6). 

Greer LE, DR Shelton (1992) Effect of inoculant strain and organic matter content on kinetics of 2,4-dichlorophenoxyacetic acid degradation in soil. Appl Environ Microbiol 58 1459-1465. 

A multi-residue method based on SPE cleanup and gas chromatography/ion trap mass spectrometry (GC/ITMS) was developed for the determination of 120 pesticides and related metabolites in two soils with organic matter contents of 4.0-5.2%. 

Texture, organic matter content, oxygen status and pH values of soil in use area(s) Amqlmts and timing of precipitation Temperature and solar irradiance in use area(s) (temperate vs. tropical vs. nordic)... 

As far as grass growth is concerned, the most important source of water is that available to the roots, and this is known as the available water capacity (AWC). The remainder is unavailable and while this is highest in heavy clays and clay loams, these soils also have the highest AWC. The AWC of soils is improved by an increase in their organic matter content, which improves the soil s capacity to absorb and hold water and also benefits soil structure. 

More actinomycetous isolates were obtained from soils with a high organic matter content than from sandy soils with low organic matter (Table I). Sample I, collected under black locust trees, and sample P, collected under fescue sod in a young apple orchard, yielded the most isolates. Fewest isolates were obtained from sample A, which contained little organic matter due to having previously been burned, and samples C, H, and U, all sandy soils with low organic matter content. 

Much work has been carried out recently on the velocity of detoxication of 2,4-dichlorophenoxyacetic acid under a variety of soil conditions—e.g., high soil moisture content, high temperatures, high pH, and high organic matter content (10,12,15,21, 26). 

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... 

The remaining processes, although they occur under near-surface and deep-well conditions, are less applicable to the latter. Distinct differences between the two environments, however, can lead to significant differences in how the processes affect a specific hazardous substance. Compared with the near-surface environment, the deep-well environment is characterized by higher temperatures, pressures, and salinity, and lower organic matter content and Eh (oxidation-reduction potential). 

Adsorption-desorption Partly Mechanisms for adsorption on similar materials will be similar. Soil adsorption data generally do not reflect the saturated conditions of the deep-well environment. Organic-matter content is a major factor affecting adsorption in the near-surface its significance in the deep-well environment is less clear. Fate studies involving artificial recharge are probably useful, but differences between fresh waters and deep brines may reduce relevance. 

In Prairie silty clay loam (Figure 4), the mobility of all three herbicides was greatly reduced due to the soils high organic matter content (8.2%). Most of the applied radioactivity was found in the upper 10 cm of the column for each compound. 

The organic matter content of muck soil in Florida is about 80%.)... 

Heavy metal) Zinc Lebano Soil - Soil pH - Organic matter content - Lithology - Surroundings of waste areas - Proximity to roads - Distance to drainage line - Slope length [48]... 

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