Organic residue decomposition products

Neutral interactions are found extensively in the rhizosphere of all crop plants. Saprophytic microorganisms are responsible for many vital soil processes, such as decomposition of organic residues in soil and associated soil nutrient mineralization/turnover processes. While these organisms do not appear to benefit or harm the plant directly (hence the tenn neutral), their presence is obviously vital for soil nutrient dynamics and their ab.sence would clearly influence plant health and productivity. 

Because the results obtained reflect the presence, not only of the insecticide in question, but also of any of its decomposition products or other organic compounds containing halogen, confirmatory evidence of the identity and amount of the residues was desired, Therefore, studies to correlate the results of organic-chlorine determinations with insecticidal activity were undertaken. 

There are numerous reports describing the allelopathic (phytotmicrobial products on crop growth, particularly in conjunction with heavy residues from the previous crop (1-5). The cause of the reduced crop growth has been attributed to the production of a variety of toxic compounds such as phenolic acids, short-chain fatty acids, patulin, and many others (6-9). These compounds may be produced directly or indirectly during the microbial decomposition of organic residues under varying environmental conditions, such as when the soil remains wet over an extended period of time. 

An assessment of the rates and duration of phenolic acid production from a residue is an important first step. Laboratory and field studies for assessing the dynamics of phenolic acid production must include considerations of the nature of the residue, soil properties, nutrient status of the system, microbial biomass interrelationships, temperature, moisture, residue placement in or on the soil, and other factors that relate to the field. Soil properties in the field are especially important when organic residues are incorporated. When soils are wet, such as those with more than -0.02 MPa water potential, oxygen diffusion is impeded and anaerobic conditions prevail, especially in soils that are high in clay content. Under these circumstances, microbial byproducts change dramatically and one result, for example, is an increase in the production of phenolic acids. Phenolic acid production is also affected by temperature (22) and soil fertility status (23). While the C H ratio of an organic residue may influence the rate of its decomposition and, hence, the rate of phenolic acid production, the... 

These definitions were essentially the same as those put forward by Berzelius. Mulder considered, however, that, besides humus substances, products from the decomposition of organic residues, such as leucine, butyric acid, valeric acid, and formic and ethanoic acids, could exist in soil. These observations are of interest because of the information that has emerged in the past half-century about growth inhibitors and stimulators from low-molecular-weight extracts from SOM and composts. 

Salts giving gaseous decomposition products (e.g., nitrates) do not usually problems. With organic salts a problem may arise because of the possible formation of carbonaceous residues. Sufficient air or oxygen must be supplied to avoid this difficulty. 

In the late 1970s HPLC provided an ideal tool for the analysis of pollutants and other environmental contaminants. Techniques were developed for analyzing chlorophenols, pesticide residues, and metabolites in drinking water and soil (parts per trillion) and trace organics in river water and marine sediments, and for monitoring industrial waste water and polynuclear aromatics in air. Techniques were also developed for determining fungicides and their decomposition products and herbicide metabolites in plants and animals. 

In waters and wastewaters, organic amines and their decomposition products such as ammonia may be present, hi addition, ammonia may be purposely added for chloramine formation to produce chlorine residuals in distribution systems. Also, other organic snbstances snch as organic amides may be present as well. Thus, from point A to B, chloro-organic compounds and organic chloramines are formed. Ammonia will be converted to monochloramine at this range of chlorine dosage. 

All three of the methyl amines are found naturally in herring brine, and in the dry distillation products of the residues obtained from fermented beet sugar molasses after it has been evaporated to drive off the alcohol and water. They also occur in certain plants and as the decomposition products of more complex nitrogenous organic substances such as morphine. 

Organic peroxides and peroxodisulfates as well as some azo compounds and carbon-carbon compounds are mainly used as initiators in radical polymerization. The production volume of these initiators exceeds 250,000 metric tons. More than 50% of all polymers are made industrially by radical polymerization. Considering that the annual worldwide production of polymers is in the range of 200 Mio metric tons, it indicates that initiators have fundamental importance. The quantity of initiator used varies in a range from 0.01- 5% depending on the process and polymer applied (Fig. 1). Their decomposition products become incorporated or remain as a residue in this large volume of polymers (Fig. 2). 

These considerations lead to the conclusion that to a first approximation the quantity and quality (with respect to sulfate reducers) of organic matter at each of the three stations is nearly the same. The rate of supply of organic material also cannot differ much if it is assumed that a constant proportion of the flux of organics hitting the interface at each station must remain as refractory residue and therefore is reflected in the standing crop. Taken at face value, these data indicate that FOAM, which has the greatest buildup of decomposition products in the pore water, is not necessarily the most productive of the three stations. Additional evidence for relative reaction rates at the three stations comes from solid-phase properties as discussed subsequently. 

The oxidation of ethylene oxide on silver yields carbon dioxide and water, but the amounts of these are not equivalent to C2H40 consumption. Twigg believes that this is accounted for by an adsorbed organic residue formed on the catalyst surface. Ethylene also detected in oxidation products was thought to be formed by ethylene oxide decomposition to ethylene and adsorbed oxygen. 

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