Surface soil preparation

Plot maintenance B Expertise must be available to maintain the test site and, if cropped, to take care of the crop For bare-soil studies, the soil surface must be carefully prepared prior to test substance application and kept weed-free without disturbing the test areas. If the test is cropped, the crop should be treated according to Good Agricultural Practice. In case of a soil accumulation study, the field may be cultivated and cropped each season for up to 6 years... 

In addition to being smooth, it is preferable that the soil surface be firmly packed. This is because loose soil is not always retained in large-diameter sampling probes. Firming of the soil surface may be accomplished using a turf roller or equivalent. Alternatively, the soil surface may be prepared in advance of study initiation to allow rainfall or irrigation to settle and firm the soil. This latter approach also allows soil surface depressions to be observed and avoided when laying out the test plots. 

Assuming proper soil surface preparation (i.e., smooth with no soil clods or crop debris) and test substance application, the diameter of the soil probe does not generally impact observed pesticide residue concentrations in soil or associated variability. Nevertheless, a minimum diameter of 5 cm for the upper soil probe is recommended to improve sampling under less than ideal conditions. Increasingly, researchers are using probes having diameters >5 cm with good results under a variety of field conditions. 

Methods for Determining Parent Compounds and Degradation Products in Environmental Media. Human exposure to diazinon occurs via inhalation of ambient air ingestion of contaminated food and water and dermal uptake through occupational and non-occupational contact with contaminated soils, surface water, and commercial preparations. Methods have been reported for the measurement of... 

Rodgers et al. [85] identified soil surface-bound polycyclic aromatic hydrocarbons through the use of real-time aerosol mass spectrometry in two NIST standard research material soils (Montana SRM 2710 and Peruvian SRM 4355), each contaminated separately with three common petroleum hydrocarbons (diesel fuel, gasoline and kerosene). This method required no sample preparation. Direct laser desorption/ionisation mass spectrometric analysis of individual soil particles contaminated with each of the petroleum hydrocarbons at three different contamination levels (0.8,8, and 80 ppth (wt/wt)) yielded detectable polycyclic aromatic hydrocarbon cation distributions that ranged from m/z 128 to 234, depending on the fuel contaminant. The same analysis... 

Urethane may be released to the environment in various waste streams from its production and use in the preparation and modification of amino resins, as a solubilizer and cosolvent for pesticides and fumigants, as an intermediate in the production of pharmaceuticals, as an antineoplastic agent, and as a reagent in biochemical research. If released to the atmosphere, urethane is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase urethane will be degraded in the atmosphere by reaction with photochemically produced hydroxyl radicals with an estimated half-life of 2.2 days. If released to soil, urethane is expected to have very high mobility. Volatilization from moist soil surfaces is not expected to occur. Biodegradation of urethane in soil may be important. If released into water, urethane is not expected to adsorb to suspended solids and sediment in the water column. Volatilization from water surfaces is not expected. The potential for bioconcentration in aquatic organisms is... 

Stubble-mulch farming is commonly defined (McCalla and Army, 1961 Horning and Oveson, 1962) as a year-round way of managing plant residues on cropland in which harvesting, cultivating, seedbed preparation, and planting are performed in such a way as to leave the residues of the previous crop on top of or near the soil surface. 

The soil surface should be prepared so that following drilling it will be as level as possible to prevent problems when machine harvesting. 

A form of rainwater harvesting involves collection on the soil surface. Soil can be prepared especially for this purpose, such as by planting grass varieties that produce a dense sod from which rainwater tends to wash off. Large parking lots and other paved areas are potential sources of rainwater runoff that can be harvested. 

A site survey will be carried out, from which a number of parameters can be established, e.g. carrying capacity of the soil at the planned location, possible access routes, surface restrictions like built-up areas, lakes, nature reserves, the general topography, possible water supplies. The survey will allow the adequate preparation of the future location. For instance, onshore in a swamp area the soil needs to be covered with support mats. 

The preparation of soils for crops, planting, and tilling raises dust as a fugitive emission. Such operations are shll exempt from air pollution regulations in most parts of the world. The application of fertilizers, pesticides, and herbicides is also exempt from air pollution regulations, but other regulations may cover the drift of these materials or runoff into surface waters. This is particularly true of the materials are hazardous or toxic. 

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