Treated plots

Results indicated that a one time biosolids treatment ranging from 22.5 to 45 dry Mg/ha (10 to 20 dry ton/ac) yielded positive vegetative response without harm to the environment. An unexpected benefit from the biosolids treatments was a decrease in broom snakeweed, a toxic, non palatable competitive range plant. Following the addition of biosolids, the number of broom snakeweed plants in the biosolids-treated plots decreased over the course of the study. 

Control plots should be placed upslope and upwind of the treated plots. 

Field maintenance must be done first in the control and next in the treated plots. All documents must be entered in the field notebook. 

Pesticide should not be sprayed during strong winds, and especially when wind is blowing towards the control plot from the treated plot. 

Samples must be collected first from the control and then from the treated plots starting with the lowest concentration and finally from those applied at the highest concentration. 

Control samples are collected once on the day of the first sampling of the treated plots in most studies to avoid contamination. 

The slope of the land upon which the field trials will be established and the direction of the prevailing wind must be taken into consideration when locating the treated and untreated plots in a field trial. The protocol may specify a certain separation distance for the plots however, the PI must ensure that the plots are located with adequate separation to prevent contamination of the untreated plot during the course of the trial. The untreated plot must be located up-slope and up-wind from the treated plot to reduce contamination from wind or rain. When the land is level or the wind is not from a reasonably constant direction, then distance may be the only feasible way to ensure that plot integrity is maintained. Careful attention to plot placement in the field and documentation of this location in the field notebook will help minimize questions or concerns about the trial site during preparation of the final report. 

Untreated (control) soil is collected to determine the presence of substances that may interfere with the measurement of target analytes. Control soil is also necessary for analytical recovery determinations made using laboratory-fortified samples. Thus, basic field study design divides the test area into one or more treated plots and an untreated control plot. Unlike the treated plots, the untreated control is typically not replicated but must be sufficiently large to provide soil for characterization, analytical method validation, and quality control. To prevent spray drift on to the control area and other potential forms of contamination, the control area is positioned > 15 m away and upwind of the treated plot, relative to prevailing wind patterns. 

The guiding principles in test plot maintenance are to (1) minimize soil surface disturbance at all times, (2) ensure that control and treated plots are similarly maintained, (3) avoid applying other agrochemicals that may interfere with sample analysis or that are otherwise contrary to the purpose of the study, (4) follow the prescribed irrigation policy determined for the study site, and (5) keep bare-soil test plots free of vegetation, as follows. 

The foliar and soil treated plots and control area will be identified with markers so that the treated plots and control area do not have the same flag or marker colors. 

Once the first spray has been applied, overhead sprinklers must not be used in the treated plot and control area under any circumstances. Irrigate only under plants for non-DSR studies. 

All maintenance pesticide applications must be approved in advance and documented. Pesticides that do not interfere with analysis may be applied in order to control weeds, pathogens, and other pests if they appear in the treated plot and control area only if absolutely necessary. The treated plot and control area should be maintained with the same compound and rate and at the same time. 

Each site should consist of two plots, as a minumum, one treated per formulation and one untreated. The untreated plot should be positioned upslope (if applicable) and upwind (at application) at least 100 ft from the treated plots to reduce the potential for contamination due to drift. All plots should be uniquely... 

This author recommends a minimum plot size of 4 rows x 200 ft for each treated plot. Foliar sampling would occur on the middle two rows with a 10-ft buffer on each end. Soil sampling would occur on each side of the middle two rows with a 10-ft buffer on each end. The 180-ft rows should be divided into 60-ft replicates designated as A, B, and C. The untreated plot should be 2 rows x 50 ft. For tree crops, 3 rows x 14 trees should be treated. The middle row should be sampled excluding the first and last trees. 

The treated plots and control area should be managed according to agricultural practice in the area. Fertilization should be made according to normal agricultural practice and documented as to when and how applied include rate and composition. Soil preparation and other cultural practices must be noted. 

In this study the control plot was located upwind from the treated plot, considering the prevailing wind at the site. The distance between the control plot and the treated plot should be > 1000 ft 100 ft is the recommended minimum. The control plot was 200 X 20 ft and four rows wide with a 10-ft buffer at each end of the sampling plot. 

Sprayers should be calibrated prior to each application. If, at the time of application, the wind is blowing in the direction from the treated plot to the control plot, then wait until the direction changes to prevent contamination of the control plot. Applications should occur within 1 h of mixing. Check weather forecasts to determine if wind or rain could be a problem. Airblast sprayers must be adjusted to spray through the target crop and cover the top of trees. Research sprayers often do not have the power for this job. 

The regulations require three samples from the treated plot (one from each subplot) and a single sample from the control plot at each sampling interval. For foliage the preferred technique is to collect leaf punch samples. Leaf punch samplers are available in 5-, 2.5- and 1.25-cm punch areas. Common practice requires a sample of 40-5-cm leaf disks to provide a 400-cm sample using both the top and bottom of the leaf disk to calculate sample surface area. 

United States Ohio 1987 old-field community treated with sewage sludge for 10 years beginning in 1978 treated plots vs. reference site ... 

Sweet orange, Citrus sinensis-, 4-year-old trees M3 extractable soil copper >60 mg/kg DW (from treated plots containing about 120 kg Cu/ha) Growth adversely affected positive correlation between copper concentrations in feeder roots (4 to 450 mg Cu/kg DW) and M3 extractable soil copper 17... 

Total bird numbers on treated plots decreased. Some of the decrease (2-3%) was due to death, but most represented movements of birds in reaction to a reduction in their arthropod food. Brain cholinesterase levels in several avian species were depressed 1 week posttreatment (Mullie and Keith 1993)... 

Drift and volatilization are important factors for large-scale transport from the treated plots. Whereas the range of drift of pesticide in droplets is limited to adjacent ecosystems, volatilization (i.e., vaporization) may lead to a large-scale aerial transport. The physics of spray drift involves Stake s law for the derivation of sedimentation velocities of droplets. 

These counts (32) clearly show that the treated plots contained far fewer larvae than either those drained for weevil control or the untreated and continuously flooded plots. The cost of the insecticidal treatment is believed to be less than half as much as draining, drying, and reflooding fields. Counts of mosquito larvae in all plots taken 4 days after the drained plots were reflooded showed less than 1% as many mosquitoes in the undrained plots as in those drained and reflooded. Less water was required for continuous flooding than for draining and reflooding. 

Astrom et al. (2007) compared the total coliform and E. coli contamination of surface runoff and tile effluent from two no-till field plots one with surface-applied liquid dairy manure and a nonmanure-treated plot. These researchers found greater bacterial populations in surface and tile waters from the manure treated plot, but significant contamination occurred from the nonmanured plot attributed to bird and other wildlife feces. Soupir et al. (2006) examined the release and transport of bacteria from manure applied to pastureland. Using rainfall simulations, they... 

Table III.--Residues of carbaryl (pg/cm2) found on apple leaves from two treated plots at various intervals after treatment.

The succession of AF as seen by the sequential reproduction of fungi on soil in urea-treated plots roughly follows the following scheme ... 

---