Growing and maintenance of trial site crops

Prior to setting up the trial, site histories should be evaluated to ensure that chemicals applied previously do not influence the outcome of the planned analysis of the residues. Methods of cultivation should be identical for both treated and untreated plots. 

The crop must be maintained in a healthy condition, free from disease and pests during the conduct of the study. To this end, application of crop protection products other than those being tested may be required. These compounds must not interfere with the determination of the residue. These products should be applied to both treated and control plots. 

A record of any irrigation schemes (type of system used and amount of water) used during the conduct of the trial must be recorded. Often, fertilizers and maintenance chemicals may be mixed into and delivered with the irrigation water, and, hence, details must be recorded. In the case of long-term studies such as soil dissipation or accumulation studies, additional information about the water being used for irrigation (pH, major ion constituents, etc.) must be recorded. 

These maintenance applications are often made by the farmer/cooperator, and these need to be documented. Often a contract can be drawn up with the grower, explaining carefully to him or his technical advisor what the objectives of the study are at the start so that no contamination occurs as a result of maintenance applications by the grower. 

The use of small plot trial equipment specifically designed for trials work usually has an advantage over commercial equipment when calibrations must be performed. 

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