The present invention is directed to a method which enables the user to select a suitable soya variety as a subsequent crop to maize when weed control in that maize crop has been carried out using HPPD inhibitor herbicides in a manner that \u201ccarry-over\u201d damage to the soya crop is thereby avoided. The defoaming substance includes a defoaming agent and a carrier material intermixed with the defoaming agent to form a solid mass, the carrier material being at least minimally soluble in the aqueous solution. Each filter segment functions over a specific range of wavelengths, where the center-to-center wavelength difference between adjacent segments and the wavelength bandwidth of each segment are defined in large part by the chirp in the grating. At least one protrusion adjacent the abutment portion defines a recess for receiving the first end of the first shank during setting of the rivet. The system also includes a cover coupled to opposite sides of the carriage so that the cover extends away from the carriage and continuously between the opposite sides of the carriage.