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Soil bulk density and cone index were measured just above a hardpan beneath the centerlines of tires representative of front and rear tires of a mechanical front wheel drive (MFWD) tractor with dual rear tires. A 14.9R30 R-1 front tire and an 18.4R42 R-1 rear tire were operated on a sandy loam and a clay loam soil with loose soil above hardpans in soil bins, using three combinations of dynamic load and inflation pressure representative of a tractor hitched to a row-crop planter. When the tractor is used with either an integral planter with liquid chemical carried on the tractor, or a towed planter without liquid chemical carried on the tractor, the front tires are the major source of soil compaction caused by tractor tires. A tractor configured for use with a towed planter without liquid chemical carried on the tractor causes less soil compaction beneath the tractor tires than a tractor configured for an integral planter with liquid chemical carried on the tractor.

Two peristaltic pumps were tested to determine their accuracies in metering three liquid herbicides for injection-type sprayers. To maintain acceptable chemical application accuracy from either pump, recalibration is necessary if the formulation or its temperature changes. An experimental thermal flowmeter was developed and evaluated along with turbine and piston flowmeters. The piston flowmeter had the best linearity and smallest time constant. A system to control the flow rate of the injected chemical is proposed and was simulated to determine its dynamic response. The proposed chemical metering system, coupled with plumbing systems of sprayers used by private and commercial applicators, were simulated to predict chemical application accuracies.