FIELD APPARATUS FOR KNIFE INJECTION OF NITROGEN-15-LABELED LIQUID ANHYDROUS AMMONIA

Liquid anhydrous ammonia (LAA) fertilizer is applied in a band under field conditions. Applications of N-15-labeled LAA presents unique difficulties because greater precision and flow control of small quantities of LAA are necessary than are possible with conventional field equipment. Previous procedures for field applications of N-15-labeled LAA have nevertheless at least required the assistance of conventional field equipment. An apparatus is described that allows precise mechanical application of N-15-labeled LAA to field soil without conventional-sized equipment. The LAA is dispensed with a conventionally styled applicator knife pulled by an electrical winch along a stationary track. N rate adjustment is made with a calibrated metering valve. Application can be made for various plot lengths and soil depths, and may include nitrification inhibitors. Precision of application is comparable to a previously published apparatus (CVs of 3% or less) for a three-band plot.