Correct nitrogen (N) management is essential for sustainable corn (Zea mays L.) production. While N fertilizer is an expensive input, this nutrient is critical since corn is in general very responsive to N fertilization. Proper N management is important not only in terms of profitability but also environmental protection. Anhydrous ammonia (NH3) is an important source of N fertilizer in much of the US Corn Belt, with some states applying close to fifty percent of their N in this form. This source of N is injected in the soil during fertilization to reduce losses to the atmosphere. Nitrogen losses to the atmosphere have negative effects to the environment and represent a lost input to the farmer. For these reasons, there have been many studies conducted to determine the appropriate depth, speed, and soil conditions to minimize losses (Jackson and Change, 1947; Stanley and Smith, 1956; Baker et al., 1959; Wagner and Smith, 1958; Abo-Abda, 1985). There is growing pressure to move N application from fall to spring and sidedress times to try to reduce the potential of N loss. This pressure (which also shrinks time of application to a smaller time-frame) comes at a period when farm size is increasing, the use of no-till or other tillage systems with minimal crop-residue disturbance is desired for soil conservation purposes, and reduction in fuel consumption is important to reduce production costs and carbon emissions. All these factors makes it necessary to investigate the possibility of applying anhydrous ammonia with equipment that allows faster application, lower fuel consumption, and minimal disturbance of the soil. Applications at shallow depths, as long as ammonia losses are maintained at an acceptable low level, may be a possible way to achieve these desired outcomes. Recently, a high speed low draft (HSLD) applicator, most commonly known as John Deere 2510H, was developed to inject anhydrous ammonia at shallow depth with minimal soil disturbance. Our objectives were to: compare a prototype of the HSLD injection system to a John Deere conventional till knife (TRAD) applicator; to compare corn plant stand, growth, and grain yield response to the two application systems; and to evaluate the impact of ammonia application method, timing, and rate on plant N status and grain yield.
Soil Science Extension
University of Wisconsin Madison