Corn Yield Response to Nitrogen at Multiple In‐Field Locations

Abstract

Improving N management for corn (Zea mays L.) production with precision agriculture technologies requires that spatial N recommendations adequately represent in‐field variability in N availability. Our objective was to evaluate corn response to increasing N rates in several in‐field locations that represented the range of soil organic matter (OM) content in the field. In a 2‐yr study, three center pivot–irrigated fields were selected in south‐central Kansas and south‐central Nebraska. Four or five locations were selected within each field. At each location, five or six N treatments (0–336 kg N ha−1) were surface‐applied early in the growing season. The minimum N rate to achieve maximum yield varied by as much as 130 kg N ha−1 among in‐field locations at three site‐years. The least amount of N to achieve maximum yield did not coincide with locations representing greater soil OM. Yield response at two site‐years was the same among in‐field locations; however, mean yield among in‐field locations varied by as much as 4.2 Mg ha−1, representing potential for improvement in N use efficiency. Leaf tissue N was below the critical threshold for 60 to 100% of observations at three different in‐field locations but below the critical threshold for <35% of the observations at all other in‐field locations. The reason for the discrepancy in N availability among in‐field locations was not conclusively identified but was not only related to soil OM content. Variable N recommendations based only on soil OM is too simplistic to reflect variability in N availability within a field.

Strategies for improving nitrogen use efficiency: A review

“…At Australia, from large scale demonstration it has been reported that recovery efficiency was 37% for broadcasting and 49% for deep placement of USG in rice; hence deep placement of N fertilizers can improve nitrogen recovery (Balasubramanian et al, 2002). Placement of urea with mud balls technique in the reduced zone of transplanted puddled rice field also improves N recovery and gave better crop output (Schmidt et al, 2002). Further, foliar feeding of nitrogen either through urea spray, can also improve NUE as it reduce different losses i.e.…”

“…Some genotypes may produce different grain yields with the same amount of N uptake. Differences in the efficiency of N acquisition may arise from (1) differences in the efficiency of absorption and assimilation of NH 4 + and other N species and their regulation (Schmidt et al, 2002); (2) the extent and distribution of roots, age of roots, and root induced changes in the rhizosphere affecting N mineralization, transformation, and transport ; and (3) root associated biological N fixation (Shrestha and Ladha 1996). While, differences in the efficiency of internal N use (PE N ) may arise from differences in (1) internal N requirements for growth, (2) ability to translocation, distribute and mobilize absorbed N to and from various organs, (3) flag leaf N import-export and leaf senescence patterns, and (4) the efficiency of converting CO 2 into carbohydrate .…”

“…Remote or local N sensors can be used in sophisticated management approaches to assess crop needs for supplemental N (Schmidt et al, 2002). These practices include the timely and precise application of N fertilizer to meet plant needs varying across the landscape.…”

Digestible energy, protein and amino acid content in selected short season corn cultivars fed to growing pigs

“…The chemical and nutrient profile of corn varies widely depending on factors such as cultivar and field location (Sproule et al 1988;Singh et al 2000;Schmidt et al 2002).…”

Integration of remote sensing and crop growth modeling for nitrogen management decision support in corn

“…Although these sensing techniques have successfully identified N deficiencies, they do not effectively account for the spatially varying properties of the agricultural landscape or weather patterns that affect NO3-N losses from the agricultural system. Other researchers have attempted to develop yield response functions by regressing crop yield against soil nutrient measurements, such as late-spring NO3-N concentration (Katsvairo et al, 2003) and soil organic matter (Schmidt et al, 2002). High r 2 values for the relationship between crop yield and soil nutrient levels have not been consistently obtained with this approach, because the temporal aspects of N movement through the agricultural system cannot be adequately characterized by a single equation.…”