Assessing variation in maize grain nitrogen concentration and its implications for estimating nitrogen balance in the US North Central region

Abstract

Accurate estimation of nitrogen (N) balance (a measure of potential N losses) in producer fields requires information on grain N concentration (GNC) to estimate grain-N removal, which is rarely measured by producers. The objectives of this study were to (i) examine the degree to which variation in GNC can affect estimation of grain-N removal, (ii) identify major factors influencing GNC, and (iii) develop a predictive model to estimate GNC, analyzing the uncertainty in predicted grain-N removal at field and regional levels. We compiled GNC data from published literature and unpublished databases using explicit criteria to only include experiments that portray the environments and dominant management practices where maize is grown in the US North Central region, which accounts for one-third of global maize production. We assessed GNC variation using regression tree analysis and evaluated the ability of the resulting model to estimate grain-N removal relative to the current approach using a fixed GNC. Across all site-year-treatment cases, GNC averaged 1.15%, ranging from 0.76 to 1.66%. At any given grain yield, GNC varied substantially and resulted in large variation in estimated grain-N removal and N balance. However, compared with GNC, yield differences explained much more variability in grain-N removal. Our regression tree model accounted for 35% of the variation in GNC, and returned physiologically meaningful associations with mean air temperature and water balance in July (i.e., silking) and August (i.e., grain filling), and with N fertilizer rate. The predictive model has a slight advantage over the typical approach based on a fixed GNC for estimating grain-N removal for individual site-years (root mean square error: 17 versus 21 kg N ha−1, respectively). Estimates of grain-N removal with both approaches were more reliable when aggregated at climate-soil domain level relative to estimates for individual site-years.

The Multifactorial Effect of Digestate on the Availability of Soil Elements and Grain Yield and Its Mineral Profile—The Case of Maize

“…The concentration of nitrogen (N c ) in maize grain was, in general, around 15 g kg −1 DW. The N c , as reported by Tenorio et al [27] for the US North-Central region ranged from 7.6 to 16.6 g kg −1 . Therefore, the value obtained can be considered as in the optimal range for maize grain.…”

Quantifying Nutrient Budgets for Sustainable Nutrient Management

“…This 10% decrease in N contents suggests that N surplus reduction in the United States estimated based on a constant N content (Zhang, Davidson, et al, ) may be overestimated by about 15 kg N ha −1 . On the other hand, Tenorio et al () estimated that yield differences explained much more variability in N surplus than variation in N concentration of harvested grain. Unfortunately, few records are available to track this critical change for most crops.…”

Toward a Regional Phosphorus (Re)cycle in the US Midwest

“…For example, a maize–soybean rotation in Illinois with a typical yield of 13.5 Mg maize ha −1 and 4.0 Mg soybean ha −1 entails removal of 36 and 22 kg P ha −1 via maize and soybean grain, respectively. Offsetting this P export of 73 kg P ha −1 for a 2‐yr maize–soybean rotation using struvite would contribute 35.7 kg N ha −1 , equivalent to 23% of the 155 kg N ha −1 needed to offset N export via grain harvest (Tenorio et al, 2018). However, a more realistic proportion of 25% of P as struvite would contribute 8.9 kg N ha −1 , 6% of total N needs.…”