Disentangling management factors influencing nitrogen balance in producer fields in the western Corn Belt

The nitrogen (N) balance provides an indication of the risk for N losses into the environment. Previous studies have shown large variation in N balance among producer maize fields in the US Corn Belt, even within the same region and year. However, little is known about the soil and management factors explaining variation in N balance and to what extent the influence of these factors on N balance occurs via grain yield, N inputs, or both. This study aimed to disentangle interactions among yield, management practices, and soil factors to identify which have the greatest influence on N balance in producer maize fields in Nebraska (USA). The database used contains yield and management records from 311 producer irrigated and rainfed fields sown with maize for two years (2010−2011). The N balance was estimated as the difference between N inputs (from fertilizer and applied irrigation) and grain N removal. Random forest regression and path analysis were used to assess the influence of soil and management factors on the N balance via either grain yield or N inputs for irrigated and rainfed fields. Analysis based on combination of advanced statistics showed that soil organic matter (SOM), seeding rate, sowing date, and in-season N sidedress influenced N balance, mostly via N inputs application and, to a lesser degree, grain yield. In many cases, producer risk behavior explained the relationship between N balance and soil and management factors. For example, N application was higher in fields that have lower SOM or received in-season N sidedress, without any yield advantage. The findings suggest that efforts are needed to help producers manage N inputs more efficiently and deal with the associated risks. Our study performed a novel field level assessment of factors influencing N balance which provides useful information in prioritization of agricultural research and extension programs to avoid large N balances and associated negative environmental impact. [Display omitted] •There was large variation in nitrogen (N) balance across fields even within the same region and year in the US Corn Belt.•This study assessed which management and soil factors had greatest influence on N balance using producer data and advanced statistical analyses.•Sowing date, seeding rate, in-season N sidedress, and soil organic matter influenced N balance via N inputs and, to a lesser degree, yield.•Efforts are needed to help producers manage N inputs more efficiently and deal with the associ