Effect of Nitrogen Supply on Maize Yield: II. Field and Model Analysis

Abstract

Abstract Experiments investigating the yield response of maize ( Zea mays L.) to applications of fertilizer N are generally analyzed empirically. While the nature of the yield response can be characterized, information on the effects of various components influencing the soil and crop N budgets are unresolved. The objective of this study was to examine the results of a series of N fertility experiments with the aid of a mechanistically based crop model. The experiments resulted in grain yields ranging from 99 to 1102 g m −2 , and these yields were well simulated by the model ( r 2 = 0.97). Under high fertility conditions, temperature and solar radiation interception explained the variation in yield among environments. Under low fertility conditions, mineralization of soil organic N was especially important in explaining yield variations among environments. Management practices preceding the experimental crops were hypothesized to have large effects on the N availability in the soil, and consequently influence observed and simulated yields. Sensitivity tests confirmed the importance of defining the initial soil organic N levels in simulating crop growth and yield when there is little or no applied N fertilizer.