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Effect of nitrogen supply on maize yield. II. Field and model analysis

Muchow, R.C., Sinclair, T.R.
Agronomy journal 1995 v.87 no.4 pp. 642-648
Zea mays, growth models, mathematical models, simulation models, crop yield, nitrogen fertilizers, soil fertility, nitrogen content, nutrient uptake, grains, Northern Territory
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 (r2 = 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.