Meta-Analysis of Weather Effects on Corn Nitrogen Fertilization Requirements

Abstract：Meta-Analysis is an expression used to identify a set of statistical techniques developed to provide an objective comparison of research results from independent studies.A meta-analysis combines the results of several studies that address a set of related research hypotheses.In this study,a meta-analysis was performed on the relationship between the application rates of nitrogen fertilizer and the corn yield response in order to understand the effects of climate（air temperature,rain） and environmental conditions（latitude,soil surface textures）.The climate influenced nitrogen requirements.Corn grown on silt clay loams,and to a smaller extent on silt loams,were most responsive to added N.Latitudes from 39°N to 42°N were the most favorable to corn N response.During the first two months of corn growth,the effect of rain evenness on N response was larger than that of temperature or precipitation.For the mid-season period,the effect of precipitation was higher than the ones of temperature and rain evenness.For the last part of the growing season,all three factors were of equally importance for N response.