Corn response to nitrogen is influenced by soil texture and weather

3 Soil properties and weather conditions are known to affect soil nitrogen (N) availability and 4 plant N uptake. However, studies examining N response as affected by soil and weather 5 sometimes give conflicting results. Meta-analysis is a statistical method for estimating treatment 6 effects in a series of experiments to explain the sources of heterogeneity. In this study, the 7 technique was used to examine the influence of soil and weather parameters on N responses of 8 corn (Zea mays L.) across 51 studies involving the same N rate treatments which were carried out 9 in a diversity of North American locations between 2006 and 2009. Results showed that corn 10 response to added N was significantly greater in fine-textured soils than in medium-textured 11 soils. Abundant and well-distributed rainfall and, to a lesser extent, accumulated corn heat units 12 enhanced N response. Corn yields increased by a factor of 1.6 (over the unfertilized control) in 13 medium-textured soils and 2.7 in fine-textured soils at high N rates. Subgroup analyses were 14 performed on the fine-textured soil class based on weather parameters. Rainfall patterns had an 15 important effect on N response in this soil texture class, with yields being increased 4.5-fold by 16 in-season N fertilization under conditions of “abundant and well-distributed rainfall.” These 17 findings could be useful for developing N fertilization algorithms that would allow for N 18 application at optimal rates taking into account rainfall pattern and soil texture, which would lead 19 to improved crop profitability and reduced environmental impacts. 20