Does Synthetic Fertilizer Nitrogen Application Affect in Situ Soil Organic Nitrogen Mineralization in Arable Soil?.

Synthetic fertilizer nitrogen and soil organic nitrogen mineralization are two major N sources for crop uptake. Understanding their interaction will improve soil N fertility management, which not only has direct agronomic benefits, but also has indirect environment benefits. However, most studies on this topic based on laboratory incubation study, which can’t reflect the real field conditions. Therefore, our research objective was to demonstrate the effects of synthetic N on in situ net soil nitrogen mineralization in different agriculture production systems.  In this study, in situ soil resin core method was used for field incubation. Agriculture production systems included a long term no till corn fertility study and tobacco rotation study.  Corn study site included three historical N application rates (0, 84 and 336 kg N/ha), and tobacco rotation site had six tillage and rotation systems.  In both studies, we all setted three treatment synthetic N rates in soil incubation tubes. In situ incubation study were conducted in 2012 and 2013 for tobacco study site, but only 2013 for corn study site. Result from 2013 corn site demonstrated higher historical N rate and treatment N rate can both positively promote net soil nitrogen mineralization than lower historical N rate and treatment N rate during the growth season, and result from 2012 and 2013 tobacco site showed that different amount of rainfall might affect the effect of synthetic N on net soil nitrogen mineralization.