Print PageThe use of nitrogen fertilizers in agriculture has increased greatly in the last few decades, and subsequently so have the problems associated with higher anthropogenic inputs of nitrogen into natural ecosystems. To mitigate further pollution and destruction, there is an urgent need to better understand the dynamics involved and improve management practices with nitrogen fertilizer use in agricultural systems. This study focused on optimizing the level of summer fertilizer application in a no-till system in southeastern Minnesota, USA, by testing a range of summer fertilizer levels (34, 51, 68, 102, and 136 kg N ha-1) in corn (Zea mays L.) production. The effects of nitrogen treatment levels on soil properties, plant nutrient properties, yield, and economic returns were analyzed.
Results/Conclusions
Levels of soil nitrates (NO3--N) increased significantly with increasing levels of N inputs. Yield also increased significantly with N inputs; however, there was not a significant difference in the economic returns from the three highest levels of fertilizer applications in either of the experimental fields. There were no significant differences in other soil properties – soil moisture, percent organic matter, ammonium (NH4+), or orthophosphate (PO4-3-P) levels – across N treatments. Analyses of corn leaves showed a decrease in C:N molar ratios with increased N fertilizer treatment, and potential use of stable isotopes (15N and 13C) as indicators of nutrient sources and water stress in agroecosystems. This study demonstrated the advantages of local, on-farm research trials by obtaining specific performance data that confirm the ability of farmers to make environmentally conscious decisions, such as reducing nutrient runoff and leaching, while maintaining profitable yields and economic benefits. Such specific feedback for farmers will help promote greater understanding and wider implementation of improved nitrogen use practices.
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