|THAPA, RESHAM - North Dakota State University|
|CHATTERJEE, AMITAVA - North Dakota State University|
|AWALE, RAKESH - North Dakota State University|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/21/2015
Publication Date: 5/19/2015
Publication URL: http://handle.nal.usda.gov/10113/61118
Citation: Thapa, R., Chatterjee, A., Johnson, J.M., Awale, R. 2015. Stabilized nitrogen fertilizers and application rate influence nitrogen losses under rainfed spring wheat. Agronomy Journal. 107(5):1885-1894. DOI:10.2134/aj15.0081.
Interpretive Summary: Wheat is a major food crop that needs nitrogen (N) fertilizer to maintain its yield. Ideally all the N a farmer pays to put on the field would promote yield. Producers experience an economic loss if some of the N applied is lost rather than being used by the crop because they have to apply fertilizer at higher rates. Nitrogen can be lost to the air as nitrous oxide or ammonia. It can be lost in water as nitrate. When the N is lost into the air or water, it has undesired environmental effects. But there are tools farmers can use to help prevent or reduce such losses. One tool is the use of inhibitors that slow or stop the conversion of fertilizer N into forms that are lost more easily. Other studies were on lands that were irrigated. Therefore, we studied how well two inhibitors may work on rainfed wheat. This single growing-season study under rainfed, silt-loam soil conditions found that these two inhibitors can be used successfully to minimize N losses without compromising grain yield and quality. This study demonstrates it is possible to reduce N loss. The results suggest that use of inhibitors should be studied at other rainfed sites and over multiple years to determine the consistency of the response. This work will benefit the fertilizer industry, producers and other scientists as it may reduce farmer expenses and help protect the environment.
Technical Abstract: Nitrogen (N) losses associated with fertilizer application have negative economic and environmental consequences, but urease and nitrification inhibitors have potential to reduce N losses. The effectiveness of these inhibitors has been studied extensively in irrigated but not rainfed systems. Therefore, this study was conducted under rainfed conditions to compare the effects of urea (U), stabilized urea with urease and nitrification inhibitor (SU), and stabilized urea with nitrification inhibitor (UI), each applied at two varying rates of 146 and 168 kg N ha-1, on N2O-N emissions, NH3 volatilization NO3- leaching, grain yield and protein content of spring wheat under rainfed conditions. Cumulative N2O emissions, NH3 volatilization, and NO3- leaching were significantly reduced by 50%, 26%, and 30%, respectively with SU compared to U, but UI only reduced cumulative NO3- leaching by 30% compared to U. Fertilizer N rate did not affect N2O emissions, but lower N application rate (146 kg N ha-1) significantly reduced NH3 volatilization and NO3- leaching by 26% and 30% respectively compared to 168 kg N ha-1. Nitrogen source and N-rate did not influence grain yield and protein content. Under the experimental conditions prevailed during this study, these results showed the ability of SU and UI in reducing all or particular form of N losses, delaying N transformation processes from urea fertilized soils without hampering grain yield and protein content. This single growing-season study under rainfed, silt-loam soil conditions found that fertilizer N-stabilizers can be used successfully to minimize N losses without compromising grain yield and protein content.