Aerial nitrogen fluxes and soil nitrate in response to fall-applied manure and fertilizer applications in eastern South Dakota

Authors: MEHATA, MUKESH - South Dakota State University; CORTUS, ERIN - South Dakota State University; NIRAULA, SURESH - North Dakota State University; Spiehs, Mindy; DARRINGTON, JOSEPH - South Dakota State University; CHATTERJEE, AMITAVA - North Dakota State University; RAHMAN, SHAFIQUR - North Dakota State University; Parker, David

Submitted to: International Journal of Agronomy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2019
Publication Date: 9/22/2019
Citation: Mehata, M., Cortus, E., Niraula, S., Spiehs, M.J., Darrington, J., Chatterjee, A., Rahman, S., Parker, D.B. 2019. Aerial nitrogen fluxes and soil nitrate in response to fall-applied manure and fertilizer applications in eastern South Dakota. International Journal of Agronomy. 2019:8572985. https://doi.org/10.1155/2019/8572985.
DOI: https://doi.org/10.1155/2019/8572985

Interpretive Summary: Nitrogen is an essential nutrient for plant growth. It is often applied to corn fields in the form of livestock manure or a commercial fertilizer such as urea. While nitrogen is needed to produce the crop, excess nitrogen application can be responsible for nitrogen losses to the environment. Nitrogen can be lost into the atmosphere as ammonia or nitrous oxide and can be leached through the soil as a nitrate. Ammonia is an odorous compound and can also cause health issues for humans and animals. Nitrous oxide is a greenhouse gas. Nitrates can leach into ground water or run off into surface water causing health problems from humans and aquatic life. Therefore, it is important to know the fate of nitrogen that is land applied to cropland. There is evidence to suggest that the nitrogen from manure breaks down more slowly, which may reduce the losses to the environment. A study was conducted to determine the fate of nitrogen when nitrogen was applied to a corn field as either a commercial fertilizer or in the form of beef manure. Two types of beef manure were applied, one had bedding mixed into the manure and one did not. The fertilizer was applied to fields that were planted to corn and measurements were taking during the growing season. There were not differences in the corn yield when commercial fertilizer, manure, or no fertilizer were applied to the corn fields. Nitrate content in the first 6 inches of soil and up to 24 inches in depth were higher when a commercial fertilizer was used compared to manure or no fertilizer. Nitrous oxide emissions were also higher when commercial fertilizer was used compared to not using any fertilizer. When manure with bedding materials mixed with it was used as a fertilizer, ammonia emissions were higher than when no fertilizer was used. The results demonstrate no differences in nitrogen losses to the environment between the three nitrogen sources (commercial fertilizer, beef manure with bedding, and beef manure without bedding), but some additional nitrogen losses can be expected when a fertilizer is used compared to no fertilizer application.

Technical Abstract: Manure and inorganic fertilizer help to meet crop nitrogen demand by supplementing soil nitrogen (N). However, excessive N losses reduce soil fertility and crop yield and can impair water and air quality. The objectives of the research were to compare different forms of fall-applied N for (1) the change in soil nitrate (NO3-N) over the growing season and (2) the aerial ammonia (NH3) and nitrous oxide (N2O) fluxes during the fall and early growing season. Treatments included solid beef cattle manure with bedding (BM), solid beef cattle manure only (SM), urea (UO), and no fertilizer (NF). The two-year plot-scale study took place in Brookings County, South Dakota, under rain-fed conditions in a silty clay loam. Manure and urea were applied at equal plant-available N rates of 130 and 184 kg·N·ha-1 in Y1 and Y2, respectively, according to the South Dakota nutrient management planning process. The average total (i.e., 0–0.60m soil depth) soil NO3-N for Y1 (83 kg·ha-1) was significantly higher than Y2 (67 kg·ha-1), whereas surface (i.e., 0–0.15m soil depth) soil NO3-N was not significantly different between years. The average surface soil NO3-N (33.5 kg·ha-1) and total soil NO3-N (105.0 kg·ha-1) for UO were significantly higher than the remaining treatments (P < 0.05). Soil water NO3-N concentrations, leaf-N, corn-grain-N, and yield measurements did not indicate any significant differences between treatments. Based on the two-year average, the highest NH3-N flux occurred from the BM (3.4 g·ha- 1·h-1); however, this flux was only significantly higher than NF (1.4 g·ha-1·h-1). The NH3-N fluxes from UO (2.2 g·ha-1·h- 1) and SM (1.7 g·ha-1·h-1) were similar to both BM and NF. The N2O-N flux from UO (0.79 g·ha-1·h-1) was significantly greater than NF (0.25 g·ha-1·h-1), while BM- (0.49 g·ha-1·h-1) and SM-produced (0.33 g·ha-1·h-1) N2O-N fluxes were not significantly different than neither UO nor NF. The three fall-applied N sources had similar aerial-N fluxes even though urea application resulted in significantly higher soil nitrate.