Irrigated Corn Productivity as Influenced by Nitrogen Source, Rate, and Climatic Conditions

Abstract

Core Ideas Polymer coated N fertilizer was effective in improving crop yields. Chemical inhibitors used in the study was not effective in reducing environmental N losses. Varieties of available different chemical inhibitors may act differently and need to be compared and contrasted. Nitrogen fertilizer modifications such as coating or chemical additives are designed to either slow or inhibit N transformation, thereby to improve grain yield (GY) and reduce N losses. Effectiveness of these specialized products depend on various factors including climate. This field trial compared effects of various fertilizer modifications in irrigated corn (Zea mays L.) in loamy sand in Nebraska. Urea–ammonia–nitrate (UAN), UAN with 30% methylene–urea (UAN–MU), split‐applied UAN‐MU (UAN–MU–SP) and polymer‐coated urea (PCU) were evaluated in 2009. In 2010 and 2011, UAN with nitrapyrin (UAN–IN) and nutrisphere (UAN‐NS) and PCU were evaluated. The PCU treatment consistently improved GY compared to other N treatments in all 3 yr irrespective of inter‐annual climatic variations. In 2009, a dry year, UAN–MU and UAN were not different but UAN–MU–SP increased GY, grain and total N uptake (GNU, TNU) compared to UAN and UAN–MU. In dry (2009) and wet (2011) years, residual N did not differ by N rate while it was the greatest in the highest N rate in 2010, a normal year. The UAN–IN and UAN–NS improved GY, GNU, and TNU compared to UAN in 2010. These treatments performed as well or better than UAN, even when the UAN rate was higher. In 2011 that had high potential for N leaching, UAN–IN and UAN–NS did not increase GY compared to UAN. In extreme weather conditions, chemical additives failed to improve performance of UAN, when N was all applied after corn emergence.

Soft Red and White Winter Wheat Response to Input‐Intensive Management

“…Ferrel (2012) observed a 300% increase in soil NH 4 -N concentration when utilizing the NI dicyandiamide (DCD) as compared to Instinct. Maharjan et al (2017) observed no corn yield benefits to Instinct application despite significant rainfall occurring the day of N application and in the two weeks following N application. Previous research has observed poor Instinct performance across various cropping systems and environmental conditions (Ferrel, 2012;Franzen, 2017;Maharjan et al, 2017;Sassman et al, 2018) with authors attributing poor performance to inadequate nitrapyrin availability from microencapsulation (Ferrel, 2012;Franzen, 2017;Maharjan et al, 2017).…”

“…Despite significant rainfall following N application, NI application did not affect grain yield at either 2017 location. In spite of above average rainfall, insignificant responses to NI application following N fertilization have been observed in recent literature (Barker and Sawyer, 2017;Franzen, 2017;Maharjan et al, 2017;Sassman et al, 2018). Barker and Sawyer (2017) observed no soil NO 3 -N or corn grain yield benefits from NI application on fine-textured, poorly drained soils receiving 10.7 cm rainfall within one week of N application.…”

“…Previous research has observed poor Instinct performance across various cropping systems and environmental conditions (Ferrel, 2012;Franzen, 2017;Maharjan et al, 2017;Sassman et al, 2018) with authors attributing poor performance to inadequate nitrapyrin availability from microencapsulation (Ferrel, 2012;Franzen, 2017;Maharjan et al, 2017). Instinct has been suggested to delay release and reduce concentration of nitrapyrin during N applications and may require greater application rates than labeled to inhibit nitrification (Ferrel, 2012;Franzen, 2017;Maharjan et al, 2017). Table 5.…”

“…In addition to cool soil temperatures, the specific formulation of nitrapyrin (Instinct II; Dow Agrosciences, Indianapolis, IN) used in the current study may have contributed to the lack of response (Ferrel, 2012;Franzen, 2017;Maharjan et al, 2017). Instinct is a polymer-encapsulated form of nitrapyrin that is ineffective until nitrapyrin is released from the microcapsule (Ferrel, 2012).…”

Assessing Management of Nitrapyrin with Urea Ammonium Nitrate Fertilizer on Corn Yield and Soil Nitrogen in a Poorly-Drained Claypan Soil

“…However, few studies have reported significant increases in grain yields. One exception was Maharjan et al (2017) who observed grain yield increases with application of UAN and nitrapyrin only in one out of two years when rainfall was relatively lower. The NI might not have had significant effects on yields in those studies since they were conducted with irrigated systems and NI typically works best in soils that experience saturated conditions.…”