Corn Responds Positively to Rate & Timing of Environmentally Smart Nitrogen (ESN) & Urea

Transcription

1 Corn Responds Positively to Rate & Timing of Environmentally Smart Nitrogen (ESN) & Urea Cooperator: Smith Farm (Clay, Terry) Investigator: Dr. Morteza Mozaffari/Allen Davis Location: Greene County - Walcott Soil Series: Fontaine silt loam INTRODUCTION, BACKGROUND INFORMATION, & OBJECTIVE In 2016, approximately 745,000 acres of corn were harvested in Arkansas. Nitrogen use efficiency of conventional N fertilizers in corn production is low (< 40%), because soil and fertilizer N is subject to leaching and denitrification. These processes are enhanced in high rainfall regions with long warm growing season and under irrigated agriculture such as in Arkansas. Relatively high rates of N fertilizers are needed for producing economically optimal corn yields in Arkansas because (in addition to the various N loss mechanisms) the soil organic matter is generally low and corn yields are continuously increasing. Currently the University of Arkansas (U of A) recommends application of 220 lb N/acre for producing a corn grain yield of 220 bu/acre on silt loam soils. Improving N use efficiency by reducing fertilizer-n losses to the environment will increase profit margins. To improve N use efficiency, many Arkansas corn growers apply the recommended amount of N in three splits: 1) before or at planting, 2) at 4 to 6 leaf stage, and 3) pretassel. However, split application of N requires additional planning, labor, and equipment. In recent years, a polymer-coated urea enhanced efficiency N fertilizer has become available to Arkansas producers and is marketed under the trade name of Environmentally Smart Nitrogen or ESN (44% N, Agrium Wholesales, Denver, CO). According to the manufacturer, the N in ESN is slowly released (by temperature and moisture) over the course of the season, thus its use (as an alternative to urea) may eliminate the need for three-way split application of urea. The objective of this experiment was to evaluate corn response to split application of urea and single 7

2 application of ESN each applied at several rates on a typical soil used for corn production in northeast Arkansas. EXPERIMENTAL PROCEDURES A replicated field experiment was conducted on the Smith Farm in Before applying any of the experimental N-treatments, soil samples were collected from the 0-to 6-inch depth and composited by replication and analyzed by the standard methods of the University of Arkansas soil testing laboratory. Corn (DeKalb 67-72) was planted on flat beds on 30-March. Experimental design was a randomized complete block with five N-treatments consisting of: a 0 N control, a three way split application of 220 lb/acre urea-n (standard practice), a two way split application of 220 lb/acre ESN-N, an early single application of 220 lb/acre of ESN-N, and a late single application of 220 lb/acre ESN-N (Table 1). The first split of N was applied on 5-April (5 DAP, the second dose was applied on 17-May (47 DAP, 4-5 leaf stage), and the third was applied five days before tasseling. All post plant N treatments were applied to the plot area and incorporated into the top 2-3 inches of the soil mechanically or manually by a hoe or a rake. All the other plant nutrients were applied at recommended rate to ensure that N is the only nutrient limiting potential corn grain yield. Each test plot was 25-ft long and 10-ft wide allowing for four rows of corn planted in 30-inch wide rows. Corn irrigation, pest control and other cultural practices were managed by the farmer. We hand harvested the corn ears in one 12-ft section of corn plants in each of the two center rows of each plot on 4-Aug. The harvested corn ears were ran through the combine later and the yields were calculated at 15.5% moisture. Analysis of variance (ANOVA) was performed to evaluate the effect of N treatment on corn grain yield. When appropriate, significant differences among the means were separated by the least significant difference (LSD) test with significance interpreted at the 0.10 level. RESULTS AND DISCUSSION Total monthly rainfall from April to August was inches which was above the 10-year average for the experimental site. Therefore, the conditions were conducive 8

3 for above normal N loss via leaching, runoff, denitrification and additional N loss may have occurred through irrigation. Soil ph was 6.1 and Mehlich-3 extractable P and K were 36 and 115 ppm respectively. Nitrogen treatment significantly influenced corn grain yield (P=0.0002, Table 2). The grain yield of corn that did not receive any N was 80 bushel/acre. The grain yield of corn fertilized with 220 lb/acre of N ranged from 175 to 213 bu/acre (Table 2). Three way split application of 220 lb/acre of urea-n resulted in significantly higher yields (208 bu/acre) than treatments that received 220 lb/acre of ESN-N either five DAP, or a two way split 220 lb/acre of ESN-N. However, there was no significant difference in grain yield of corn that received 220 lb/acre of urea-n in a three way split and corn that received the same amount of N in one single application from ESN at 47 DAP. Numerically the highest grain yields were produce with a three way split of 220 lb/acre of urea-n or a single application of ESN-N at 47 DAP. Results of this one-year, one-site study suggest that a single application of ESN-N might potentially be an agronomically sensible alternative to the conventional three way split application of urea-n. However, given the large acreage and diversity of corn production systems in Arkansas, additional replicated field trials at multiple sites and years are needed to confirm or deny the reproducibility of these results. ACKNOWLEDGMENTS We appreciate the cooperation of Mr. Terry and Mr. Clay Smith. This research was supported by Agrium Wholesales and the University Of Arkansas System Division Of Agriculture. DISCLAIMER Trade name(s) are used in this document to facilitate communication only and do not express or imply endorsement of any product when another product may perform similarly. 9

4 10 Table 1. Detailed experimental treatments for a field experiments that evaluated corn response to timing and rate of urea-n and ESN- N application at Terry Smith s farm in Greene County, Arkansas in Treatment First N application (Pre-plant) Second N Application Third N application (Pre-tassel) Total N applied N source-rate (lb N/acre) none none none 0 2 Urea-120 Urea_50 Urea_50 Urea_220 3 ESN _120 ESN_100 none ESN_220 4 ESN_220 none none ESN_220 5 none ESN_220 none ESN_220 a The first split of N was applied on 5-April (5 DAP) and the 2 nd dose of N was applied on 17-May (47 DAP).

5 11 Table 2. Corn grain yield response to timing and rate of urea-n and ESN-N application for a replicated field experiments that evaluated corn response to timing and rate of urea-n and ESN-N application at Terry Smith s farm in Greene County, Arkansas in Treatment Pre-plant V4-V6 Pre-tassel Total N rate Corn Grain yield N source-rate (lb N/acre) total N lb/acre (bu/acre) none none none 0 80 C 2 Urea-120 Urea_50 Urea_50 Urea_ A 3 ESN _120 ESN_100 none ESN_ B 4 ESN_220 none none ESN_ B 5 none ESN_220 none ESN_ A P value a Means followed by the same letter were not significantly different at P 0.1.