Irrigation, row pattern and nitrogen placement effects on corn grain yield in the Mississippi Delta

Investigators: Amilcar Vargas, Drew Gholson, Himmy Lo, Gurbir Singh, Dave Spencer, and Jason Krutz

Date: 2022

Project Summary

Introduction

Early nitrogen applications in the spring are prone to nitrogen losses due to extended periods of rainfall events. Nitrogen losses such as runoff, volatilization, denitrification, and leaching can be mitigated by following the 4R nutrient stewardship system (right source, right rate, right timing, and right place). The objective was to evaluate different nitrogen placement methods, row patterns in irrigated and rainfed on corn.

Materials and Methods

This study was conducted in 2020 and 2021 at the National Center for Alluvial Aquifer Research (NCAAR) in Leland MS. The corn hybrid DKC70-27 was planted on raised beds on very fine sandy loam for both years of the study. Corn planting dates in 2020 and 2021 were April 05, and March 19, respectively. Field was disked and hipped in the fall; beds were spaced at 40 inches. Irrigation was performed with a furrow system. Row patterns evaluated were single- and twin-row. The nitrogen placement methods chosen were surface dribble, single knife and two knives application. The nitrogen rate was split into two equal applications of 128 kg ha-1 at V2 and V6 growth stages as urea-ammonium nitrate (UAN; 32-0-0). UAN applications were performed with a four-row nitrogen applicator knife-coulter, designed to perform as a single or two knives. The surface dribble application was performed by modifying the nitrogen applicator with drop tubes. Field management operations such as tillage, weed, and pest control were conducted following Mississippi State University Extension Service recommendations. Rainfall amounts were retrieved from a weather station located at NCAAR (Figure 1). Data collected included corn grain yield, dry weight biomass, and nitrogen agronomic efficiency (NAE). Corn was harvested from the two middle rows with a plot combine equipped with a weight measuring system. Statistical analysis was performed using the statistical analysis software, SAS v. 9.4. Analysis of variance was conducted using the GLIMMIX procedure. Mean separations were performed using Fisher's protected LSD at ? = 0.05.

Research & Discussion

Corn grain yield was higher in all nitrogen placement methods in both 2020 and 2021 compared to the control (Table 1). In 2021, irrigated corn had 10% more grain yield compared to rainfed conditions. Row pattern had no effect in corn grain yield in our study. However, placing nitrogen with one knife had 13 and 7% more grain yield compared to the surface dribble and two knifes, respectively (Table 1). Furthermore, side dressing nitrogen with one knife produced the highest dry biomass, resulting in at least 9% more compared to surface dribble or two knives methods. The best method to apply UAN was with one knife-coulter (NAE = 45%), and the least efficient was surface dribble (NAE = 39%) in 2021 (Table 1). These results are consistent with other studies where surface dribble application is the least efficient method to delivered N into the soil due to N losses such as volatilization, runoff, and denitrification (Howard and Tyler, 1989; Malhi and Nyborg, 1985). Pronounced rainfall events during the spring 2021 caused nitrogen losses, which nitrogen availability in the root zone for surface dribble application (Figure 1). Our results indicate that one knife-coulter applicator is more efficient than surface dribble and two knives methods in either single or twin row pattern corn.

Literature cited

Howard, D. D., and Tyler, D. D. (1989). Nitrogen source, rate, and application method for no?tillage corn. Soil Science Society of America Journal, 53(5), 1573-1577. Malhi, S. S., and Nyborg, M. (1985). Methods of placement for increasing the efficiency of N fertilizers applied in the fall 1. Agronomy Journal, 77(1), 27-32.

• Topic:
• Irrigation Scheduling
• Irrigation