Effects of Balancing Nitrogen Rate and Timing on Corn Productivity
Agronomy & Pest Management
Ramandeep Kumar Sharma
County Agent (Faculty)
Rutgers University
Woodstown
Abstract
Improved corn yields and profitability are tied to efficient nitrogen (N) management. Nitrogen is applied in one/two splits in New Jersey corn. Yet, there is increasing interest in exploring the suitability of additional split applications in enhancing N utilization efficiency and grain yield. More split applications of N are tied to better agronomic potential but also linked with increased operational costs. This study was focused on assessing the economic and agronomic balance of increasing N split frequency from two to four applications in corn. Field trials were conducted to equate three total N rates (150, 200, 250 lbs./acre) against three split arrangements: 2 (50% N at V2 + 50% N at V6), 3 (33% N at V2 + 33% N at V6 + 33% N at VT), and 4 (25% N at V2 + 25% N at V6 + 25% N at VT + 25% N at R1)-way splits. Research experiments were conducted following a randomized complete block design, testing the aforesaid treatments, making ten (including a check plot with no N) treatments replicated four times in plots sized 30 feet long by 10 feet wide. The data on grain yield, N costs, labor/equipment costs per operation, and net return on investment (ROI) per acre were collected and analyzed. Agronomic optimum N rate was noted to be 228 lb/ac. Economically optimum N rate was calculated as 159 lb/ac. Relatively high nitrogen prices compared to corn prices result in an economically optimal nitrogen rate that is lower than the agronomic optimum. Higher corn prices increase the economically optimal nitrogen rate, with optimal N rising from approximately 142–159 lb/ac at low corn prices to 159–169 lb/ac at high corn prices. The economically optimal nitrogen rate is more sensitive to corn price changes when urea prices are high. The economically optimal nitrogen rate (159 lb/ac) is substantially lower than the agronomic optimum (228 lb/ac), reflecting current high nitrogen prices relative to corn prices. While three split applications generate higher average revenue than two splits ($59/ac), increasing to four split applications does not result in additional revenue gains.
Authors: Ramandeep Kumar Sharma, Seowee Lee
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Ramandeep Kumar Sharma County Agent (Faculty), Rutgers Cooperative Extension, New Jersey, 08098-9982
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Seowee Lee Extension Specialist in Ag Viability, Rutgers University, New Jersey, 08901