Corn Response to Application Timings of N Sources and Rates of Esn in Northeast Missouri

An increase in government regulations of anhydrous ammonia and ammonium nitrate may affect the availability and price of these nitrogen sources in the future. This research evaluated corn response to timings of N sources and rates of ESN in Northeast Missouri.

This study was arranged as a randomized complete block design in plots 10 by 50 ft with four replications on a Putnam silt loam soil near Novely, MO in 2005. The field location was selected due to soil conditions that may encourage N loss due to denitrification. The field was flat with relatively poor internal drainage. A broadcast application of 30-80-120 was made on March 31, 2005. Asgrow ‘RX 752YG/RR’ corn was no-till planted at 30,000 seeds/acre in 30 inch rows on May 3, 2005. Nitrogen sources were broadcast applied four weeks prior to planting on April 5 (early preplant), at planting on May 3 (preplant), and approximately four weeks after planting on June 3 (sidedress), except anhydrous at the sidedress timing. ESN was applied at 50, 75, 100, and 150 lbs/a. Other nitrogen sources were broadcast applied at 150 lbs N/acre. Anhydrous was knife injected following mole knives. Rainfall events for the period were reported in Figure 1. All data were subjected to analysis of variance and means separated using Fisher’s Protected LSD (p=0.05). The concentration of protein, oil, starch, and grain density was determined with a Foss Infratec1241 near-infrared reflectance grain analyzer.

Weather conditions prevented fall application timings in 2005. There was no effect of N application timing or ESN rate on corn population density or grain oil in 2005 (data not presented). Reduced rates of ESN at an early preplant timing had a greater yield reduction than preplant or sidedress application timings (Figure 1). Low rates of ESN at the sidedress timing had grain yields similar to the highest yielding sidedress ESN treatment (Table 1). ESN at 150 lb N/acre had grain yields similar to the other N sources at the same application rate. Corn grain protein with ESN at 150 lb/a was greater than or equal to all early preplant and preplant N source application timings except a preplant anhydrous ammonia application (Table 2). In general, protein content was greatest with all sidedress application of N sources except ESN at 100 and 150 lb N/acre. There was an inverse relationship between starch and protein (Tables 2, 3). High starch corn had low protein levels. There was no rate response of ESN on starch levels at the preplant and sidedress application timings. Corn grain density was greater than 1.28 for all treatments except preplant ESN at 50 and 75 lb/a and sidedress ESN at 50 lb/a (Table 4). ESN at 100 lb N/a had starch, grain yield, and grain density similar to 150 lb/a; however, protein levels were greater at 150 lb/a at all application timings.

Research in 2006 was expanded to include rates of urea along with rates of ESN. In addition, fall applied treatments were included.

Table 1. Corn grain yield for ESN rates and N sources applied early preplant (April 5), preplant (May 3), and sidedress (June 3) in 2005.

^aTreatment was not applied.

Table 2. Corn grain protein for ESN rates and N sources applied early preplant, preplant, and sidedress in 2005.

^aTreatment was not applied.

Table 3. Corn grain starch for ESN rates and N sources applied early preplant, preplant, and sidedress in 2005.

^aTreatment was not applied.

Table 4. Corn grain density for ESN rates and N sources applied early preplant, preplant, and sidedress in 2005. Density is a common measurement for food grade corn grain quality. Values greater than 1.28 are desirable.

^aTreatment was not applied.

Figure 1. Rainfall at the Greenley Research Center at Novelty, MO for 2005.

Figure 2. The effect of ESN rate applied early preplant (4 weeks before planting), preplant (at planting), and sidedress (4 weeks after planting) timings on corn grain yield in 2005. LSD (p=0.05) was 22.

2006 Field Day Report