Corn Response to Commercial Fertilizer in Cropping System Three at Lakeland, 1997

Jim Stute [1]

Introduction

During the first several growing seasons of the WICST project, corn yield in Cropping System Three was less than expected. Satellite studies were initiated in 1994 at both locations to determine if supplemental nutrients, applied as starter, side dress N or a combination could increase yield. Results through 1996 are reported in the 1996 annual report. The study was continued in 1997 at the Lakeland site only.

Materials and Methods

In 1997, the study was conducted as a satellite on plots adjacent to the core trial. Treatments included 1) no additional fertilizer, 2) starter fertilizer (as 9-23-30, 100lb/a), 3) sidedress N (as 28-0-0, 60 lb N/a), and 4) both starter and sidedress. The red clover green manure was killed the previous fall by undercutting. Secondary tillage was conducted with a single pass finishing tool on April 25 and May 21. Corn, DeKalb 247 was planted on May 21 at 34,000 kernels/acre in 30-inch rows. Starter fertilizer was applied in a band 2 inches to the side and 2 inches below the seed furrow. Supplemental N was applied as a sidedress on July 9. Weed control consisted of rotary hoeing and cultivation. Corn was harvested for grain on October 22. The experimental design was a randomized complete block with three replicates. Individual plots were 15 by 220 ft. Data were analyzed using analysis of variance, and means separated using an LSD at the 5% level of probability. A partial budget analysis approach was used to determine returns to additional nutrients using the following values: Drying – $0.02/pt to 15%; Starter – $198/ton; 28% – $157/ton; N application – $6.00/a; and Corn – $2.50/bu.

Results

Both starter fertilizer and sidedress N increased corn yield, alone and in combination, although the yield increase from a combination was not significant (Table 1). A positive yield response was expected, given the unseasonably cool conditions and slow GDD (Growing Degree Days) accumulation (see Figure 4, LAC Accumulated Corn GDD, pg.10), which presumably slowed mineralization of N from the green manure. A similar response was seen at Lakeland in 1996, also a year with below normal GGD accumulation in April and May. As in 1996, yield response was greatest where sidedress N was. From the seven site years of data in this study, it is apparent that corn following a red clover green manure responds to supplemental N in years with cool springs (Mulder, 1996). The decision to sidedress could be made easier by considering GGD accumulation to that point in the growing season and acting accordingly.

Adding starter fertilizer or supplemental N increased the gross margin, but adding both resulted in a loss (Table 1). Based on data from both locations (Mulder, 1996) it appears that sidedressing N would produce the greatest return.

Table 1.  Effect of supplemental nutrients on yield of corn following wheat/ red clover, Lakeland 1997.

* Return relative to no fertilizer once additional costs and returns are calculated.

Table 2. Corn yields from previous trials.

References

Mulder, T. 1996. Corn Response to commercial fertilizer in a low input cash grain system. 1996 WICST Technical Report, p. 36-37.

End notes

1. Agronomist, Michael Fields Agricultural Institute, East Troy, WI (414) 642-3303. Email: jstute@mfai.org

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