The University of Missouri recently initiated research on twin- and narrow-row corn production in Northeast Missouri. The purpose of this research was to determine: 1) grain yield of twin-row corn compared with 30 in. wide-row corn planted with the Precision Seeding System™ and a 30 in. wide-row corn planter, 2) the effect of corn row spacing and planting population using the Precision Seeding System™ on final corn plant population and grain yield compared with a 30 in. wide-row planter in a no-till and conventional tillage production system, 3) the effect of twin-row corn plant placement and population on corn grain yield, and 4) the effect of twin- compared to narrow-rows on late planted soybean light interception, leaf area, and grain yield. The results from this research will be useful in evaluating the cost effectiveness of twin- and/or narrow-row corn, and will build on previous research evaluating narrow-row corn.

Figure 1. Twin-row corn planting configuration.	Figure 2. Twin-row soybean planting configuration.

The Precision Seeding System™ was introduced by Great Plains in 2000 as a new seed delivery system for planting several crops. The system allows a farmer to utilize a single planter for all crops and pursue numerous crop row spacings. A farmer can convert to a narrower row spacing like twin-rows and still utilize a 30 in. corn head for harvest with the new seeding system. In a twin-row planting configuration, two 7.5 in. rows are planted on 30 in. centers with 22.5 in. between rows (Figure 1 and 2).

Methods:

The Great Plains 1510P Precision Seeding System™ planter was equipped with a center pivot hitch, monitor, and no-till coulters. Rainfall for the University of Missouri Greenley Research Center is available at http://aes.missouri.edu/greenley/fieldday/page3.stm. The following studies were labeled according to the crop, research study number, and year (Corn; 03, study #3; 01, 2001 research).

Corn0301. Effect of corn row spacing and population on no-till corn grain yield. (Novelty, MO)

Research was arranged as a split-plot design with four replications. The main plots were corn row spacing and subplots were planting population. Corn was planted at 7.5" wide-, 15" wide-, 22" wide-, twin-, and 30" wide-row spacings with a Great Plains 1510P Precision Seeding System™, and 30" wide-row corn was planted with a John Deere 7000 planter. All row spacing configurations were planted at 25,000, 30,000, 35,000, and 40,000 seeds/acre. All plots received a broadcast application of 150-50-100 fertilizer on April 27, 2001. Garst 8342IT was no-till planted into soybean stubble approximately 1.25 in. deep on April 28, 2001 in 15 by 40 ft plots. A burndown treatment of Roundup UltraMax at 26 oz/acre plus ammonium sulfate at 2.5 lbs/acre plus 2,4-D ester at 1 pt/acre was followed with Bicep II Magnum at 2.5 qt/acre applied preemergence for weed control. All plots were harvested with a Massey 10 combine. The grain table was equipped with Mi-Co-Flo™ (http://www.sunflowereq.com/) grain table attachment which allowed harvest of all crop row spacings (Figure 3). Moisture and grain yield were determined and final yield adjusted to 15.5% moisture.

Figure 3. Mi-Co-Flo™ grain table attachment for milo, corn, and sunflowers used to harvest all corn row spacings.

Corn0401. Effect of corn row spacing and population on conventional-till corn grain yield. (Novelty, MO)

Research was arranged as a split-plot design with three replications. The main plots were corn row spacing and subplots were planting population. Corn was planted at 7.5" wide-, 15" wide-, 22" wide-, twin-, and 30" wide-row spacings with a Great Plains 1510P Precision Seeding System™, and 30" wide-row corn was planted with a John Deere 7000 planter. All row spacing configurations were planted at 25,000, 30,000, 35,000, and 40,000 seeds/acre. The field was fall chisel plowed, spring disked, field cultivated twice, cultipacked, and fertilized with 160-50-100. Pioneer 34B24 was planted approximately 1.25 in. deep on May 17, 2001 in 15 by 40 ft plots. Bicep II Magnum at 2.5 qt/acre was applied preemergence for weed control. All plots were harvested with a Massey 10 combine. The grain table was equipped with Mi-Co-Flo™ grain table attachment which allowed harvest of all crop row spacings. Moisture and grain yield were determined and final yield adjusted to 15.5% moisture.

Corn0501a. Grain yield of twin- compared with 30" wide-row corn. (Novelty, MO)

Research was arranged as a randomized complete block design with four replications. Corn was planted at 30,000 seeds/acre in twin- and 30"-wide rows with a Great Plains 1510P Precision Seeding System™, and 30" wide-rows with a John Deere 7000 planter. All plots received 160-50-100 fertilizer on April 27, 2001. Garst 8464IT was no-till planted into soybean stubble approximately 1.25 in. deep on May 16, 2001 in contour plots 15 by 1500 ft. All plots were harvested with an R50 Gleaner combine and grain yield was determined using an Ag Leader™ yield monitor. Bicep II Magnum at 2.5 qt/acre plus Roundup UltraMax at 26 oz/acre plus 2,4-D ester at 1.5 pt/acre plus Princep at 1 qt/acre was applied preemergence. This was followed by Atrazine at ½ lb/acre plus 2,4-D ester at ½ pt/acre applied postemergence for weed control.

Corn0501b. Grain yield of twin- compared with 30" wide-row corn. (Novelty, MO)

Research was arranged as a randomized complete block design with four replications. Corn was planted at 30,000 seeds/acre in twin- and 30" wide-rows with a Great Plains 1510P Precision Seeding System™, and 30" wide-rows with a John Deere 7000 planter. All plots received 160-50-100 fertilizer on April 27, 2001. Burrus BX65 was no-till planted into clover stubble approximately 1.25 in. deep on May 17, 2001 in contour plots 15 by 1200 ft. All plots were harvested with an R50 Gleaner combine and grain yield was determined using an Ag Leader™ yield monitor. Bicep II Magnum at 2.5 qt/acre plus Roundup UltraMax at 26 oz/acre plus 2,4-D ester at 1.5 pt/acre plus Princep at 1 qt/acre was applied preemergence. This was followed by Atrazine at ½ lb/acre plus 2,4-D ester at ½ pt/acre applied postemergence for weed control.

Corn1301. Grain yield of twin- compared with 30" wide-row corn. (Palmyra, MO)

Research was arranged as a randomized complete block design with eight replications at the Wayne Bier Farm. Mycogen 6888 was planted 1.25 in. deep on April 9, 2001 at 30,000 seeds/acre in twin-rows with a Great Plains 1510P Precision Seeding System™ and 30" wide-rows with a Kinzie planter in plots 15 by 380 ft. The field was field cultivated and fertilized with 200-70-150. Degree Xtra was applied for weed control. All plots were harvested with a R62 Gleaner combine. Grain yield was measured using a weigh wagon and moisture was determined for each plot. Final grain yield was adjusted to 15.5%.

Corn0601. Effect of twin-row corn plant placement and population on grain yield. (Novelty, MO)

Research was arranged as a split-plot design with four replications. The main plot was row spacing and subplots were population. Corn was planted at 50,000 to 70,000 seeds/acre in twin- and 30" wide-rows with a Great Plains 1510P Precision Seeding System™, and 30" wide-rows with a John Deere 7000 planter. The field was fall chisel plowed, spring disked, field cultivated, and fertilized with 160-50-100. Burrus 671RR was planted into a stale seedbed approximately 1.25 in. deep on June 13, 2001 in plots 15 by 70 ft. Plots were thinned to 25,000 and 35,000 plants/acre when corn was at the V3 stage of development. Bicep II Magnum at 2.5 qt/acre plus Roundup UltraMax at 26 oz/acre was applied preemergence for weed control. All plots were harvested with a Massey 10 combine. Moisture and grain yield were determined and final yield adjusted to 15.5% moisture.

Soy1001. Influence of twin- and narrow-rows on late planted soybean grain yield (Novelty, MO).

Late planted twin-row soybean was compared with 7.5, 15, and 22 in. row spacings planted at 140,000 and 200,000 seeds/acre. Research was arranged as a split-plot design with four replications. The main plot was row spacing and subplots were population. Pioneer 94B01 soybean were no-till planted with a Great Plains 1510P Precision Seeding System™ on June 17, 2001 in plots 7.5 by 50 ft. All plots were harvested with a Massey 10 combine. Moisture and grain yield were determined and final yield adjusted to 13% moisture.

Statistical Protocol:
Objective 1. Determine grain yield of twin-row corn compared with 30 in. wide-row corn planted with the Precision Seeding SystemTM and a 30 in. wide-row corn planter. Data from plots with corn planted in twin-rows with the Great Plains 1510P Precision Seeding System™ and 30" wide-rows with a planter seeded at 30,000 seeds/acre (Corn0301, Corn0401, Corn0501a, Corn0501b, and Corn1301) were subjected to analysis of variance and means separated using Fishers's Protected LSD (p<0.05). Each study was considered a separate location. Grain yield data were combined over location since no interactions were observed; however, population was presented separately for each location due to an interaction between treatments and location. A separate analysis evaluated data from plots with corn planted in twin- and 30" wide-rows with the Great Plains 1510P Precision Seeding System™ and 30" wide-rows with a planter at 30,000 seeds/acre (Corn0301, Corn0401, Corn0501a, and Corn0501b).

Objective 2. Determine the effect of corn row spacing and planting population using the Precision Seeding System™ on final population and grain yield compared with a 30 in. wide-row planter in a no-till and conventional tillage production system. Corn0301 (no-till) and Corn0401 (conventional-till) were subjected to an analysis of variance and means separated using Fishers's Protected LSD (p<0.05). Each study was considered a separate location. Data were presented separately due to an interaction between planted population and location. However, there was no interaction for row spacing yield data; therefore, means were pooled over location and population.

Objective 3. Determine the effect of twin-row corn plant placement and population on corn grain yield. Corn0601 was subjected to an analysis of variance and means separated using Fishers's Protected LSD (p<0.05). No interactions were observed; therefore, the main effects for row spacing and population were presented.

Objective 4. Determine the effect of twin- compared to narrow-rows on late planted soybean light interception, leaf area, and grain yield. Soy1001 was subjected to an analysis of variance and means separated using Fishers's Protected LSD (p<0.05).

Results:
Objective 1. Final corn population of twin-row corn was similar (3 tests) or reduced (2 tests) up to 40% compared to 30" wide-row corn planted with a corn planter (Table 1). The population reduction in Corn0301 was probably due to an extended period of cool wet soils after planting. Grain yield was 11 bu/acre greater with a 30" wide-row corn planter compared to twin-row corn. Corn grain yield differences were probably related to the final corn population of twin- compared with 30" wide-row corn.

Table 1. Population reduction and grain yield of twin- and 30" wide-row corn planted with the Great Plains 1510P Precision Seeding System™ and 30" wide-row planter, respectively (Corn0301, Corn0401, Corn0501a, Corn0501b, and Corn1301).

Objective 1. Final corn population and grain yield of twin-row corn was similar to 30" wide row corn planted with the Precision Seeding System™ (Table 2). No difference in corn grain yield between 30" wide-row corn planted with the Precision Seeding System™ or John Deere 7000 planter was observed. Twin-row corn was contour planted between terraces (Corn0501a, Corn0501b). We did not encounter any harvesting difficulties with the twin-row corn using a 6-row corn head. Harvesting speed was similar for the twin-row corn compared with 30" wide-row corn.

Table 2. Population reduction and grain yield of twin- and 30" wide-row corn planted with the Great Plains 1510P Precision Seeding System™ and 30" wide-row corn planted with a John Deere 7000 planter (Corn0301, Corn0401, Corn0501a, Corn0501b).

Objective 2. Corn population was reduced in plots planted with the Precision Planting System compared to a 30" wide-row planter. The population reduction in Corn0301 was probably due to an extended period of cool wet soils after planting. The no-till coulters planter units caused more soil disturbance than the planter. If this is followed by a rain or extended wet periods, the planting depth was probably greater with the Precision Planter than the 30" wide-row planter. There was no difference in final population when favorable conditions followed planting (Corn0401). Corn grain yield was 26 bu/acre greater in 30" wide-row corn than 7.5 and 22 in. row spacings when data were pooled over location (Figure 4).

Corn grain yield was 124 bu/acre at a final plant population of 22,600 plants/acre in the no-till study. The optimum plant population was 25,000 in the conventional tillage study.

Table 3. Final population and grain yield of 7.5, 15, 22, 30, and twin-row corn planted with the Great Plains 1510P compared with 30" wide-row corn planted with a John Deere 7000. Corn0301 was no-till planted into soybean stubble and Corn0401 was planted into a conventional tillage stale seed bed. Row spacing data were averaged over population and population data were averaged over row spacing.

Figure 4. The influence of row spacing on corn grain yield. No interactions between row spacing, location, and population were observed; therefore, row spacing data were averaged over location and planted population. Abbreviations: PPS, Great Plains Precision Seeding System™;JD, John Deere 7000.

Objective 3. This research was planted at 50,000 to 70,000 seeds/acre and plots were hand thinned to 25,000 and 35,000 plants/acre when corn plants were at the V3 stage of development. Seed placement as parallel or alternating plants in the twin-row planting configuration did not affect corn grain yield (Table 4). Corn grain yield for twin-rows planted with the Precision Seeding System™, 30" in. wide-rows planted with the Precision Seeding System™, and 30" wide-rows planted with a John Deere 7000 planter was similar when the final plant population was the same.

Table 4. The influence of plant placement on twin-row corn grain yield compared with 30" in. wide-row corn (Corn0601). No interactions were observed; therefore, row spacing data were averaged over population and population data were averaged over row spacing.

Objective 4. Determine the effect of twin- compared to narrow-rows on late planted soybean light interception, leaf area, and grain yield. Light interception six weeks after planting in the twin-, 15 in., and 7.5 in. row configurations was 14 to 17% greater than 22 in. soybean. Similarly, the leaf area of soybean in the twin-, 15 in., and 7.5 in. row configurations was greater than 22 in. soybean. Late planted soybean grain yield was greatest in 7.5 in. row spacing planted at 200,000 seeds/acre. Twin-row soybean grain yield was similar to 15 in. row spacing.

Table 5. Effect of seeding rate and soybean row spacing on late planted soybean light interception (LI), leaf area index (LAI), and grain yield (Soy1001). There was no interaction between row spacing and seeding rate for LI and LAI; therefore, data were averaged over seeding rate.^a

Discussion:

The Precision Seeding SystemTM allows a farmer to utilize one planter to plant corn and soybean. Narrow-row corn and soybean usually have quicker canopy closure which may increase weed control and allow better sunlight utilization. Numerous studies have documented that corn grain yield is usually related to the final plant population at harvest. The seeding rate for the Precision Seeding SystemTM may need to be increased under suboptimal planting conditions. However, grain yield was comparable under optimal planting conditions and similar plant populations when the Precision Seeding SystemTM was compared to a typical corn planter. This research evaluated several corn varieties in separate evaluations. We believe additional research is needed to determine the influence of corn variety on twin- and narrow-row corn production in Northeast Missouri and reinforce the results of this research.

For further information, please contact Kelly Nelson (nelsonke@missouri.edu) or Randall Smoot (smootr@missouri.edu) at the University of Missouri Greenley Research Center (660-739-4410), P.O. Box 126, Novelty, MO 63460. This research was initiated to provide an unbiased evaluation and does not constitute an endorsement of any product.

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