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Bruce Burdick
1109 S. Birch St.
Albany, MO 64402
660-726-5610
Email: BurdickB@missouri.edu

Hundley-Whaley Center phone
660-726-3698

EFFECT OF ULTRA-EARLY SOYBEAN PLANTING DATES ON SOYBEAN PRODUCTION ECONOMICS (VERP)

Summary: This study was initiated to test the hypothesis presented in the November issue of The Furrow (Volume 104, Issue 7, PP31-32). The report suggested that ultra-early, no-till soybean plantings would survive early spring frosts. Such a practice, if successful, could be beneficial to northwest Missouri soybean producers. It could spread the workload and possibly lead to increased crop performance.

The results of two years of testing indicates that early planted soybeans would perform as well as those planted in mid-spring regardless of whether they were tilled or no-till. There was no late-spring frost to inhibit soybean stand or growth in either 2000 or 2001. The two year of data shows that soybeans at the Hundley-Whaley Farm performed equally well when planting dates ranged from late March through the end of May in disked plots.

Methods: The study was designed and analyzed with Gylling's Agriculture Research Manger 6.1, and it consisted of twenty treatments to compare the effect of ultra-early planting verses normal planting.

Merschman Cleveland VI RR was used as the variety of choice in 2001. Merschman Houston V RR was selected for use in 2000. Each year's seed was factory treated with Rival and Allegiance fungicides (Captan, PCNB, Thiabendazole and Metalaxy) at manufacturer recommended rate. The row width was 18", which was derived by splitting the rows with a 36" wide John Deere 7100 Max-Emerge, vacuum-type planter. Seeding rate was 225,000 seeds/acre.

The soil was a Grundy Silt Loam with 3.1% O.M, second bottom of the East Fork of Grand River field, located at the Hundley-Whaley Research Farm in Gentry County, Missouri. This soil type has a tendency to stay wet when covered with heavy residue and such was the case at the study site both springs. This was the case in 2001 despite the fact that the study site was moved to a better drained part of the farm.

The treatments consisted of both no-till and minimum tilled (spring-disked) plots. Planting was done with a 36" row planter set to deliver ½ of the desired seed needed for final planting rate. Following the initial pass across the plot, the tractor and planter then split the rows by placing and driving the tractor wheels on row 2 and 4 of the initial planting. Planting depth was 1-1 ½".

Disking with a tandem disk on April 9 & 10, prior to planting, accomplished the tillage in the tilled plots. This was the only time the plots were tilled. After the initial tillage, the conventionally tilled plots were planted into what could be called a "stale seedbed" with emerged weeds controlled by Roundup applications.

The study was planned for the first planting date to be in mid-March. After that, planting would be done at two-week intervals as long as the weather would allow. The very wet weather during the spring of 2001 made planting in March impossible. Planned & actual planting dates, and days deviation from planned dates, are shown in Table 1.

There were few weeds in the tilled or no-till plots at the beginning of the season. Weed control consisted of broadcast applications of Roundup at the rate of 1 quart/acre in a twenty gallon per acre spray solution as needed for weed control. These applications were made April 26, May 25, June 11 and July 1 in 2001, to all plots in the study. The primary weed species present at each spray application time were 3-5" tall giant foxtail and 1-6" common waterhemp.

Plant counts were taken on July 6, 2001, by selecting what looked like representative stands from three different locations in each plot and counting the live soybean plants in a three by three foot section of each plot.

The soybeans were mechanically harvested on October 26 with a Massey 35 plot combine. Harvest consisted of harvesting the four center rows of the eight row plots.

Results: The study was initiated on April 10 with the first soybean planting. Plantings were made at approximately two-week intervals following the first planting date. On July 6, plants were counted and a soybean stand was calculated. Unlike 2000, the year of 2001 did not result in damping of problems. The April 10 no-till planted plots did get planted, but we were rained out of the field before we could get the conventionally tilled plots planted. The results of this evaluation are found in Table 2.

The soybean harvest data is found in Tables 3 & 4 and Figures 1 & 2.

Figure 1

Figure 2

Discussion: For the second year, the soil in the plots was actually too wet to plant at the first planting date. In fact, the first planting in 2001 was delayed almost 1 month beyond the first planned planting date.

This year we did go out one more planting date than was originally planned in order to see what effect delayed planting dates had on crop performance.

There are several things that are hard to understand when looking at this year's data. Our best stands were obtained early in the planting season and our poorest stands were obtained with later planting dates. The only explanation for this might be a problem with seed quality in 2001. There was a lot of poor quality seed planted this spring and the seed lot we used might have been one of them. We do not have a way to test this hypothesis, however.

As last year, there was little statistical difference in soybean yields between the disked and no-till plots. Neither was there a major difference in soybean yields for the planting dates ranging from early to mid-spring. Soybean yields only started to drop when planting date was delayed past May 22. The highest soybean yield in both the disked and no-till plots was a result of the April 26 planting, and this yield was statistically higher than the June 11 planted soybeans. The April 10 planted no-till soybeans yielded less than the April 26 planted soybeans despite the poorer stand obtained with the later planting, but the difference in yield was not statistically significant.

There was no frost damage to any of the plantings.

Outreach: The study was explained in this year's Hundley-Whaley Field Day report. Over 800 copies of the report were distributed to people attending the field day. The data will be shared with northwest Missouri producers at three winter meetings. The data will also be shared with north Missouri producers through newsletters and newspaper articles this winter.

Future Plans: The study will be repeated in 2002 upon approval of funding support from the Missouri Soybean Merchandising Council.