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There were no 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 25, May 19 and June 12 to all plots in the study. The primary weed specie present at each spray application time was 3-5" tall giant foxtail. Plant counts were taken on June 14 by selecting what looked like representative stands from three different locations in each row and counting the live soybean plants in a three foot section of each row. The soybeans were mechanically harvested on October 9 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 March 28 with the first soybean planting. Plantings were made at approximately two-week intervals following the first planting date. On May 17, a subjective evaluation was made estimating the percent emergence and percent of seedling dampened off for the two most vulnerable and earliest planting date soybeans. The results of this evaluation are found in Table 2.
The results of the plant counts taken on June 14 is found in Table 3. The stand in the early planted soybeans, for both the no-till and disked plots were significantly less than the later planting dates. The poorest stand was obtained in the no-till, March 28 planted soybeans.
The soybeans harvest data is found in Table 4 and Figure 1.
Summary: The soil in the no-till plots was actually too wet to plant at all planting dates, despite the very dry spring. This was due to the very heavy giant foxtail residue and the poor internal drainage of this particular soil type. The very early planted no-till plots did delay soybean emergence by 7-10 days. The late March no-till planted soybeans suffered from considerable dampening-off compared to the conventionally tilled soybeans. While the treated seed might have provided some protection from dampening-off organisms, it was not enough. There was no statistical difference in soybean yields in the disked plots for the planting dates ranging from March 28 through May 12. The highest soybean yield in both the disked and no-till plots was a result of the April 12 planting and this yield was statistically higher than the May 30 planted soybeans. The very early planted no-till soybeans yielded significantly less than the very early soybeans in the disked plots. With the exception of the March 28 planting date, there was no difference in soybean yields between the soybeans in the disked treatments and soybeans in the no-till treatments. If the practice of very early, no-till soybean planting is to successful, it will likely need to be made on well-drained soils that dry out sooner than the soils in these plots. The last killing frost occurred on April 12 this year. None of the planted beans had emerged by that time. Consequently there was no frost damage. A late April or early May killing frost could have resulted in a different outcome for the trial. 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 2001, with the approval of funding support from the Missouri Soybean Merchandising Council. However, the study site for 2001 will be moved to a better-drained area of the farm.
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