Multi-Line Seeding for Corn and Soybeans – Year 4 (High Seeding Rate)

INTRODUCTION

This report very briefly reviews our fourth season of trials looking at variable-line seeding of corn and soybeans using a multi-hybrid planter. In the first season (2013) at the Tripp and Beresford sites we found on average a 5 bushel per acre yield gain with variable line planting in corn and a 3 bushel per acre yield gain in soybeans. In the second year of the study, we again found a 6 bushel yield advantage with corn with the right pairing of lines, but no advantage with corn or soybeans if the lines didn’t fit well. In the third year of the study we had above average rainfall in August and did not see a yield difference from multiline planting.

The basic logic behind this approach is that given our rainfall distribution (which peaks in May and June) versus the water requirements of corn and soybean crops (which peak in August) there is a good chance that in the same field in the same season the lowland parts of the field may be yield limited by excess moisture early in the season, while the upland positions on the landscape will be yield limited by drought stress in late July and August. It seems logical that gains in productivity within a field might be achieved by using lines with a more horizontal root profile and tolerance to wet conditions in lowland portions of the landscape, and switching to lines with a more vertical root profile and resistance to drought conditions in the upland portions of the landscape. The primary objective of this project is to make an initial evaluation of improvements in grain yield for corn and soybeans grown with a multi-line planting system versus planting a single line across the landscape.

METHODS

The project involved two soybean lines, each line selected for adaptation to either upland or lowland conditions. A variable rate seeding treatment was also included which involved a higher seed rate for soybeans the rates tested were the opposite with a reduced seed rate in the lower parts of the field (to avoid white mold) and a higher seed rate in the upper part of the field (Table 1). Plots were 30 feet wide for soybeans and ran the length of the field in each case (800 feet to 1700 feet). Soybean trials were planted on 7 June and 2 June 2016, at the research farm and at our cooperator’s field, respectively. Yield was measured directly using a weigh wagon to determine weight harvested from each plot. Data was analyzed using standard ANOVA with Proc GLM in SAS statistical software. There was a significant treatment by site interaction for yield in the soybean trials, so the two soybean sites were analyzed separately.

RESULTS

Previous work with mult-line planting with soybeans has also shown mixed results depending on line selection and weather during seed-filling. We saw a positive result in 2013 (3 bu/ac gain with multi-line seeding), no differences in 2014 (perhaps due to line selection), and no differences in 2015 (presumably due to above average rainfall in August of that year). In this year’s trials with soybeans, there was a significant benefit to multi-line seeding at the Southeast Research Farm, but not at our nearby cooperator’s field. The field at the Southeast Farm had more moisture at planting than did the cooperator’s field. This is consistent with the lower plant stand at the Southeast Farm site (about 15 % fewer plants at maturity). The two sites were planted with the same equipment and the same settings for seed rate. In the more difficult Southeast Farm site, multi-line seeding showed improved yield over P24T93R by itself (P < 0.10), and a trend for greater yield than P25T51R by itself (P < 0.25) (Table 2). P25T51R, which has more tolerance to wet conditions, outyielded P24T93R across the field at this site. However, multi-line seeding and including P24T93R in the upland positions showed a definite trend for greater yield (P 0.20) for all the treatments. This site had better planting conditions and was a tilled field and showed better stands although yields were similar at the end of the season.

SUMMARY

In summary, after four seasons of experiments with multi-line planting, we found significant (P < 0.10) yield benefits about half the time, and no yield loss in any case. For soybeans it was about 3 bu/ac. However, half the time we didn’t see a yield improvement with multi-line planting. While the logic behind multi-line planting is compelling, there are multiple parts to this equation to consider in order to capture the potential benefits that are there. First, on the planting side, one needs to be able to map the different management zones in the field and know where their boundaries are; second, one needs high-yielding lines that have strengths that match those particular zones; third, one needs equipment that accurately and precisely switches between lines on the go; fourth, the season and the weather need to fall within the range of your expectations.

If the weather is outside the range of your expectations or planning (for good or for ill) then your line selection won’t match conditions and you probably won’t see a yield advantage with multi-line planting. For example, in 2015 conditions during seed-filling were very good with well above average precipitation in July and August which came as well-dispersed rains – in this case everything did well and we didn’t see an advantage to multiline planting. On the other hand in 2014, we had record-setting precipitation in June, which completely flooded the better part of one of our research fields for more than a week – obviously nothing was going to perform well in those circumstances. Looking at this equation for successful multiline planting, the mapping and the equipment sides of this formula are pretty well worked out, and with good management they should not be a limitation. Looking at the weather, average temperature and rainfall for a given location can be calculated and is helpful, but as we all know the climate in any particular year is uncertain. For this reason, because one doesn’t know 100 % what the weather will do, all the lines selected should have good yield potential. It may be that your usual bad spot will turn out to be the best spot in the field if the weather is particularly suited for it (either wet or dry as the case may be).

Choose among high-yielding lines for the particular strengths you think a particular management zone will need. This is probably where the future of multi-line planting is at this point – with the seed companies and the plant breeders. If they can find it within their resources and business plans to develop high-yielding lines suited for particular stress environments and identify them for farmers, then there will be a large potential for this technology in the future. If not, then I think the benefits will still be there for matching lines to a given field environment, but the benefits will be more incremental and scattered.

Modified from:

https://www.sdstate.edu/sites/default/files/2016%20SERF%20AR%20FINAL.C.pdf

by Peter Sexton*, Douglas Prairie, and Barry Anderson

ACKNOWLEDGEMENTS

The authors would like to acknowledge the South Dakota Soybean Research and Promotion Council for supporting this project. The authors would also like to recognize Mr. Gordon Andersen and Mr. Matt Loewe for being willing to put trials on their operations and for their work in implementing these trials. The efforts of the crew at the SDSU Southeast Research Farm were critical for the successful completion of this project.