Project Details:

Soybean planting date and tillage interactions for variable rate seeding across management zones

Parent Project: Soybean planting date and tillage interactions for variable rate seeding across management zones
Checkoff Organization:Michigan Soybean Promotion Committee
Categories:Soil and tillage management, Crop management systems
Organization Project Code:18-27
Project Year:2018
Lead Principal Investigator:Missy Bauer (B&M Crop Consulting)
Co-Principal Investigators:

Contributing Organizations

Funding Institutions

Information and Results

Click a section heading to display its contents.

Project Summary

Many soybean planters being purchased by farmers today are equipped with the ability to vary the seeding rate as they go across the field. The idea of variable rate planting in soybeans may allow farmers to fine tune their plant populations based on management zones within a field. The foundation of the variable rate is that highly productive soils may produce adequate yields with lower plant populations and medium to poor productive soils may need higher plant populations to optimize yield. Previous studies with B&M Crop Consulting have shown an agronomic and economic improvement with variable rate soybean planting across management zones, but some environments seem to respond to higher average populations in the VRA prescription and others to lower average populations. Potential factors that may determine if the given VRA prescription should average a higher or lower population in a given field may be tillage, planting date, white mold history, and the bean type (in-line or bushy) being planted. Previous studies at B&M Crop Consulting have studied the bean type interaction with VRA prescriptions, although final conclusions are still being determined. Soybean planting date and tillage environment may affect emergence and early growth therefore VRA population ranges used across management zones may need to be fine-tuned. Further, soybean planting date and tillage may affect time to canopy closure. Since variable rate seeding embraces the variability in the fields this type of research should be done in normal sized fields, not small plot research.

Project Objectives

The objective is to determine if planting date and tillage environment should be taken into consideration when determining planting populations in variable rate planting. It will be determined if yields and economics of variable rate soybean planting can be improved by writing the prescriptions based on planting date and tillage. The effect of planting date, tillage, and population on the time to canopy closure will be evaluated. Further it will be determined whether yield components are affected differently based on planting date and tillage as populations change.

Project Deliverables

Progress of Work

Updated October 8, 2019:
Field trials were conducted in two locations in south central Michigan. This was the second year of a two year study (2017 & 2018). Soybean treatments included two planting dates, two tillage systems, and two variable rate application (VRA) population prescriptions. The planting dates targeted were early planting (weather dependent late April or early May) and late planting (weather dependent after May 15th). The tillage systems were no-till and vertical tillage. A Great Plains Turbo-Max vertical tillage tool was used for the vertical tillage treatments. VRA A prescription had a higher average population across the field and VRA B prescription had a lower average population across the field. The approach for the VRA treatments was based on the idea of increasing populations in poorer management zones and decreasing populations in highly productive zones. The experiments were established with a split plot randomized complete block design, with eight treatments, and three replications. The tillage was in blocks split by the VRA prescription. The plots were field size; length of field by 38.75 to 77.5 foot wide. The exact size of the individual plots was determined by the field and equipment size. The planter was a Case-IH 2140 Early Riser with electric vDrive; 38.75-ft wide with 31-15” rows. The seeding rates below were actual planter settings.

Final Project Results

Updated October 14, 2019:

The early planting date increased yields on average 3.1 to 4.8 bu/ac. The earlier planting dates resulted in reaching 75% emergence 10 to 19 days sooner than the late planting date. The V1 growth stage was reached 7 to 16 days sooner than the late planting. The sooner V1 is reached the more opportunity for a higher total number of nodes on a plant. The early planting dates increased canopy closure 4.6 to 15 days sooner than the late planting dates. An earlier calendar date of canopy closure will improve total light capture and potentially lead to increased yields. The number of pods and seeds per plant was increased in 3 out of the 4 site locations with the early planting date compared to late planting. The increase in pods came from an increase in nodes per plant or an increase in the number of pods per node depending on the location. In the one site year location where pods and seeds per plant were not increased with early planting date, final populations were a driving factor instead.

Vertical tillage increased yields in both the early and late planting date averaging 2.0 bu/ac across the site year locations. The early planting date averaged 4.1 bu/ac increase across the locations in 2017 and 2018. The overall objective was to determine if the VRA prescription should be changed based on planting date and tillage. The best economical treatment across the site year locations was early planting with vertical tillage and the lower average population (VRA B). In comparing early planting vertical tillage with VRA B to planting late in no-till with VRA B; yields increased an average of 6.7 bu/ac across the site year locations. If planting late, vertical tillage and higher populations were important and increased yields an average of 3.2 bu/ac compared to no-till with lower populations. Population should be adjusted based on planting date by increasing population with later dates. Tillage was not consistently influenced by population. However, in the late planting dates, the no-till treatments did have higher yields with VRA A prescription but it was not always economical. Although in 2017, which was a cooler early growing season, it was economical to have the higher prescription in no-till with the late planting date.

Benefit to Soybean Farmers

Many farmers may soon have the technology for VRA soybean planting. The previous studies conducted by B&M Crop Consulting (2013 & 2014) showed an agronomic and economic value of implementing variable rate. However, little information is available if the planting date and/or tillage system should be taken into consideration when writing variable rate prescriptions. This study may help soybean farmers to improve profitability by fine tuning their seeding rates by planting date and tillage system across management zones. This could also help farmers without variable rate determine if planting date and tillage should be taken into consideration when determining the average planting population on a field by field base. In addition to the Michigan Soybean Promotion Committee publishing the data results from this would be shared with Michigan soybean growers through B&M Crop Consulting meetings, Farm Journal Magazine, and other various speaking events.

Performance Metrics

Project Years