Planting date is one of the most crucial aspects of crop production. The ability to get a crop in the ground in a timely manner can be the difference between making a profit or a loss. As shown in Figure 1, the optimal planting date for soybeans grown in Mississippi would be around April 20^{th} (Julian Day 110). Every day before April 20^{th} reduces yield by 0.51bu/ac, and for every day after, yield decreases by 0.39bu/ac. The goal should be to plant as many acres around this date as possible. One way to do that is by increasing planting speed. To illustrate the impact that planting speed can have on yield, costs, and net returns we can compare a traditional mechanical planter planting at 5 mph to a precision planter planting at 9 mph.

First, for simplicity’s sake, we will assume a 2,000-acre soybean farm. Using the standard machine cost calculation formulas, a 12-row 38-in row-spacing mechanical planter is going to plant 15 acres per hour (planting at 5 mph), and the same size precision planter is going to plant 26.9 acres per hour (planting at 9 mph). This means a mechanical planter would take 133.6 hours to plant 2,000 acres and a precision planter would only take 74.2 hours. We could just use those numbers to determine when to start planting but that doesn’t consider the fact that weather can prevent farmers from actually getting in the field. The USDA NASS collects data on how many days in a given week are suitable for fieldwork. For this example, we use the average days suitable for fieldwork from 2019-2023 in Mississippi. Table 1 shows the yield, planter speed, and days suitable for fieldwork by week.

One drawback to the precision planter is that it is going to cost more to purchase. A mechanical planter costs around $106,000, and the same size precision planter will be about $150,000. However, because of increased planting speed which results in fuel efficiency and labor savings, the operating cost per acre is actually less for the precision planter at $15.81/acre compared to $19.20/ac for the mechanical planter. For more information on machine cost calculations, see: http://extension.msstate.edu/publications/farm-machinery-cost-calculations

Putting all this together and some back-of-the-napkin math, the optimal start date for the mechanical planter would be April 9^{th} (Julian 99) and April 14^{th} (Julian 104) for the precision planter (Table 2). A precision planter would reduce the days of planting from start to finish from 23 days to 13 days and thus increase yield by 1.2 bu/ac. Assuming a soybean price of $12.00/bu, this would increase revenue by $14.07/ac. Costs would be decreased by $3.38/ac leading to an increase in net returns of $17.45/ac. Effectively, the additional cost of the precision planter would pay for itself in 2 years for a 2,000-acre farm.

Now, this analysis is pretty basic and makes some broad assumptions. It is important to look at your state’s planting date yield data to determine when is optimal for you to plant. Larger farms are going to benefit from higher planting speeds more than smaller farms. It also assumes that there is no yield loss when planting faster. Preliminary data at Mississippi State shows there isn’t a yield hit, but this could vary depending on your situation. Nevertheless, the basic idea is that by planting faster a producer could capture higher yields. So be a maverick and bump that cruise speed up.

**Figure 1. Effect of Planting Date on Soybean Yield in Mississippi from Batemen et al. (2020)**

Table 1. Weekly comparison between mechanical and precision planter for Mississippi | |||||

Period | Average of Soybean Yield bu/ac | Days Suitable for Fieldwork 2019-2023 | Hours per Day Suitable for Farming^{a} | Mechanical Planter Acres Per Day | Precision Planter Acres Per Day |

Week 12 | 59.1 | 2.9 | 4.9 | 74.1 | 132.8 |

Week 13 | 62.6 | 3.4 | 5.8 | 86.9 | 155.9 |

Week 14 | 66.2 | 3.1 | 5.4 | 80.7 | 144.8 |

Week 15 | 69.8 | 2.8 | 4.8 | 71.5 | 128.2 |

Week 16 | 71.5 | 3.5 | 6.1 | 91.0 | 163.2 |

Week 17 | 68.7 | 3.9 | 6.7 | 100.8 | 180.8 |

Week 18 | 65.9 | 4.6 | 7.8 | 117.3 | 210.3 |

Week 19 | 63.2 | 4.0 | 6.8 | 101.8 | 182.6 |

Week 20 | 60.5 | 5.4 | 9.2 | 137.8 | 247.2 |

Week 21 | 57.7 | 5.7 | 9.7 | 145.5 | 261.0 |

Week 22 | 55.0 | 5.6 | 9.5 | 143.0 | 256.4 |

References

Bateman, N.R., Catchot, A.L., Gore, J., Cook, D.R., Musser, F.R., & Irby, J.T. (2020). Effects of Planting Date for Soybean Growth, Development, and Yield in the Southern USA. *Agronomy.* https://doi.org/10.3390/agronomy10040596

Johnson, J., & Mills, B.E. (2023). Farm Machinery Cost Calculations. Mississippi State University Extension P3543. Available at: http://extension.msstate.edu/publications/farm-machinery-cost-calculations

USDA NASS. (2024). Days Suitable for Fieldwork. Available at: https://quickstats.nass.usda.gov/

Mills, Brian, Mike Mulvaney, Wes Lowe, and Oluwaseyi Olomitutu. “Planting Date: The Need for Speed.“* Southern Ag Today* 4(12.3). March 20, 2024. Permalink